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A simple, sustainable, one-pot, and highly efficient protocol for the synthesis of 5-hydroxymethyl furfural (5-HMF) and furfural from waste papers, cotton, poly/mono-meric carbohydrates using a hydrothermal reactor system has been demonstrated. The synergetic role of oxalic acid and LiCl was investigated for the conversion of different types of waste paper such as cardboard, newspaper, tissue paper, white paper, and cotton in a greener solvent media THF-water to 5-HMF and furfural production. Moreover, the influence of reaction time, temperature, oxalic acid and LiCl concentrations, and the impact of different solvents were critically examined to procure 27–79 and 39–62 mol% yields of 5-HMF and furfural respectively. This study also elucidates the relative compositions of various waste paper/cotton, and the quantification of desired products were determined through the ultra-performance liquid chromatography (UPLC) analysis technique with 85–95% products purity. [Display omitted] • Utilization of untreated waste papers, cotton and poly/monomeric carbohydrates. • Waste papers are viable biomass feedstock for 5-HMF and furfural production. • Optimized protocol provides 27–79 and 39–62 mol% yields of 5-HMF and furfural. • Plausible reaction mechanism for direct conversion of biomass was proposed. [ABSTRACT FROM AUTHOR]

The contamination of paper products by various chemicals has been reported on a global level, but to date, no published research has investigated pharmaceutical contamination of paper-based products. In this study, pharmaceutical analysis was conducted on 42 samples collected from various points of the recycled paper value chain in Cape Town, South Africa, which included the various grades that may be included in the manufacturing of recycled paperboard. The analysis was achieved by ultrasonic-assisted extraction of paper samples before detection by UHPLC-Q Orbitrap. Quantification limits ranged from 1.15 pg/g for ketoprofen to 46.07 pg/g for methocarbamol. Pharmaceuticals identified in newspaper samples were dexamethasone, ketoprofen, and 17β-estradiol. The latter was also detected in paper shopping bags (up to 697.49 ng/g), infant bathtub packaging (280.62 ng/g), battery packaging (137.43 ng/g), and an egg carton (170.47 ng/g). Carbamazepine was also prominent with its concentration reaching 13.02 ng/g in a vegetable box. Suspect screening tentatively identified 14 additional pharmaceuticals in paper samples, with minocycline, prazepam, and anabolic steroids appearing more prominently. This pioneering study indicated that unintentional pharmaceutical exposure had expanded beyond environmental media to consumer products. [Display omitted] • The first reported occurrence of pharmaceuticals contamination in paper samples. • Targeted and suspect screening of various paper grades was performed. • Sensitive analytical method developed using UHPLC- Q Orbitrap. • Reveals the propagation of emerging contaminants beyond environmental matrices. • Consumer usage and waste management protocols contributed to pharmaceutical occurrence. [ABSTRACT FROM AUTHOR]

Highlights • Developers were identified in 311 receipts and other thermal paper products. • BPA was the most frequently detected main developer. • Detection of BPA showed a statistically significant difference between continents. • In 1/3 of the European samples, an alternative developer was detected. • BPS and Pergafast 201 were most used alternative developers. Abstract Thermal printing is a fast, widespread and inexpensive technology that uses a developer to produce a print on the paper, among many applications. A common developer is bisphenol A (BPA), used for this purpose in its free form. Consequently, the handling of thermal paper, as evaluated by the European Food Safety Authority, was reported to be the second largest source of external human exposure to this endocrine disrupting chemical. Recently, reports have been made on the substitution of BPA by alternative developers, which are yet less studied. In this study, 311 receipts and other thermal paper products were collected from 14 countries in Europe, Asia, North America and Oceania and analysed using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. BPA was the most frequently used main developer and was detected in 194 thermal paper samples, which represents a detection frequency of 63%. A statistically significant difference in the detection of BPA was shown between continents. BPA was followed by bisphenol S (BPS) which was detected in 64 samples as the main developer. Pergafast 201 was the third most abundant main developer and detected in 37 samples as the main developer. Less frequently used main developers included BPS-MAE, TGSA, d -8, and d -90, many of them being BPS derivatives. Two oligomers of d -90 (n = 1 and n = 2) were also identified. The sensitizer diphenyl sulphone (DPS) was identified using high-resolution mass spectrometry for the first time and detected in combination with other developers than BPS for the first time. Despite the lack of structural, nation-wide legislation prohibiting the use of BPA in thermal paper, it is clear that alternative developers are currently globally in use for the manufacturing of thermal paper. [ABSTRACT FROM AUTHOR]

• Brief presentation of the metabolism of vitamin D. • Detailed presentation of preanalytical variables affecting the measurement of vitamin D metabolites. • Detailed presentation and recommendations on the analytical measurement and clinical usefulness of vitamin D metabolites. • Current status and future goals for the standardization of analytical methods. Vitamin D, an important hormone with a central role in calcium and phosphate homeostasis, is required for bone and muscle development as well as preservation of musculoskeletal function. The most abundant vitamin D metabolite is 25-hydroxyvitamin D [25(OH)D], which is currently considered the best marker to evaluate overall vitamin D status. 25(OH)D is therefore the most commonly measured metabolite in clinical practice. However, several other metabolites, although not broadly measured, are useful in certain clinical situations. Vitamin D and all its metabolites are circulating in blood bound to vitamin D binding protein, (VDBP). This highly polymorphic protein is not only the major transport protein which, along with albumin, binds over 99% of the circulating vitamin D metabolites, but also participates in the transport of the 25(OH)D into the cell via a megalin/cubilin complex. The accurate measurement of 25(OH)D has proved a difficult task. Although a reference method and standardization program are available for 25(OH)D, the other vitamin D metabolites still lack this. Interpretation of results, creation of clinical supplementation, and generation of therapeutic guidelines require not only accurate measurements of vitamin D metabolites, but also the accurate measurements of several other "molecules" related with bone metabolism. IFCC understood this priority and a committee has been established with the task to support and continue the standardization processes of vitamin D metabolites along with other bone-related biomarkers. In this review, we present the position of this IFCC Committee on Bone Metabolism on the latest developments concerning the measurement and standardization of vitamin D metabolites and its binding protein, as well as clinical indications for their measurement and interpretation of the results. [ABSTRACT FROM AUTHOR]

Abstract N-benzylphenethylamines derivatives, such as NBOMe and NBOH series, are potent hallucinogen drugs that are usually sold in the illicit market as blotter papers containing "legal" LSD alternatives. The identification of these drugs is mainly performed by liquid or gas chromatography coupled with mass spectrometry, but there is a lack of a rapid screening methods to identify samples containing or not drugs of these series. For this purpose, this work offers a fast and non-destructive method applying a handheld NIR spectrometer for discrimination of drugs absorbed in blotter papers using PLS-DA and SIMCA. The method was developed in a two-stage approach: Model A for identification of samples containing or not drugs and model B for identification of samples containing NBOMe or NBOH drugs. PLS-DA models have provided efficiency rates higher 97% in both training and validation phases. Robustness of model B was evaluated with a random permutation of samples among training and validation phases, given mean efficiency rates higher than 89%. SIMCA models presented equivalent efficiency for model A, but lower efficiency for model B comparing to PLS-DA results. However, SIMCA showed a higher efficiency to deal with samples containing drugs not included in the training phase. Results support use of this method for in loco forensic analysis and as a screening method prior the chromatographic and mass spectrometry analysis. Graphical abstract Unlabelled Image Highlights • In loco analysis of NPS in blotter papers • Analysis of NPS recently described in the literature • Fast screening method for forensic analysis • Two stage model for NPS presence and their identification [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Application of an ambient MS method, paper spray MS, for sensitive and accurate analysis of antibiotic residues in foodstuff. • Multiplexed analysis of antibiotics with qualitative and quantitative capabilities. • High sensitivity/specificity, no need of analyte labelling, and readiness to couple with a miniature mass spectrometer. Abstract Antibiotics monitoring is of importance in providing healthy diets by preventing animal husbandry from antibiotic misuse. The development of paper spray provides a time-efficient strategy to analyze antibiotics in complex matrices without sample preparation. In this work, paper spray mass spectrometry was applied to identify and quantify nine antimicrobial residues in four antimicrobial families from four kinds of general food matrix, including beef, chicken meat, milk and egg. Samples were directly placed on the paper without any further sample treatment. The limits of detections (LODs) were obtained as 15.0 μg/kg for marbofloxacin in chicken meat, 15.0 μg/kg for difloxacin in chicken meat, 12.5 μg/kg for lincomycin in beef, 12.5 μg/kg for clindamycin in beef, 4.0 μg/kg for amoxicillin in milk, 4.0 μg/kg for penicillin-G in milk, 10.0 μg/kg for cloxacillin in milk, 12.5 μg/kg for minocycline in egg, and 6.2 μg/kg chlortetracycline in egg, respectively. All the LODs were in accordance with the restriction of maximum residue limits (MRLs) of antimicrobial residues announced by the Council Regulation 2377/90/EEC, which suggests a sufficient capability of the paper spray mass spectrometry (PS-MS) method to rapidly screen antimicrobial residues in foods of animal origins. [ABSTRACT FROM AUTHOR]

Background Fentanyl is a potent, synthetic opioid at the centre of an international health crisis that has seen thousands of fatal overdoses. Most analytical methods focus on the detection of fentanyl in blood and/or urine ( i.e. , post-drug use). Harm reduction (including pre-screening before drug use) may be an effective strategy against fentanyl overdoses. Method Paper spray-mass spectrometry (PS-MS) is an inexpensive, direct sampling strategy where a small volume of sample (<10 μL) is spotted onto a piece of paper that is then wetted and connected to high voltage. Ions are emitted from the paper and enter a mass spectrometer for sensitive and selective semi-quantitation using labeled internal standards. Results We present the use of PS-MS for the direct measurement of fentanyl and norfentanyl using a custom PS interface, demonstrating that paper tip position and quality can significantly affect quantitative results. Furthermore, we observe comparable calibrations for fentanyl and norfentanyl (0.5 to 600 ng/mL) across a variety of complex matrices (methanol, diluted urine, analgesic slurry). Detection limits for fentanyl are as low as 0.049 ng/mL (0.4 pg total material) in methanol, and 0.66 ng/mL (5.3 pg total material) spiked in an analgesic slurry (illicit substance simulation). PS-MS was compared with liquid chromatography-MS for the analyses of real urine samples, with satisfactory results. Conclusion PS-MS shows potential as a sensitive and selective direct measurement strategy for use in fentanyl harm reduction strategies, and may also be used for pre-screening in advance of or in combination with more conventional ( i.e. , chromatographic) analyses. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA), a synthetic xenoestrogen widely used in various industrial fields, can be present, in its un-reacted form, as an additive in thermal paper. BPA is virtually ubiquitous in industrialized societies and humans are exposed to this chemical via dietary and non-dietary sources. Since in 2015 European Food Safety Authority (EFSA) indicated that thermal paper is the second source of BPA exposure after the food chain, some suppliers replaced BPA with its analogue Bisphenol S (BPS), speculatively supposed to be safer. In this work BPA and BPS concentration levels were determined in thermal paper receipts collected in Italy from 50 different sources by liquid chromatography coupled to tandem fluorescence and ultraviolet detection. BPA was found in 44 samples at mean concentration of 107.47 μg/100 mg of paper (from below Limits of Quantification (LOQ) to 1533.733 μg/100 mg of paper). BPS was found in 31 samples at mean concentration of 41.97 μg/100 mg of paper (from below the LOQ to 357.989 μg/100 mg of paper). 26 samples were positive to both BPA and BPS. The estimate daily intake (EDI) values of BPA and BPS occurring through dermal absorption were calculated for 70 kg body weight individuals. For general population, they were 0.0625 μg/day for BPA and 0.0244 μg/day for BPS, based on the mean content of bisphenols found. For occupationally exposed individuals, they were 66.8 μg/day for BPA and 15.6 μg/day for BPS, based on the worst scenario. Such levels would produce a dermal intake below the Tolerable Day Intake established by EFSA (4 μg/kg·bw/day); nevertheless, the occurrence of co-exposure to dietary and non-dietary sources should be considered in the health risk assessment, mainly for people frequently exposed to thermal paper contact for occupational reason. [ABSTRACT FROM AUTHOR]

Abstract: Recycling paper mill effluent by conventional water treatment is difficult due to the persistence of salt and recalcitrant organics. Elimination of dissolved organic matter (DOM) from paper mill effluent was studied using three treatment options, ion exchange resin (IER), granular activated carbon (GAC) and nanofiltration (NF). The removal efficiency was analysed based on hydrophobicity, molecular weight and fluorogenic origin of the DOM fractions. For IER, GAC and NF treatments, overall removal of dissolved organic carbon was 72%, 76% and 91%, respectively. Based on the hydrophobicity, all the three treatment methods majorly removed hydrophobic acid fractions (HPhoA). Further, IER acted on all fractions, 57% of HPhoA, 44% of transphilic acid and 18% of hydrophilics, substantiating that the removal is by both ion exchange and adsorption. Based on the molecular weight, IER and GAC treatments acted majorly on the high molecular weight fractions, whereas NF eliminated all molecular weight fractions. After GAC adsorption, some amount of humic hydrolysates and low molecular weight neutrals persisted in the effluent. After IER treatment, amount of low molecular weight compounds increased due to resin leaching. Qualitative analysis of fluorescence excitation emission matrices showed that the fulvic acid-like fluorophores were more recalcitrant among the various DOM fractions, considerable amount persisted after all the three treatment methods. Three treatment methods considerably differed in terms of removing different DOM fractions; however, a broad-spectrum process like NF would be needed to achieve the maximum elimination. [Copyright &y& Elsevier]

• We applied liquid chromatography-tandem mass spectrometry to the analysis of historical iron gall ink recipes. • We characterised ageing markers of iron gall inks by HPLC-ESI-Q-ToF. • We highlighted different degradation trends depending on historical recipes and ageing conditions. • We proved that it is possible to use 15 µg as minimum amount of sample for the HPLC-ESI-Q-ToF analysis of iron gall inks. Several manuscripts and drawings of our historical and artistic heritage have been produced with iron gall inks. To obtain an iron gall ink, ancient treatises cite the addition of ferrous sulphate and gum Arabic to a decoction of oak galls as a basic procedure. Owing to the development of synthetic chemistry, iron gall ink recipes were improved with new materials and procedures in the late 19th and early 20th century. Notably, many conservation issues arise from the interaction between iron gall inks and the paper support of manuscripts and drawings. To date, most of the research on the topic are focused on paper preservation by non-destructive analytical methods, which provide only limited information on degradation process trends and minor components, representative of iron gall ink's recipes. In the present work, three historical recipes of iron gall inks (alizarine ink, Reid ink, modern gall ink) , dated to 19th-20th century and differing for the preparation method and additives, were characterized. The molecular markers of iron gall inks and of gallic acid degradation were detected by an optimized protocol based on high performance liquid chromatography coupled to high resolution mass spectrometry (HPLC HRMS). Furthermore, by performing ageing tests on reference materials in different indoor conditions (natural light and stored in the dark), two degradation mechanisms were observed: hydrolysis of poly-galloyl glucose species and auto-oxidation of gallic acid. Thus, different chemical profiles and ageing trends were revealed depending on the starting recipe. The procedure Limit of Detection (LOD) was estimated, improving the approaches reported so far in the literature. Finally, the strategy was successfully applied for the characterisation of the ink employed in a very degraded 16th century manuscript, granting access to the complete molecular profile of an iron gall ink with just 15 µg of sample. [Display omitted] [ABSTRACT FROM AUTHOR]

• A microfluidic PMMA/paper detection (MPD) system for cyclamate concentration in foods. • The system comprises a MPD microchip and a microanalysis box. • Cyclamate concentrations of 10 commercial food samples are measured. • The measurement results deviate by no more than 4.8% versus official LC-MS/MS method. Cyclamate is an artificial sweetener with high sweetness and low calories, and is a common sugar substitute for weight control and diabetic patients. However, excessive cyclamate consumption is associated with various health disorders, and hence it is prohibited as a food additive in many countries around the world. The current research proposes a light-shading reaction microfluidic PMMA/paper detection (MPD) system for determining the cyclamate concentration in food. In the current system, inject 10 μL of the extracted sodium cyclamate sample into the sample chamber of the MPD device, perform the diazotization reaction under shading conditions, and then suck it into the detection area through a paper strip, which consists of a paper chip embedded with modified Bratton-Marshall reagent. Once the paper chip is thoroughly wetted, the MPD device is inserted into a microanalysis box, where a fuchsia azo reaction compound is produced through heating at 40 °C for 3 min. The reaction complex is observed by a camera and the reaction image is wirelessly transmitted to a smartphone, and the concentration of sodium cyclamate is measured through the self-developed grayscale software. The results obtained for the sodium cyclamate samples with a concentration in the range of 50–1000 ppm show that the measured gray value changes linearly with the sodium cyclamate concentration, and the correlation coefficient (R2) is 0.9898. By analyzing the concentration of sodium cyclamate in 10 real-world samples, the practical feasibility of the current MPD system is proved. The results showed that the concentration measurement value did not deviate by more than 4.8 % from the value obtained using the conventional liquid chromatography/tandem mass spectrometry (LC-MS/MS) method. [ABSTRACT FROM AUTHOR]

Abstract: A cost-effective HPLC method for determination of pyrimethamine (PYR) in human whole blood samples dried on filter paper (Whatman®) is reported. Trimethoprim (TMP) was used as an internal standard. Whole blood spiked with PYR was transferred (100μl) onto filter paper and dried at room temperature. Capillary blood samples (100μl) after ingestion of three tablets of sulfadoxine-pyrimethamine (SP) by one subject were also tested. PYR and an internal standard (IS) TMP were extracted into di-isopropyl ether as bases and then re-extracted with 150μl mobile phase. A C-18 column was used and the mobile phase consisted of phosphate buffer (0.05M, pH 5):acetonitrile:concentrated perchloric acid (750:300:2.5, v/v/v). The absorbances of PYR and IS were monitored at 270nm. The limit of quantification was 40ng/ml. The within- and between-assay coefficient of variations were <10% at the limit of quantification. [Copyright &y& Elsevier]

Abstract: A bioanalytical method for the determination of lumefantrine in 100μl blood applied onto sampling paper, by solid-phase extraction and liquid chromatography, has been developed and validated. Whatman 31 ET Chr sampling paper was pre-treated with 0.75M tartaric acid before sampling capillary blood to enable a high recovery of lumefantrine. Lumefantrine was extracted from the sampling paper, then further purified using solid-phase extraction and finally quantified with HPLC. The between-day variation was below 10% over the range 0.4–25μM. The lower limit of quantification was 0.25μM in 100μl capillary blood. No decrease in lumefantrine concentration in dried blood spot is seen after 4 months storage at 22°C. The method was also evaluated in field samples from patients in Tanzania after treatment with lumefantrine/artemether. Lumefantrine could be estimated accurately enough to assess bioavailability and treatment compliance on day 7 (i.e. 4 days after the last dose) after a standard regimen with the lumefantrine/artemether combination. [Copyright &y& Elsevier]

Abstract: Packaging can represent a primary source of food contamination with mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH), especially when recycled cardboard or mineral oil based printing inks are used. A pressurized liquid extraction (PLE) method, followed by on-line LC–GC analysis, has been optimized for rapid mineral oil determination in cardboard and paper samples. The proposed method involves extraction with hexane (2 cycles) at 60°C for 5min, and allows for the processing of up to 6 samples in parallel with minimal sample manipulation and solvent consumption. It gave good repeatability (coefficient of variation lower than 5%) and practically quantitative extraction yield (less than 2% of the total contamination found in a third separate cycle). The method was applied to different cardboards and paper materials intended for food contact. Results obtained were similar to those obtained by applying classical solvent extraction with hexane/ethanol 1:1 (v/v) as described by Lorenzini et al. [20]. [Copyright &y& Elsevier]

A comparative study of the performance of liquid chromatography (LC)–atmospheric pressure chemical ionisation (APCI)–mass spectrometry (MS) and gas chromatography (GC)–mass spectrometry techniques for the determination of resin and fatty acids from paper mill process waters was carried out. These compounds are responsible for the high toxicity of paper mill effluents and little research has been carried out regarding their analysis using mass spectrometric techniques. To prove the usability of GC and LC–MS, 16 treated and untreated water samples of recycle, kraft and pulp paper mills were analysed and good agreement was observed as regards to compounds detected and corresponding concentrations. This paper also reports the limits of detection, recoveries, reproducibility, linearity and precision using the two methods. GC–MS presented better selectivity and lower detection limits (below 0.2 μg/l), but derivatization of the extracts and the short life of derivatives (12–24 h) made the technique tedious and prone to high variations. Although LC–APCI–MS presented coelution of the non-aromatic resin acids, it also showed good sensitivity (limits of detection <3 μg/l) and permitted the detection of resin and fatty acids at μg/l level. In addition, since samples could be directly injected to the chromatographic system, LC–APCI–MS was proven as a powerful technique for quick and unequivocal quality control during papermaking. [Copyright &y& Elsevier]

Per- and polyfluoroalkyl substances (PFAS) are a group of chemicals that have been widely used by various industries, including the food contact material industry. These substances are favoured for their ability to repel oil and resist moisture. However, exposure to PFAS has been linked to several health problems, including effects on the immune system. According to the European Food Safety Authority (EFSA), food contact materials (FCM) are likely to contribute to human exposure to PFAS. Therefore, this study investigated the exposure to PFAS from FCM. One hundred and ten FCM made of paper and board (e.g. straws, cups, bowls, boxes etc.), sugar cane or wheat pulp-based FCM, called paper analogues (e.g., cup, bowls, plates, hamburger boxes etc.) were carefully selected on the Belgian market and investigated using liquid chromatography coupled with high-resolution mass spectrometery. Out of the 25 PFAS targeted, 11 were detected in the samples, mainly perfluoroalkyl carboxylic acids (PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA) and PFOS. It was found that all of the paper analogue samples contained PFAS, while 43% of the paper and board samples showed the presence of these chemicals. Except for one sample, most detections suggest contamination rather than intentional use. Finally, a risk assessment was conducted, which revealed potential risks for consumers related to a coffee cup made of paper and board and a food tray made of sugar cane. [Display omitted] • Food contact materials (FCM) contributes to human exposure to PFAS substances. • Paper analogues FCM are more contaminated up to a factor 10 compared to paper and board FCM. • Risk assessment highlighted risks for the consumers regarding a coffee cup and a food tray. [ABSTRACT FROM AUTHOR]

Abstract: The determination of perfluorooctanoate (PFO) in articles of commerce has become increasingly important to understand if treated products are a possible source of PFO. An LC–MS/MS method for the determination of PFO in paper and textile using a dual labeled 13C-PFOA internal standard was successfully developed and validated. Residues of PFO were determined using an isocratic, reversed-phase high-performance liquid chromatography (HPLC) method with an ammonium acetate/methanol buffer. Ions monitored were 413 (parent) and 369 (daughter) for PFO and 415 (parent) and 370 (daughter) for dual labeled 13C-PFOA internal standard. As a precaution against ubiquitous PFO that occasionally occurs in mobile phase or instrument components, two Hypercarb™ cartridges (4mm) were placed before the HPLC injector. Any PFO that was captured by the cartridges was removed before each injection by flushing the system with 100% methanol prior to equilibration with the isocratic mobile phase. Overall recovery and standard deviation over a 3 day validation regimen for samples (n =54–55) fortified with PFOA at 5, 50, and 200ngg−1 were 114±4.9% for textile and 110±7.6% for paper. The results also established a limit of detection (LOD) of 1ngg−1 in textile and 2ngg−1 in paper based upon S/N of the 5.0ngg−1 fortification versus the untreated paper and textile. [Copyright &y& Elsevier]

Abstract: In this study, the efficiency of six ion exchange resins to reduce the dissolved organic matter (DOM) from a biologically treated newsprint mill effluent was evaluated and the dominant removal mechanism of residual organics was established using advanced organic characterisations techniques. Among the resins screened, TAN1 possessed favourable Freundlich parameters, high resin capacity and solute affinity, closely followed by Marathon MSA and Marathon WBA. The removal efficiency of colour and lignin residuals was generally good for the anion exchange resins, greater than 50% and 75% respectively. In terms of the DOM fractions removal measured through liquid chromatography–organic carbon and nitrogen detector (LC–OCND), the resins mainly targeted the removal of humic and fulvic acids of molecular weight ranging between 500 and 1000gmol−1, the portion expected to contribute the most to the aromaticity of the effluent. For the anion exchange resins, physical adsorption operated along with ion exchange mechanism assisting to remove neutral and transphilic acid fractions of DOM. The column studies confirmed TAN1 being the best of those screened, exhibited the longest mass transfer zone and maximum treatable volume of effluent. The treatable effluent volume with 50% reduction in dissolved organic carbon (DOC) was 4.8 L for TAN1 followed by Marathon MSA – 3.6L, Marathon 11 – 2.0L, 21K-XLT – 1.5L and Marathon WBA – 1.2L. The cation exchange resin G26 was not effective in DOM removal as the maximum DOC removal obtained was only 27%. The resin capacity could not be completely restored for any of the resins; however, a maximum restoration up to 74% and 93% was achieved for TAN1 and Marathon WBA resins. While this feasibility study indicates the potential option of using ion exchange resins for the reclamation of paper mill effluent, the need for improving the regeneration protocols to restore the resin efficiency is also identified. Similarly, care should be taken while employing LC–OCND for characterising resin-treated effluents, as the resin degradation is expected to contribute some organic carbon moieties misleading the actual performance of resin. [Copyright &y& Elsevier]

Abstract: A simple, sensitive, selective and reproducible method based on liquid chromatography was developed for the determination of chloroquine (CQ) and its active plasma metabolite desethylchloroquine (DECQ) in finger-pricked capillary blood spot onto filter paper (DBS) and whole blood samples. Both were separated from the internal standard quinine on a reversed phase C18 column, with the mobile phase consisting of a mixture of 1% diethylamine, acetonitrile and methanol (20:55:25, v:v:v) running at a flow rate of 1.0ml/min. Retention times of QN, DECQ and CQ were 4.5, 5.7 and 6.4min, respectively. Ultraviolet detection was at the wavelength 256nm. Sample preparation was done by extraction with hexane and tert-butyl methyl ether (1:1, v:v). Good precision and accuracy were obtained for both within-day repeatability and day-to-day reproducibility. Limit of quantification (LOQ) for both CQ and DECQ was accepted as 50ng/ml using 80μl DBS sample and 25ng/ml using 150μl whole blood sample. The mean recoveries for CQ, DECQ and internal standard for both whole blood and DBS were between 74 and 87%. The method was successfully applied for a pharmacokinetic study of CQ and DECQ in patients with Plasmodium vivax. Excellence correlation (r =0.997) was observed between the analysis of both CQ and DECQ in paired whole blood and DBS samples. [Copyright &y& Elsevier]

This work describes the analysis of both target and non-target compounds in paper and cardboard materials together with the characterization of their migration to Tenax® by means of liquid chromatography coupled to both low (LC-QqQ) and high resolution tandem mass spectrometry (LC-q-Orbitrap), respectively. To this aim, an entire analytical procedure was fully developed and validated for both matrices: paper/cardboard and Tenax®. A total of 97 chemicals, including photoinitiators, phthalates, biocides, antioxidants, etc., listed by the European Regulation, were found in the materials under study together with other substances not included in this list. Moreover, the majority of annotated substances were present in the simulant, giving evidence of their migration capacity. Migration percentages of 10 photoinitiators, 4 phthalates, bisphenol A, bis-(2-ethylhexyl) adipate, acetyltributyl citrate and caprolactam to Tenax® were quantified. Despite not exceeding the established specific migration limit (SML) in any case, benzophenone, 4-phenylbenzophenone and bisphenol A concentrations in some paper and cardboard materials were very close to the SML values established by the EU legislation. Image 1 • Target and non-target analysis was performed on paper and cardboard (P/B) materials. • LC-QqQ and LC-q-Orbitrap were used for target and non-target analysis, respectively. • Tenax was used for migration experiments simulating long-term storage of dry foods. • 97 compounds were annotated in the studied FCMs being most of them present in Tenax. • This work highlights the necessity of a specific regulation for P/B FCMs. [ABSTRACT FROM AUTHOR]

A bioanalytical method for the determination of piperaquine in 100 μL blood applied onto sampling paper, by solid-phase extraction and liquid chromatography, has been developed and validated. Blood spots were cut into small pieces prior to addition of 0.3 M perchloric acid, acetonitrile and phosphate buffer containing an internal standard. The liquid phase was loaded onto a mixed phase cation-exchange (MPC) solid-phase extraction column. Piperaquine and the internal standard were analysed by liquid chromatography and separated on a Chromolith Performance (100 mm × 4.6 mm) column with acetonitrile:phosphate buffer pH 2.5, I = 0.1 (8:92, v/v) at the flow of 3.5 mL/min. The UV detection was performed at 345 nm. The intra-assay precision was 12.0% at 0.150 μM, 7.3% at 1.25 μM and 7.3% at 2.25 μM. The inter-assay precision was 1.8% at 0.150 μM, 5.2% at 1.25 μM and 2.8% at 2.25 μM. The lower limit of quantification (LLOQ) was determined to 0.050 μM where the precision was 14.7%. [Copyright &y& Elsevier]

A simple high-performance liquid chromatographic method for the simultaneous analysis of quinine and 3-hydroxyquinine in blood samples dried on filter paper is described. Sample preparation involves liquid–liquid extraction with toluene–butanol 75:25 (v/v) followed by evaporation. A reversed-phase liquid chromatography system with fluorescence detection was used. The limit of determination was 10 nM for both quinine and 3-hydroxyquinine and the recovery varied between 78 and 109%. The within- and between-assay coefficients of variation varied between 2–5% and 4–10%, respectively. No loss of either analyte occurred after storage for 2 months at room temperature or at 37 °C. This method for sampling has advantages that make it of great value for clinical and pharmacokinetic studies especially in remote regions where storage and transportation is problematic. [Copyright &y& Elsevier]

A simple, low-cost, sensitive and selective LC method was developed for the determination of enrofloxacin and ciprofloxacin in chicken blood. The method was applied to whole blood from a chicken using dried blood spots on filter paper disks. The detection limits of enrofloxacin and ciprofloxacin (100 μl of whole blood on a disk) were 0.005 and 0.01 μg/ml, respectively. The whole procedure was verified in intra-laboratory studies (recoveries of both compounds were above 90%), and its applicability was tested with blood from the chicken receiving enrofloxacin in a single oral dose at a level of 10 mg/kg body mass. The method permits the use of a small volume of blood from a chicken and should be useful for pharmacokinetic studies. [ABSTRACT FROM AUTHOR]

A method using solid-phase extraction and high-performance liquid chromatography is evaluated for the simultaneous determination of sulfadoxine and pyrimethamine from 0.1 ml of whole blood dried onto filter paper. Extraction recoveries are about 60% for both drugs. The coefficient of variation for intra-assay precision, inter-assay precision and accuracy is less than 10% for sulfadoxine (10–100 μg/ml) and pyrimethamine (1–10 μg/ml). [Copyright &y& Elsevier]

Abstract: Lactic acidemia is commonly associated with severe diseases in pediatric patients. Quantitation of blood lactate and pyruvate is important for the diagnosis and clinical management. A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method using dried blood spots (DBS) was developed and could be used for simultaneous quantification of blood lactate and pyruvate. The applicability of the developed method was tested and confirmed by the regression analysis between LC–MS/MS method and enzymatic assay. Lactate and pyruvate were extracted from DBS obtained from 580 full-term, 120 pre-term infants (gestations ranging from 24 to 36 weeks), and 65 patients with suspected lactic acidemia, with methanolic internal standard (IS) solutions of sodium l-lactate-13C3 and pyruvate-13C3. An API-2000 LC–MS/MS system with multiple reaction monitoring (MRM) mode was applied. The within-run and between-run precisions (CV%) were determined and the results were 1.9% and 3.9% for lactate (n =20) and 5.7% and 7.3% for pyruvate (n =20). The linearity of lactate (r =0.9986) and pyruvate (r =0.9973) based on the IS was excellent. The parameter r squared (r 2) of linear regression between LC–MS/MS method and enzymatic assay was 0.9405 for lactate and 0.9447 for pyruvate, respectively, and the agreement between these methods was consistent and acceptable. The stability of lactate and pyruvate on DBS was also confirmed. The LC–MS/MS method we developed is a specific, sensitive, and reproducible method for measuring blood lactate and pyruvate concentrations. The use of DBS in this method makes it particularly attractive for pediatric patients. [Copyright &y& Elsevier]

Acute intoxication incidents due to neurotoxic organophosphate (OP) insecticides are occasionally reported, related either to suicidal attempts or occupational exposure due to the misuse of protective equipment. Among them, chlorpyrifos is a compound related to great controversy, which is still authorized and easily accessible in many countries around the world. However, to screen for its exposure markers, instrumental methods are commonly applied, which cannot enable rapid monitoring at an early stage of an intoxication. Therefore, in this study, a microfluidic paper-based analytical device (μPAD) able to rapidly screen for chlorpyrifos-oxon, the toxic chlorpyrifos metabolite, in human serum was developed and fully validated. The μPAD combines wax-printed butyrylcholinesterase (BChE) paper sensors, a lab-on-a-chip (LOC) prototype injector and a smartphone as the analytical detector. In principle, the wax-printed strips with adsorbed BChE are embedded into LOC injectors able to deliver samples and reagents on-demand. A smartphone reader was used to monitor the color development on the strips providing binary qualitative results. μPAD method performance characteristics were thoroughly evaluated in terms of specificity, detection capability (CCβ) and ruggedness. The developed analytical platform is rapid (results within 10 min), cost-efficient (0.70 €), potentially applicable at the point-of-need and attained a low CCβ (10 μg L−1 in human serum). Finally, μPAD characteristics were critically compared to well-established methods, namely an in-house BChE microplate assay and liquid chromatography tandem mass spectrometry. Image 1 • A hybrid μPAD with a smartphone readout was designed, fabricated and developed. • Sensitive, rapid and cheap chlorpyrifos-oxon screening in human serum was achieved. • μPAD performance was evaluated following the EU legislation on qualitative method validation. • The developed assay can be used as a complementary early warning tool in OP intoxication incidents. [ABSTRACT FROM AUTHOR]

Abstract: A method has been developed for the determination of 24 household high production volume (HPV) chemicals in municipal wastewater systems using solid-phase extraction (SPE) and analyses using both gas chromatography and liquid chromatography, each with tandem mass spectrometry (GC–MS/MS and LC–MS/MS). Target compounds include pesticides, antioxidants, fragrances, plasticizers, preservatives and personal care products. Method reporting limits ranged from 0.1 to 100ng/L in water and recoveries for most compounds were between 54 and 112%. Household HPVs were consistently detected in raw sewage entering three full-scale wastewater treatment plants. Compounds such as vanillin, DEET, benzophenone, 3-indolebutyric acid, bisphenol A, triclosan and triclocarban were detected in all wastewater influent and effluent samples, but were significantly lower in the effluent. Many of the remaining compounds were detected in the influent, but below detection in effluent samples. Menthol and phenoxyethanol had the highest observed concentrations in influent samples ranging from 1.5 to 13μg/L for menthol, and 8.8 to 22μg/L for phenoxyethanol. MGK-11, methylresorcinol, trifluralin, hexabromododecane, acriflavin and atrazine were not detected in any samples. The method described here detects a broad range of HPV chemicals with great sensitivity and selectivity. [Copyright &y& Elsevier]

The detection of nitazenes in biological fluids is increasingly needed as they are repeatedly reported in intoxication and overdose cases. A simple method for the quantification of low levels of nine nitazene analogs and brorphine in Dried Blood Spots (DBS) was developed and validated. 10 μL of spiked whole blood is deposited on a Capitainer®B card and allowed to dry. The spot is punched out, and extracted with 500 μL methanol:acetonitrile (3:1 v/v) added with 1.5 μL of fentanyl-D5 as the internal standard. After stirring, sonication, and centrifugation of the vial, the solvent is dried under nitrogen, the extract is reconstituted in 30 μL methanol, and 1 μL is injected into a UHPLC-MS/MS instrument. The method validation showed linear calibration in the 1–50 ng/mL range, LOD values ranging between 0.3 ng/mL (isotonitazene) and 0.5 ng/mL (brorphine), average CV% and bias% within 15 % and 10 % for all compounds, respectively. The matrix effect due to blood and filter paper components was within 85–115 % while recovery was between 15–20 %. Stability tests against time and temperature showed no significant variations for storage periods up to 28 days. Room temperature proved to represent the best samples storage conditions. UHPLC-MS/MS proved capable to reliably identify all target analytes at low concentration even in small specimen volumes, as those obtained from DBS cards, which in turn confirmed to be effective and sustainable micro-sampling devices. This procedure improves the efficiency of toxicological testing and provides an innovative approach for the identification of the nitazene class of illicit compounds. • An innovative approach for the identification of nitazenes and brorphine is presented. • Quantitative determination of 10 new synthetic opioids in DBS was achieved. • The stability of nitazenes in spiked DBS samples was evaluated. • Monitoring the diffusion of opioids in selected populations is possible. [ABSTRACT FROM AUTHOR]

Separation analytical methods, including liquid chromatography (LC) and capillary electrophoresis (CE), in combination with an appropriate detection technique, are dominant and powerful approaches preferred in the analysis of pharmaceutical and biomedical samples. Recent trends in analytical methods are focused on activities that push them to the field of greenness and sustainability. New approaches based on the implementation of greener solvents, non-hazardous chemicals, and reagents have grown exponentially. Similarly, recent trends are pushed in to the strategies based on miniaturization, reduction of wastes, avoiding derivatization procedures, or reduction of energy consumption. However, the real greenness of the analytical method can be evaluated only according to an objective and sufficient metric offering complex results taking into account all twelve rules of green analytical chemistry (SIGNIFICANCE mnemonic system). This review provides an extensive overview of papers published in the area of development of green LC and CE methods in the field of pharmaceutical and biomedical analysis over the last 5 years (2019–2023). The main focus is situated on the metrics used for greenness evaluation of the methods applied for the determination of bioactive agents. It critically evaluates and compares the demands of the real applicability of the methods in quality control and clinical environment with the requirements of the green analytical chemistry (GAC). Greenness and practicality of the summarized methods are re-evaluated or newly evaluated with the use of the dominant metrics tools, i.e., Analytical GREEnness (AGREE), Green Analytical Procedure Index (GAPI), Blue Applicability Grade Index (BAGI), and Sample Preparation Metric of Sustainability (SPMS). Moreover, general conclusions and future perspectives of the greening procedures and greenness evaluation metrics systems are presented. This paper should provide comprehensive information to analytical chemists, biochemists, and it can also represent a valuable source of information for clinicians, biomedical or quality control laboratories interested in development of analytical methods based on greenness, practicality, and sustainability. [Display omitted] • Recent trends in green analytical chemistry evaluation metrics. • Greenness and sustainability of CE and LC methods. • Green LC and CE methods in analysis of pharmaceutical and biomedical samples (2019–2023). • Recent trends and future perspectives of green analytical chemistry metrics. [ABSTRACT FROM AUTHOR]

• An alternative elution mode to conventional HPLC to separate compounds by class. • Sequential elution was utilized to separate classes of compounds in under 15 min. • A tandem-column stationary phase combination (SAX and C18) was utilized. • SAX+C18 and C18+SAX column orientations yielded nearly identical separations. • Retention time and peak area precision were below 1.5 % RSD. This paper discusses the development of an analytical method by an alternative separation approach, sequential elution liquid chromatography (SE-LC), to separate permanently charged ions (anions), weak acids, and neutral compounds using anion exchange and reversed-phase columns in tandem. SE-LC separates classes of compounds by group by employing two or more elution modes. Advantages to using SE-LC over conventional HPLC are a greater peak capacity and a reduced separation disorder. Importantly, the same HPLC as used for a conventional HPLC separation may be used to afford a successful SE-LC separation. Mobile phase selection and gradient optimization are integral for a successful SE-LC class separation of permanent anions, weak acids, and neutral compounds and will be discussed in detail in this paper. The most successful (best resolution and repeatability) SE-LC separation was achieved by applying isocratic elution at low pH to elute the weak acids, followed by an acetonitrile gradient to elute the neutral compounds, and last a sodium methanesulfonate gradient to elute the anionic compounds using a superficially porous C18 column coupled with a strong anion exchange (SAX) column. Repeatability (RSD) in the retention times and peak areas of the analytes was less than 0.25 % and 1.5 %, respectively. [ABSTRACT FROM AUTHOR]

• A data-driven model for reversed phase selectivity is established. • A revised hydrophobic subtraction model is proposed. • Accurate predictions of isomer selectivity are made. Reversed-phase (RP) liquid chromatography is an important tool for the characterization of materials and products in the pharmaceutical industry. Method development is still challenging in this application space, particularly when dealing with closely-related compounds. Models of chromatographic selectivity are useful for predicting which columns out of the hundreds that are available are likely to have very similar, or different, selectivity for the application at hand. The hydrophobic subtraction model (HSM1) has been widely employed for this purpose; the column database for this model currently stands at 750 columns. In previous work we explored a refinement of the original HSM1 (HSM2) and found that increasing the size of the dataset used to train the model dramatically reduced the number of gross errors in predictions of selectivity made using the model. In this paper we describe further work in this direction (HSM3), this time based on a much larger solute set (1014 solute/stationary phase combinations) containing selectivities for compounds covering a broader range of physicochemical properties compared to HSM1. The molecular weight range was doubled, and the range of the logarithm of the octanol/water partition coefficients was increased slightly. The number of active pharmaceutical ingredients and related synthetic intermediates and impurities was increased from four to 28, and ten pairs of closely related structures (e.g., geometric and cis -/ trans - isomers) were included. The HSM3 model is based on retention measurements for 75 compounds using 13 RP stationary phases and a mobile phase of 40/60 acetonitrile/25 mM ammonium formate buffer at pH 3.2. This data-driven model produced predictions of ln α (chromatographic selectivity using ethylbenzene as the reference compound) with average absolute errors of approximately 0.033, which corresponds to errors in α of about 3 %. In some cases, the prediction of the trans -/ cis - selectivities for positional and geometric isomers was relatively accurate, and the driving forces for the observed selectivity could be inferred by examination of the relative magnitudes of the terms in the HSM3 model. For some geometric isomer pairs the interactions mainly responsible for the observed selectivities could not be rationalized due to large uncertainties for particular terms in the model. This suggests that more work is needed in the future to explore other HSM-type models and continue expanding the training dataset in order to continue improving the predictive accuracy of these models. Additionally, we release with this paper a much larger data set (43,329 total retention measurements) at multiple mobile phase compositions, to enable other researchers to pursue their own lines of inquiry related to RP selectivity. [ABSTRACT FROM AUTHOR]

• A LC system was constructed with a miniaturized photometric detector and a microfluidic chip. • The Z-shaped cell design increases the effective optical path length. • The Z-shaped cell and column are on the same chip without a pipeline connection. • The microchip can be filled with cation exchange resin and C18 particles. In recent years, miniaturized analytical instruments have been developing to meet the needs of portable and rapid analysis. The key of miniaturized analytical equipment is the miniaturization and integration of functional modules. This paper aims to develop a miniaturized photometric detector and separation microfluidic chip for a liquid chromatography (LC) system. The detector uses a light-emitting diode to emit ultraviolet light, which is collimated by an internal double lens. A Z-shaped flow cell with a long optical path is designed and fabricated in the separation microfluidic chip with a three-layer structure, which provides a tubing-free connection between the separation and detection unit. Detector performance is evaluated using hemoglobin (Hb) samples, with an upper limit of detection linearity (95 %) of 0.345 AU and stray light level as low as 0.08 %. Additionally, the microchip channel can be filled with cation exchange resin and C18 particles. Finally, an ion LC system and a reversed-phase LC system were constructed based on the miniaturized photometric detector and two microchips with different packed columns, respectively, and were successfully used in the separation and detection of two metabolic markers (glycated hemoglobin or bilirubin). The results of this study are expected to facilitate the development of a portable LC system and their application in community health services and family health management of chronic diseases. [ABSTRACT FROM AUTHOR]

The combination of post-column derivatization (PCD) and liquid chromatography (LC) has become a promising technique for enhancing detection sensitivity and selectivity, while simultaneously facilitating rapid and automated analysis. This paper presents a comprehensive review of PCD techniques spanning from 2013 to 2023, focusing on LC-UV-Vis/fluorescence spectrometry and LC-mass spectrometry detection methods. It encompasses an array of PCD methods, including chemical, photochemical, and electrochemical derivatization, as well as post-column complexation. This review delves deeply into key areas, exploring the underlying principles of derivatization, examining the current applications of classical PCD methods, and shedding light on emerging derivatization reactions. The review also provides remarks and insights into future directions, offering a perspective on the evolving landscape of the field. The overarching goal is to equip researchers with innovative ideas and strategies for PCD, thereby enhancing the practical application and utility of this technology in scientific research. [Display omitted] • LC coupled PCD enhances detection sensitivity/selectivity. • Chemical/photochemical/electrochemical reactions and complexation are the main methods. • Advances in post-column derivatization techniques from 2013 to 2023 are reviewed. • Principles of derivatization reaction and their applications are examined. • Insights on future trends advancing post-column derivatization research are offered. [ABSTRACT FROM AUTHOR]

• The in situ growth method was employed to prepare COF-TpPa-1@SiO 2 microspheres. • The microspheres can be used as RP/HILIC mixed-mode stationary phase. • The stationary phase exhibited excellent resolution in separating small solutes. • The stationary phase can enhance the aromatic, shape and planar selectivity. Covalent organic frameworks (COFs) show promise as a stationary phase in high performance liquid chromatography (HPLC). However, there are only a few COFs-based stationary phases developed for HPLC separation so far. Therefore, it is crucial to not only develop more varieties of COFs-type stationary phases for HPLC separation, but also to explore the retention mechanism of solutes on these stationary phases. In this paper, a new in-situ growth method was developed to prepare β -ketoenamine COF-TpPa-1@SiO 2 composite microspheres, using spherical silica as the core material and COF-TpPa-1 fabricated by covalent conjugation of 1,3,5-triformylphloroglucinol (Tp) and p -phenylenediamine (Pa-1) as the COF shells. The resulting microspheres exhibit uniform morphology, good monodispersity, large specific surface area, narrow size distribution, and high stability. Due to diverse functional groups in the structure of COF-TpPa-1, the microspheres can offer multiple interactions, such as hydrophobic, π-π stacking and electron-donor–acceptor (EDA) between COFs and analytes. As a result, the COF-TpPa-1@SiO 2 composite microspheres can be used as a mixed-mode stationary phase for HPLC separation. The chromatographic performance and retention mechanism of the COF-TpPa-1@SiO 2 packed column were investigated by separating polar and non-polar solutes, as well as isomers, in various HPLC modes, including reversed-phase liquid chromatography (RPLC), hydrophilic interaction chromatography (HILIC), and RPLC/HILIC mixed-mode chromatography. The results showed successful separation of non-polar alkylbenzene homologues, polycyclic aromatic hydrocarbons (PAHs), and polar amines and phenols in RPLC mode. The "U-shaped" curves of retention factor with the ACN concentration in mobile phase for four nucleobases indicated that the solute retention on the column followed a mixed mode mechanism of RPLC/HILIC. Compared to a traditional C18 column, the COF-TpPa-1@SiO 2 column exhibited superior separation efficiency, stability, repeatability and reproducibility in the separation of analytes with different polarities. The column enhanced the aromatic, shape and planar selectivity for PAHs and isomers through π-π interaction and improved the separation efficiency for electron-deficient compounds due to EDA effect. At last, the column was successfully used to separate and detect the residues of 5 phenylurea herbicides (PUHs) in soil. All these results indicate the potential of COFs for chromatography applications. [ABSTRACT FROM AUTHOR]

Modified messenger RNA (mRNA) represents a rapidly emerging class of therapeutic drug product. Development of robust stability indicating methods for control of product quality are therefore critical to support successful pharmaceutical development. This paper presents an ion-pair reversed-phase liquid chromatography (IP-RPLC) method to characterise modified mRNA exposed to a wide set of stress-inducing conditions, relevant for pharmaceutical development of an mRNA drug product. The optimised method could be used for separation and analysis of large RNA, sized up to 1000 nucleotides. Column temperature, mobile phase flow rate and ion-pair selection were each studied and optimised. Baseline separations of the model RNA ladder sample were achieved using all examined ion-pairing agents. We established that the optimised method, using 100 mM Triethylamine, enabled the highest resolution separation for the largest fragments in the RNA ladder (750/1000 nucleotides), in addition to the highest overall resolution for the selected modified mRNA compound (eGFP mRNA, 996 nucleotides). The stability indicating power of the method was demonstrated by analysing the modified eGFP mRNA, upon direct exposure to heat, hydrolytic conditions and treatment with ribonucleases. Our results showed that the formed degradation products, which appeared as shorter RNA fragments in front of the main peak, could be well monitored, using the optimised method, and the relative stability of the mRNA under the various stressed conditions could be assessed. [Display omitted] • Key parameters evaluated for separation of large RNA, using IP-RPLC • Method enabled baseline separation of RNA fragments, sized between 100 – 1000 bases • Rapid high resolution analysis method for modified mRNA developed • Study of mRNA stability upon exposure to heat, hydrolytic conditions and RNases • Degradation mapping using mRNA model compound with optimised LC method [ABSTRACT FROM AUTHOR]

Hydrophilic Interaction Liquid Chromatography (HILIC) is an outstanding strategy for the challenging analysis of hydrophilic and polar components. Nevertheless, analysis under HILIC mode typically consumes 70%–95 % acetonitrile with the disadvantage of high analytical costs, being environmentally unfriendly and causing biohazards, which is not in line with the concept of green chromatography. Research has shown that Per Aqueous Liquid Chromatography (PALC) simultaneously emphasizes efficient analytical performance for hydrophilic analytes and green analytical concepts. The development of new PALC stationary phases with superior performance is necessary. In this paper, silanized silica was sequentially subjected to esterification reaction, polymerization reaction and covalent bonding through five steps to obtain SiO 2 -RHP-AuNPs material, which was prepared as a novel stationary phase for PALC. Comprehensive characterization of the materials by means of Fourier transform infrared spectroscopy, Transmission scanning electron microscope, Elemental analysis and Thermogravimetric analysis showed the successful bonding of the functionalized groups on the original silica. The polymeric stationary phase based on Radix hedysari polysaccharide and Au nanoparticles had higher density of hydroxyl and ester functionalized groups. The Au nanoparticles upgraded their mesoporous structure and thermal stability, providing exceptional chromatographic performance and selectivity for chromatographic analysis. The influence of mobile phase water content, salt concentration, pH and column temperature on the retention behavior was evaluated. The novel Column was found to exhibit a dual mechanism of hydrophobic interactions/ion exchange interactions in a mobile phase with high water content. The separation efficiency and selectivity of SiO 2 -RHP-AuNPs columns for synthetic pigments and organic acids in PALC mode were superior to those of commercial HILIC and C 18 columns. In addition, a method for the determination of seven active ingredients in Fructus Ligustri Lucidi by SiO 2 -RHP-AuNPs column in PALC mode was developed. The method had good stability, reproducibility and accuracy, which was capable of realizing the quality evaluation of Chinese Materia Medicas. [Display omitted] • Per aqueous liquid chromatography conformed to green chromatography. • The new stationary phase featured strong hydrophilicity and thermal stability. • The novel SiO 2 -RHP-AuNPs columns showed good stability and reproducibility. • Hydrophilic compositions were analyzed with favorable separation performance. • The developed method was applied for quality control in Chinese Materia Medicas. [ABSTRACT FROM AUTHOR]

This paper employed a physiologically based pharmacokinetic model (PBPK) to investigate the transformations of folic acid and its metabolites in vivo. Additionally, an ultra-performance liquid chromatography (UPLC) method was developed to accurately measure the body's retention rate and conversion rate of folic acid, tetrahydrofolate, and 5-methyltetrahydrofolate. Furthermore, the bioavailability of folic acid in the body was assessed by combining this method with an evaluation technique for animal models. The study found that the gastric metabolism time was 2 h, while the small intestinal metabolism duration was 4 h. The maximum conversion rate was observed in plasma and liver after 6 h, and in the brain after 8 h. This serves as a framework for creating a model to assess the bioavailability of folic acid in living organisms, to enhance the safety and efficacy of folic acid intake. • Establishment of UPLC assay for folic acid and its derivatives. • Metabolic absorption and tissue distribution of folic acid in the body. • Bioavailability of folic acid at different time intervals in the body. [ABSTRACT FROM AUTHOR]

Colorimetric sandwich-type biosensors that can both provide sensitivity competitive with fluorescence-based approaches, and leverage reagents that are cost-effective, widely available and as safe as possible, are highly sought after. Herein, we demonstrate an alternative highly-sensitive colorimetric method for paper-based sandwich-type biosensing that uses starch–iodide complexation to simplify practical biosensing using ubiquitous reagents. Targeting the mycotoxin ochratoxin A (OTA), a covalently-immobilised OTA antibody on a cellulose surface captures OTA and forms a sandwich with OTA aptamer-conjugated glucose oxidase. Adding the chromogenic reagents at an optimized concentration, a distinct blue color develops within 30 min, offering excellent contrast with the clear/white of the negative sample. With a sampling volume down to just 5 μL, the assay exhibits concentration limits of detection and quantitation of 20 and 320 pg mL−1, respectively, and a linear range from 10−1 to 105 ng mL−1 (R2 = 0.997). The method displays excellent selectivity against related mycotoxins, excellent %recovery (95–117%) and robust operation in complex matrices (beer, urine and human serum), with no significant difference versus gold-standard liquid chromatography. Along with its excellent analytical performance, this assay benefits from non-toxic and extremely cheap reagents that can be safely disposed of in the field, and presents an attractive alternative to toxic dyes and nanoparticles. Image 1 • Novel colorimetric antibody-aptamer sandwich assay using starch-iodine complexation. • Central composite design for fast and efficient sensor optimization. • Ultrasensitive detection of OTA using PADs with LoD of 20 pg mL−1 using 5 μL. • Applied for OTA detection in beverages, urine and human serum. [ABSTRACT FROM AUTHOR]

This review critically discusses the developments on open-tubular liquid chromatography (OT-LC) and open-tubular capillary electrochromatography (OT-CEC) during 2014–2018. An appropriate Scopus search revealed 5 reviews, 4 theoretical papers on open-tubular format chromatography, 29 OT-LC articles, 68 OT-CEC articles and 4 OT-LC/OT-CEC articles, indicating a sustained interest in these areas. The open-tubular format typically uses a capillary column with inner walls that are coated with an ample layer or coating of solid stationary phase material. The ratio between the capillary internal diameter and coating thickness (CID/CT) is ideally ≤ 100 for appropriate chromatographic retention. We, therefore, approximated the CID/CT ratios and found that 22 OT-LC papers have CID/CT ratios ≤100. The other 7 OT-LC papers have CID/CT ratio >100 but have clearly demonstrated chromatographic retention. These 29 papers utilised reversed phase or ion exchange mechanisms using known or innovative solid stationary phase materials (e.g. metal organic frameworks), stationary pseudophases from ionic surfactants or porous supports. On the other hand, we found that 68 OT-CEC papers, 7 OT-LC papers and 4 OT-LC & OT-CEC papers have CID/CT ratios >100. Notably, 44 papers (42 OT-CEC and 2 OT-LC & OT-CEC) did not report the retention factor and/or effective electrophoretic mobility of analytes. Considering all covered papers, the most popular activity was on the development of new chromatographic materials as coatings. However, we encourage OT-CEC researchers to not only characterise changes in the electroosmotic flow but also verify the interaction of the analytes with the coating. In addition, the articles reported were largely driven by stationary phase or support development and not by practical applications. Image 1 • Developments in OT-LC and OT-CEC during 2014–2018 were critically reviewed. • Appropriate coating thickness inside narrow capillaries were implemented in OT-LC. • Lack of rigour in reporting the chromatographic effect of coatings in OT-CEC. • OT-LC and OT-CEC are still in the exploratory or research phase. • Focus was on development of innovative stationary phase materials and supports. [ABSTRACT FROM AUTHOR]

In the study of ancient diet, lipid analysis of archaeological pottery residues has become a major investigative tool. Lipids absorb readily into clay vessels during cooking or processing of foodstuffs and are preserved, although not completely unchanged, for millennia. These can be linked directly to plant and animal resources used by past societies and can be valuable for understanding culinary practices, diet, and foodways. Identifying 'old food' via organic residue analysis has steadily developed since its inception last century, but growth has intensified in the past several years in many areas from modern reference comparisons to data interpretation. This paper will discuss current developments in the field of dietary studies using archaeological lipid analysis. Advancements in extraction methods, instrumentation, experimental ground-truthing, data processing, and interpretive frameworks are significantly boosting the explanatory power of lipid analysis for reconstructing ancient foodways and amplifying the importance of biomolecular-level data even further. • Lipids in archaeological ceramics provide information about past human diet. • New instrumental approaches provide higher sensitivity and coverage. • Reference and cooking experiments are pivotal for reliable identification of commodities. • Advanced analytical techniques and interpretive frameworks enable us to address new and complex research questions. [ABSTRACT FROM AUTHOR]

Microfluidic and capillary devices are increasingly being used in analytical applications while their overall size keeps decreasing. Detection sensitivity for these microdevices gains more importance as device sizes and consequently, sample volumes, decrease. This paper reviews optical, electrochemical, electrical, and mass spectrometric detection methods that are applicable to capillary scale and microfluidic devices, with brief introduction to the principles in each case. Much of this is considered in the context of separations. We do consider theoretical aspects of separations by open tubular liquid chromatography, arguably the most potentially fertile area of separations that has been left fallow largely because of lack of scale-appropriate detection methods. We also examine the theoretical basis of zone electrophoretic separations. Optical detection methods discussed include UV/Vis absorbance, fluorescence, chemiluminescence and refractometry. Amperometry is essentially the only electrochemical detection method used in microsystems. Suppressed conductance and especially contactless conductivity (admittance) detection are in wide use for the detection of ionic analytes. Microfluidic devices, integrated to various mass spectrometers, including ESI-MS, APCI-MS, and MALDI-MS are discussed. We consider the advantages and disadvantages of each detection method and compare the best reported limits of detection in as uniform a format as the available information allows. While this review pays more attention to recent developments, our primary focus has been on the novelty and ingenuity of the approach, regardless of when it was first proposed, as long as it can be potentially relevant to miniature platforms. [Display omitted] • Covers open and packed capillary HPLC, capillary and μchip electrophoretic platforms. • Optical, Electrochemical and mass spectrometric detection. • Recent coverage on applications but includes classic groundbreaking articles. • Provides a detailed tabulation of topical reviews in last 12 years. • Provides attainable and typical limits of detection for most approaches. [ABSTRACT FROM AUTHOR]

• Three imidazole- and C18- bifunctional silica stationary phases (Sil-Im-C18) were prepared. • Chromatographic performance can be adjusted by the control of different co-grafting amounts of C18 chain and imidazole group. • The prepared stationary phases can be used in reversed-phase liquid chromatography (RPLC) and ion exchange chromatography (IEC). • Excellent separation performance for PAHs, phenylesters, phenylamines, phenols and inorganic anions was obtained. • Nucleobases and nucleosides can be separated using pure water as mobile phases. In this paper, three imidazole- and C18- bifunctional silica stationary phases (Sil-Im-C18) were prepared by adjusting introduction interval of octadecyltrichlorosilane (ODS) and 3-imidazol-1-ylpropyl(trimethoxy)silane (TMPImS), which can be used for reversed-phase liquid chromatography (RPLC) and ion exchange chromatography (IEC) with adjustable performance. The successful preparation of Sil-Im-C18 were confirmed by the characterizations of elemental analysis, infrared spectroscopy (FTIR) and contact angle (CA). Chromatographic performance of Sil-Im-C18 were evaluated by the separation of Tanaka test mixture, alkylbenzenes, linear PAHs and a set of analytes with different properties (uracil, phenol, 1,2-dinitrobenzene and naphthalene), and compared with commonly used C18 column. It was found that the chromatographic performance of Sil-Im-C18 changed significantly with the difference in bonding amount of imidazole and C18. Sil-Im-C18 demonstrated the excellent separation performance towards polycyclic aromatic hydrocarbons (PAHs), phenylesters, phenylamines, phenols and inorganic anions, and notably, nucleobases and nucleosides can be separated using pure water as mobile phases. The van Deemter plot showed that the column efficiency of Sil-Im-C18-3 was 64,933 plate· m −1 for naphthalene, indicated that Sil-Im-C18 was reasonably chromatographic columns. The RSD values of retention time were 0.22 %-0.61 % for 10 needles alkylbenzenes injected continuously at 50 °C to investigate thermal stability and repeatability, all the fluctuations of k of naphthalene were less than 2.3 % for Sil-Im-C18-1 during flushing 24 h with the mobile phase at different pH values (pH = 3 and 8), the retention time of alkylbenzenes were almost same for Sil-Im-C18-1 at different time, the RSD values of retention time of alkylbenzenes were 0.45 %-2.28 % for two batches Sil-Im-C18-1, revealing the excellent repeatability, thermal stability, durability and reproducibility of Sil-Im-C18, and implying a commercial prospect. [ABSTRACT FROM AUTHOR]

Per-poly fluoroalkyl substances (PFASs) are a group of synthetic fluorine compounds used in food packaging materials to repel water and fats. This study assessed the chemical migration of PFAS from different food contact materials, including cardboard, recycled cardboard, biopolymer, paper and Teflon trays, from various markets. Migration assays were conducted using Tenax® as a food simulant, which was optimized by subjecting it to three consecutive extractions with 3 mL of ethanol within an hour. The resulting extractions were combined and concentrated to 0.5 mL using a nitrogen stream. The analysis was performed using ultrahigh performance liquid chromatography (UPLC) coupled with ion-mobility (IMS) quadrupole-time-of-flight (QTOF) mass spectrometry, which provided a powerful and novel tool for identifying a library of targets containing collision cross section values (CCS) and increasing confidence in subsequent identifications. Eleven PFAS compounds belonging to the family of perfluorocarboxylic acid, perfluorosulfonic acid and perfluorooctanesulfonamidoacetic acid substances (PFCAs, PFSAs and FOSAAs) were found in packaging samples obtained from China, with migrant concentrations ranging 3.2 and 22.3 μg/kg. In contrast, no detectable levels of PFAS were observed in packaging samples obtained in Spain. All trays tested were deemed to be suitable for use as food contact materials due to the fact that their migrant values were lower than 0.025 mg/kg for PFOA and its salts, and lower than a maximum concentration of 1 mg/kg for PFOA-related compounds. [Display omitted] • A novel Ion-mobility QTOF mass spectrometry technique applied to migration of per and poly fluoroalkyl substances (PFAS). • Enabling a library of (PFAS) with their CCS values and characteristics fragments. • Migration study of thirteen food contact materials such as cardboard, recycled cardboard, biopolymer, paper and Teflon trays. • Eleven PFAS compounds were found in packaging samples obtained from China. • Migration values concentrations between 3.2 and 22.3 μg/kg. [ABSTRACT FROM AUTHOR]

• Dimethyl carbonate is tested as green alternative to acetonitrile. • Dimethyl carbonate is slightly soluble in water, but it has high elution strength. • Dimethyl carbonate and acetonitrile showed comparable kinetic performance. Nowadays, environmental problems are drawing the attention of governments and international organisations, which are therefore encouraging the transition to green industrial processes and approaches. In this context, chemists can help indicate a suitable direction. Beside the efforts focused on greening synthetic approaches, currently also analytical techniques and separations are under observation, especially those employing large volumes of organic solvents, such as reversed-phase liquid chromatography (RPLC). Acetonitrile has always been considered the best performing organic modifier for RPLC applications, due to its chemical features (complete miscibility in water, UV transparency, low viscosity etc); nevertheless, it suffers of severe shortcomings, and most importantly, it does not fully comply with Environmental, Health and Safety (EHS) requirements. For these reasons, alternative greener solvents are being investigated, especially easily available alcohols. In this work, chromatographic performance of the most common solvents used in reversed-phase chromatography, i.e., acetonitrile, ethanol and isopropanol, have been compared to a scarcely used solvent, dimethyl carbonate (DMC). The analytes of interest were two small molecules, caffeine and paracetamol, whose kinetics and retention behaviour obtained with the four solvents have been compared, and all contributions to band broadening have been assessed. Results about kinetic performance are very promising, indicating that a small amount (7 % v/v) of DMC is able to produce the same efficiency as a 2.5-times larger ACN volume (18 % v/v), and larger efficiency than alcohols. This paper reports, for the first time, fundamental studies concerning the mass transfer phenomena when DMC is used as an organic solvent in RPLC, and, together with the companion paper, represents the results of a research whose final aim was to discover whether DMC is suitable for chromatographic applications both in linear and preparative conditions. [ABSTRACT FROM AUTHOR]

Chiral separation remains an important area of research in analytical chemistry. This review recognises the use of different chiral selectors for chiral liquid chromatography and capillary electrochromatography. For the past two years (2017–2018), there was high activity in the development of chiral chromatographic materials and methods as shown by the 93 research and 9 review articles covered. Based on the covered papers, we categorised chiral selectors as low molecular mass, oligomeric, polymeric and metal/covalent organic framework entities. Popular research topics are on liquid chromatography (76 papers), new chiral selectors and stationary phases (56 papers) and polymeric chiral selectors (38 papers). Only 13 research articles were on applications and most papers were on fundamental studies that showed separation of racemic drugs and other model compounds. • Advances on chiral selectors in LC and CEC during 2017–2018. • The 93 papers covered suggested a high activity in this research area. • Classical low molecular mass, oligomeric and polymeric chiral selectors. • New metal/covalent organic framework chiral selectors. • Only 13 papers focused on applications. [ABSTRACT FROM AUTHOR]

Abstract This paper describes a case of medicine in disguise: seized tattoo inks containing lidocaine and tetracaine at high concentration. Identification of anaesthetics was performed by LC MS Q-TOF with ESI+ source, by accurate mass measurement and by comparing the fragmentation patterns of molecular ions, at 30 V and 10 V of collision-offset voltage, with reference standards. Quantification was also performed by LC MS Q-TOF on the chromatographic peaks in the extracted ion chromatograms, by calibration curves obtained at different standard concentrations and by standard additions approach. The measurement uncertainty was estimated from validation data. The paper gives also chromatographic parameters, MS and MS/MS data and a quantitation method, with a full validation, of other six "caines". Thus the paper intends to provide a tool for identification and quantitation of the most common local anaesthetics that could be fraudulently added to tattoo inks. The results here reported show that the seized samples of inks represent a serious health risk owing to the high anaesthetic content – therapeutic-like dosage – found. Graphical abstract A case of medicines in disguise is described: tattoo inks containing local anaesthetics. The paper reports the identification and quantification of lidocaine and tetracaine in tattoo inks samples. A MS and MS/MS Q-TOF method for identification and quantitation of eight caines in tattoo inks was validated. fx1 Highlights • A new case of medicine in disguise: seized tattoo inks containing local anaesthetics. • Identification and quantification of lidocaine and tetracaine by LC MS Q-TOF. • A mass spectrometric method for identification and quantitation of eight "caines" in tattoo inks. • High therapeutic dosages anaesthetics in tattoo inks: a risk for health. [ABSTRACT FROM AUTHOR]

Abstract Carnitines are diagnostic biomarkers of fatty acid oxidation defects and organic acidemias. Quantitative measurements of various carnitines in dried blood spot (DBS) have potential use in remote health applications for disease diagnosis and epidemiological surveillance. To provide an improved LC/multiple-reaction monitoring (MRM)-MS method for quantitation of carnitines in DBS, 3-nitrophenylhydrazine (3NPH) was tested as a high-efficiency chemical isotope-labeling reagent for pre-analytical derivatization of 24 routinely-analyzed species. Reaction conditions were optimized and carnitine structural isomers were separated by reversed-phase LC with positive-ion MRM/MS detection, giving on-column lower LOQs of sub- to low-femtomole levels. 13C 6 -3NPH was used to produce 13C 6 - or 13C 12 -labeled derivatives of the mono- and di-carboxylic carnitines in a "one-pot" reaction. These labeled analogues were used as stable isotope-labeled internal standards to compensate for possible ESI matrix effects. Combined with an optimized, two-step procedure for the extraction of carnitines from DBS, this isotope-labeling derivatizaiton - LC/MRM-MS method provided good linearity, high precision (intra-day CVs of ≤7.8% and inter-day CVs of ≤8.8%) and high accuracy (three levels of standard substances spiked in, with recoveries of 86.9%–109.7%) quantitation of carnitines in three sets of DBSs on cellulose or cotton filter paper. This method was then applied to determine the concentration changes of the analytes in the DBSs under two stability-testing regimes: 1) a one-time 4-h sunlight exposure and 2) a set of cycled temperature transitions (−20 °C for 2 days, 40 °C for 2 days, and back to −20 °C for 2 additional days). All of the carnitines showed good stabilities under the first testing condition. Under the second testing condition, free carnitine showed concentration increases of 9.3%–16.1%; acetyl carnitine, 3-OH butyryl carnitine, and malonyl carnitine showed concentration decreases of 12.2%–17.3%, 12.9%–17.1% and 10.7%–15.3%, respectively, and other 20 acyl carnitines showed concentration changes of <10% in three sets of DBSs on cellulose or cotton filter paper. These preliminary stability-testing results indicate a need to more systematically investigate the effects of various environmental conditions on the chemical stabilities of carnitines in DBS specimens if this sampling method is to be used in remote health applications. Graphical abstract Image 1 Highlights • Pre-analytical derivatization with 3-nitrophenylhydrazine (3NPH) was optimized for LC/MRM-MS of carnitines. • Use of a 2-step carnitine extraction and isotope-labeled ISs led to precise and accurate quantitation of 24 carnitines • 13C 6 -3NPH derivatives were used as ISs for calibration. • Measurements of carnitines in DBSs on cellulose or cotton-based paper showed good stabilities after 4-h sunlight exposure. • Concentration changes in several carnitines were observed after cycled temperature transitions during DBS storage. [ABSTRACT FROM AUTHOR]

Eucommia ulmoides Oliv. is a deciduous tree which contains various chemical ingredients. The main objective was to document the active chemical ingredients of Eucommia ulmoides Oliv. and their metabolic profiles in vivo, with a view to providing an experimental and theoretical basis for clarifying the mechanisms underlying the pharmacological activity of Eucommia ulmoides Oliv. against rheumatoid arthritis. Eight main active constituents of Eucommia ulmoides Oliv. bark (pinoresinol glucopyranoside, aucubin, geniposidic acid, geniposide, genipin, chlorogenic acid, quercetin and betulinic acid) were quantified using high-performance liquid chromatography (HPLC). This paper additionally identified and characterized prototype metabolites via ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) combined with the Human Metabolome Database (HMDB) and literature comparisons. Ultra pressure liquid chromatography-mass spectrometry/ mass spectrometry (UPLC-MS/MS) was subsequently employed to quantify these components in blood over time and evaluate their pharmacokinetic characteristics. The anti-rheumatoid arthritis effects of genipin, pinoresinol glucopyranoside and their combinations were assessed using in vitro cellular assays. We identified and characterized a total of 53 ingredients from Eucommia ulmoides Oliv. bark and plasma samples, among which 20 were confirmed as prototype metabolites. Meanwhile, this paper derived and analyzed the metabolic cleavage pathway of 8 index ingredients. Six of these compounds displayed rapid entry into blood, with high plasma exposure and fast elimination rates. Data from the in vitro cellular assay showed that aucubin, pinoresinol glucopyranoside, genipin, and combinations of these compounds effectively inhibit MH7A cell proliferation, reduce NO release, and decrease inflammatory factor levels. [Display omitted] [ABSTRACT FROM AUTHOR]

While Reinforcement Learning (RL) has already proven successful in performing complex tasks, such as controlling large-scale epidemics, mitigating influenza and playing computer games beyond expert level, it is currently largely unexplored in the field of separation sciences. This paper therefore aims to introduce RL, specifically proximal policy optimization (PPO), in liquid chromatography, and evaluate whether it can be trained to optimize separations directly, based solely on the outcome of a single generic separation as input, and a reward signal based on the resolution between peak pairs (taking a value between [ − 1 , 1 ]). More specifically, PPO algorithms or agents were trained to select linear (1-segment) or multi-segment (2-, 3-, or 16-segment) gradients in 1 experiment, based on the outcome of an initial, generic linear gradient (ϕ s t a r t = 0.3 , ϕ e n d = 1.0 , and t g = 20 min), to improve separations. The size of the mixtures to be separated varied between 10 and 20 components. Furthermore, two agents, selecting 16-segment gradients, were trained to perform this optimization using either 2 or 3 experiments, in sequence, to investigate whether the agents could improve separations further, based on previous outcomes. Results showed that the PPO agent can improve separations given the outcome of one generic scouting run as input, by selecting ϕ -programs tailored to the mixture under consideration. Allowing agents more freedom in selecting multi-segment gradients increased the reward from 0.891 to 0.908 on average; and allowing the agents to perform an additional experiment increased the reward from 0.908 to 0.918 on average. Finally, the agent outperformed random experiments as well as standard experiments (ϕ s t a r t = 0.0 , ϕ e n d = 1.0 , and t g = 20 min) significantly; as random experiments resulted in average rewards between 0.220 and 0.283, and standard experiments resulted in average rewards of 0.840. In conclusion, while there is room for improvement, the results demonstrate the potential of RL in chromatography and present an interesting future direction for the automated optimization of separations. • Proximal policy optimization (PPO) for the direct optimization of separations. • PPO agent learned to select multi-step gradients to optimize separations of mixtures. • PPO agent improved separations based on the outcome of initial linear gradients. [ABSTRACT FROM AUTHOR]

[Display omitted] • A UPLC method was firstly established to assay ten components in N. officinalis. • The content of ten phytochemicals in different parts of was greatly different. • Superior distribution and content of phytochemicals were found in the leaves. Nauclea officinalis is a Li-folk medicine in China, with antimalarial, antibacterial, and anti-inflammatory properties. However, the phytochemicals of Nauclea officinalis have not yet been comprehensively researched. In this paper, a reliable and efficient approach based on ultra-performance liquid chromatography (UPLC) with a diode array detector (DAD) was firstly established for simultaneous quantification of alkaloids, flavonoids, and phenolic acids in N. officinalis resources. The samples were extracted using ultrasound with 60 % ethanol for 20 min (1:50 g/mL), and analyzed by the developed UPLC-DAD method. Under the optimized extraction and chromatographic conditions, the proposed approach showed favorable performance in terms of the linearity (R2 > 0.9998), precision (RSD < 3.75 %), repeatability (RSD < 0.86 %), stability (RSD < 2.14 %), and accuracy (with the recovery rates between 95.15 % and 105.49 %) within an extremely short running time (12 min). Moreover, the developed approach was successfully employed in the quantification of ten phytochemicals in different parts (leaves, branches and trunks) of Nauclea officinalis. Based on analytical results, the content of ten phytochemicals in different organs of Nauclea officinalis was significantly different, and the superior contents of these phytochemicals were located in the leaves compared to the branches and trunks. In summary, the current work established an effective method for the assay of multi-compounds, which could supply a basis of the quality control and comprehensive utilization for Nauclea officinalis. [ABSTRACT FROM AUTHOR]