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• Unmodified paper is used for the isolation of biogenic amines from beer samples. • The analysis of the extracts by MS provides LODs as low as 0.06 mg L−1. • The simultaneous extraction of several samples and the short analysis time (2 min) increases the sample throughput. • Eight different beer samples have been analyzed by the standard addition method. While current trends in Green Analytical Chemistry aim at reducing or simplifying sample treatment, food usually comprises complex matrices where direct analysis is not possible in most cases. In this context, sample treatment plays a pivotal role. Biogenic amines are naturally formed in many foodstuffs due to the action of microorganisms, while their presence has been associated with adverse health effects. In this work, the extraction of seven biogenic amines (cadaverine, histamine, phenylethylamine, putrescine, spermidine, spermine, and tyramine) from beer samples has been simplified using laboratory filter paper as sorbent without any further modification. The analysis of the eluates by direct infusion mass spectrometry reduces the time of analysis, increasing the sample throughput. This simple but effective method enabled the determination of the analytes with limits of detection as low as 0.06 mg L−1 and relative standard deviations better than 11.9%. The suitability of the method has been assessed by analyzing eight different types of beers by the standard addition method. [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 the present paper, we report an improved ion-pair solid-phase extraction (IP-SPE) method for the analysis of alkylphosphonic acids, namely, methyl, ethyl and propylphosphonic acids, present in the aqueous sample. The aqueous sample was mixed with an ion-pair reagent, phenyltrimethylammonium hydroxide (PTMAH) and passed through activated charcoal SPE cartridge. The retained chemicals in the cartridge were extracted with methanol and analysed by gas chromatography–mass spectrometry (GC–MS) under the electron impact ionization (EI) mode. The analytes were converted to their methyl esters by pyrolytic methylation in the hot GC injection port. The recoveries of alkylphosphonic acids were above 95% and the minimum detection limits were as low as 10ng/mL. The recovery of the test chemicals was tested with solvents, dichloromethane, n-hexane, ethyl acetate, acetone, acetonitrile and methanol. The chemicals could be efficiently extracted by the hydrophilic solvents. The method did not work at the highly acidic pH (when acidified with dilute HCl) but worked well from pH 4.0 to 14.0. The present method was also tested with other tetra-(methyl, ethyl, propyl and n-butyl)ammonium hydroxides. The test chemicals were not converted to their methyl and ethyl esters with tetramethyl and tetraethylammonium hydroxides, whereas they were converted to their corresponding propyl and n-butyl esters with tetrapropyl and tetra(n-butyl)ammonium hydroxides. The method was also applied to two highly cross-linked polymeric sorbents DSC-6S and Oasis HLB. The recovery of the chemicals on these sorbents was observed to be poor. Methylation using phenyltrimethylammonium hydroxide is non-hazardous and advantageous over methylation using diazomethane. The method was applied to the analysis of aqueous samples given in one of the official proficiency tests conducted by the Organization for the Prohibition of Chemical Weapons and all the spiked chemicals were identified as methyl esters. [Copyright &y& Elsevier]

Abstract: The chemical warfare agents (CWA) degrade rapidly in aqueous samples and convert to acidic degradation products. Extraction and identification of the degradation products from complex matrices using simple sample preparation and sensitive detection and identification is the most important step in the off-site analysis of samples. In this present study, we report a simple sample preparation step based on ion-pair (IP) solid-phase extraction (SPE) for the extraction of acidic degradation products of CWA namely methyl, ethyl, propyl phosphonic acids, thiodiglycolic acid and benzilic acid. The analysis was performed on GC–MS in electron impact ionization mode. Three IP reagents triethylamine (TEA), tetrabutylammonium bromide (TBAB) and cetyltrimethyl ammonium bromide (CTAB) were used. The recoveries were estimated using the internal and external standard methods. The recovery of the compounds was almost negligible when TEA was used as IP reagent. The recoveries obtained when TBAB and CTAB were used as IP reagents were high and reproducible. The recovery of test chemicals is above 90%, except for methyl phosphonic acid and ethylphosphonic acid (20.6±3.2% and 35.8±2.5%, respectively). The minimum detection limits of the method were calculated for all chemicals in both full scan and selected ion monitoring modes. The test chemicals could be detected in microgram per litre quantities by the IP–SPE method. [Copyright &y& Elsevier]

• SFE of plastic additives is best achieved in dense CO 2 conditions. • Comparison of extraction methods shows good performance of SFE. • SFE-SFC-MS avoids significant laboratory contaminations. • SFE-SFC-MS reduces analysis time, solvent and consumables. • Transferring a compressible fluid ensures minimal band broadening. Plastic additives are introduced in plastic material formulations, along with organic polymers, to offer different properties such as stability, plasticity or color. However, plastic additives may migrate from the plastic material to the content (in case of plastic containers) or to the material in contact with the plastic, like human skin. In the case of plastic medical devices, this migration is of particular interest, as plastic additives may be deleterious to health. In the present paper, we examined the interest of combining supercritical fluid extraction (SFE) to supercritical fluid chromatography (SFC) hyphenated to mass spectrometry (MS) in an online system to characterize plastic additives in laboratory gloves, taken as samples of medical devices. A set of target compounds comprising 18 plasticizers, 4 antioxidants and 2 lubricants was defined and their detectability with MS was examined, where it appeared that electrospray ionization (ESI) provided better detectability than atmospheric pressure chemical ionization (APCI). After examining possible stationary phases with the help of Derringer desirability function, an isocratic chromatographic method (CO 2 :methanol 95:5) was developed on Shim-pack UC Phenyl column. The extraction method was examined with a 3-level full factorial design of experiments to optimize the extraction temperature (40 °C) and pressure (200 bar). The online SFE-SFC-MS method was compared to offline methods where the samples were extracted with liquid solvents at atmospheric pressure or high pressure then analysed with SFC-MS. In all cases, offline methods showed significant contaminants (like the oleamide lubricant) issuing from laboratory plastic materials as nitrogen drying station, syringes and filters, while the online method allowed a complete elimination of laboratory contaminations. Furthermore, the online method saved time, solvents and laboratory consumables. It will also show that transferring a compressible fluid from a loading loop is favourable to high efficiency, as the resulting chromatographic peaks are much thinner than when transferring a liquid. Compared to injecting liquid heptane, the efficiency increase was 3.4-fold, while compared to injecting liquid methanol (a common practice in SFC), the efficiency increase was 13-fold. Finally, the additive composition of different laboratory gloves was compared. [ABSTRACT FROM AUTHOR]

• A mathematical model based on the plate theory and the Van Deemter equation was built to describe and predict ion chronogram from in-tube-SPME-MS. • An interpretation upon the Van Deemter equation was described to explain band spread during elution process from in-tube SPME device. • Unimodal signal pattern of ion chronogram from in-tube-SPME-MS varies experimentally in a controllable way under adjustment of length of device or elution flow rate. • An optimization framework was presented to explore device designs and experimental parameters to track targeted ion chronograms with "desired" peak shape patterns. A mathematical description and experimental outputs exhibited that an ion chronogram from an in-tube solid-phase microextraction (SPME) device linked with mass spectrometry (in-tube-SPME-MS) generally appears as a right-skew unimodal signal with a heavy right tail. Analogous to liquid chromatography coupled with mass spectrometry (LC-MS), in-tube-SPME-MS can utilize the area under its produced ion chronogram for regression analysis and has been shown to be a potential approach for fast quantification of analyte. Different level of unimodity of signal in the ion chronogram could positively or negatively affect the choice of the area used for quantification and finally impact on analysis sensitivity and time efficiency of in-tube-SPME-MS. In the paper, we showed that different in-tube SPME design choices and elution experimental setups produce ion chronograms with controllable varying unimodal peak shape patterns. An improved mathematical model was built based on the plate theory of chromatography and the Van Deemter equation to quantitatively describe the elution process from in-tube-SPME device. A computer simulation was implemented to predict ion chronograms and the results were compared with experimental ion chronograms to show the effectiveness of the model. An optimization framework was further presented based on the model to identify optimal device designs (length and diameter of device) and experimental parameters (flow rate) to track targeted ion chronograms with "desired" peak shape patterns. Empirical elution experiments with the in-tube SPME devices adopting optimized geometric parameters and optimal experimental setups confirmed the consistency between the experimental ion chronograms and the numerical simulations to a certain level. [ABSTRACT FROM AUTHOR]

Solid-phase microextraction (SPME) coupled to gas chromatography/mass spectrometry (GC/MS) has been applied to the analysis of volatile organic compounds emitted from a naturally aged groundwood pulp paper originating from an old book in order to access the products produced through the decomposition reactions occurring in paper upon ageing. Two different extraction methods were developed and compared: headspace SPME and contact SPME. The influence of few extraction parameters were tested in order to define the best extraction conditions. An optimised non-destructive contact SPME method was elaborated and allowed the characterisation of more than 50 individual constituents. [Copyright &y& Elsevier]

• Migration of chemicals from paper-based food packaging • LC-HRMS non-targeted workflow for data analysis • Improved identification using t R prediction model based on t R /log K ow relationship Potential contamination of food with chemicals migrating from food packaging is an important, yet under-investigated area of food safety. In this study, we examined chemicals migrating from common paper-based food packaging: pizza boxes and pizza box liners, butcher paper and liquid egg containers. Migration tests were conducted with a food simulant for 10 days, and migrated chemicals were identified with liquid chromatography (LC) - high resolution mass spectrometry (HRMS) with mass error < 3 ppm. HRMS identification was based on spectra and/or structure matching against commercial databases (MzCloud, ChemSpider, and Extractable and Leachable high resolution accurate mass (HRAM) database). Following HRMS identification, orthogonal LC retention information was utilized to further refine the data and reduce false positive findings. A model for calculating retention times (t R) based on octanol-water partition coefficient (log K ow) values was evaluated and applied for HRMS data refining. Using this approach, 153 migrated chemicals were identified, of which five were further confirmed with reference analytical standards. Additionally, amounts of bisphenol A and bisphenol S, the chemicals of toxicological concerns, were measured at the levels below the established regulatory limits for migration, indicating no/low risk to consumer's health. This study demonstrated the utility of LC-HRMS for confident identification of food packaging migrants. [ABSTRACT FROM AUTHOR]

• Fabric phase sorptive extraction was applied for enrichment of acrylate compounds • Under the optimized condition satisfactory results were obtained • Thirteen types of recycled polyethylene terephthalate were chosen as real samples • Migration of acrylates to food simulants investigated • Acrylates were found in some samples at ng g−1 levels This article presents fabric phase sorptive extraction (FPSE) as a simple and effective pre-concentration method for the enrichment of acrylate compounds in different food simulants and subsequent analysis of the extracts by ultra-high-performance liquid chromatography with mass spectrometric detection (UPLC-MS). Acrylate compounds come from acrylic adhesives used commonly for sticking the paper labels on polyethylene terephthalate (PET) bottles and therefore, they may exist in recycled polyethylene terephthalate (rPET). Four acrylates were studied: ethylene glycol dimethacrylate (EGDM), pentaerythritol triacrylate (PETA), triethylene glycol diacrylate (TEGDA) and trimethylolpropane triacrylate (TMPTA). Five different types of FPSE media coated with different sol-gel sorbents were studied and finally sol-gel polyethylene glycol- polypropylene glycol-polyethylene glycol triblock copolymer (PEG-PPG-PEG) coated FPSE media was chosen for its satisfactory results. The optimal conditions affecting the extraction efficiency of compounds were determined in three different food simulants. Statistical evaluation of this method reveals good linearity and precision. Under the optimized conditions, the method provided limits of detection of the compounds in the range of (0.1–1.9 ng g−1, 0.1–1.2 ng g−1, 0.2–2.3 ng g−1) in EtOH 10%, HAc 3% and EtOH 20% and the enrichment factor values (EFs) after applying N 2 were in the range of 11.1–25.0, 13.8–26.3, 8.3–21.9, in simulants A, B and C respectively. The optimized method was applied successfully to analyze thirteen types of recycled PET samples. Acrylates were found in some of the samples at ng g−1 levels. [ABSTRACT FROM AUTHOR]

• Inorganic ions are retained in HILIC/ESI-MS and co-elute with organic analytes. • Co-elution causes adduct and cluster formation between inorganic ions and analytes. • Degree of adduct formation is dependent on inorganic ion concentration in the sample. • Quantitative analyte response depend on sample inorganic ion concentration. Hydrophilic interaction liquid chromatography (HILIC)/ electrospray ionisation-mass spectrometry (ESI-MS) has gained interest for the analysis of polar analytes in bioanalytical applications in recent years. However, ESI-MS is prone to adduct formation of analytes. In contrast to reversed phase chromatography, small inorganic ions have retention in HILIC, i.e. analytes and inorganic ions may co-elute, which could influence the adduct formation. In the present paper, it was demonstrated that the co-elution of sodium ions or potassium ions and analytes in HILIC/ESI-MS affect the adduct formation and that different concentrations of sodium ions and potassium ions in biological samples could have an impact on the quantitative response of the respective adducts as well as the quantitative response of the protonated adduct. The co-elution also lead to cluster formation of analytes and sodium formate or potassium formate, causing extremely complicated spectra. In analytical applications using HILIC/ESI-MS where internal standards are rarely used or not properly matched, great care needs to be taken to ensure minimal variation of inorganic ion concentration between samples. Moreover, the use of alkali metal ion adducts as quantitative target ions in relative quantitative applications should be made with caution if proper internal standards are not used. [ABSTRACT FROM AUTHOR]

• ESI-MS/MS fragmentation pattern of the [M+Na]+ ion of PEs was studied. • Fragment ions useful to detect known and new PEs in J. curcas seed oil were found. • Method is useful to detect PEs contamination of derivatives for food use. • Use of MeOH/H 2 O (85:15) in HPLC-ESI-MS/MS analysis enhanced the [M+Na]+ ion signal. Jatropha curcas L. is an inedible plant whose seed oil is an interesting source for biodiesel production. Seed cake, the main byproduct remaining (about 70% w/w) after the oil extraction process, has a high nutritional value but the presence in Jatropha curcas seed of phorbol esters (PEs), a family of toxic compounds with a tigliane skeleton, prevents application of seed cake and other byproducts (e.g. glycerin) in animal feed without an efficient detoxification. Considering the high toxicity of PEs, it is important to have a sensitive analytical method to evaluate the presence of these compounds in Jatropha curcas derivatives. In this paper we present the study of the ESI-MS/MS fragmentation pattern of the [M+Na]+ ion at m / z 733.5 of the six known PEs, namely Jatropha factors (JFs) C 1 -C 6 , which allowed to tentatively identify a series of characteristic and specific fragment ions useful to reveal the presence of JFs in Jatropha curcas seed oil, distinguish them from each other, and identify new PEs (J1-J4). Moreover, the substitution of the usual acetonitrile/water as mobile phase with a mixture of methanol/water (85:15, v/v) allowed to increase the signal of the sodium adduct of about 50-fold during the HPLC-ESI-MS/MS analysis. [ABSTRACT FROM AUTHOR]

Highlights • Matrix effect does not limit the use of CPE coupled to LC–MS/MS. • Low surfactant concentration and high extraction temperature reduce the risk of ME. • Significant absolute ME (<85% or >115%) was observed only for 25% of the analytes. • Molecular descriptors (HDB, ClogP, PSA) help to identify compounds prone to ME. • A new term – the surfactant effect – was introduced. Abstract Matrix effects are one of the most challenging issues in the analysis of complex samples using liquid chromatography coupled to mass spectrometry (LC–MS). Apart from the instrumental origin, these effects are also related to sample preparation. Cloud-point extraction (CPE) is rarely combined with LC–MS as it requires the use of surfactants which might interfere with droplet evaporation. Thus, they are suspected to cause a significant matrix effect (signal suppression). In this paper, 73 model drugs with different physicochemical properties were screened to analyse how susceptible LC-MS is to the absolute and relative matrix effect (ME) when coupled with CPE for measurements in human plasma. Three combinations of the surfactant Triton X-114 concentration (1.5% or 6%) and extraction temperature (40 or 55 °C) in six pH values gave over 1300 analyte-sample preparation condition pairs. A new term – surfactant effect (calculated for the standard solution) – allowed us to distinguish between the surfactant effect and that related to interferences from human plasma. The screening revealed that CPE combined with LC–MS is not related to a significant ME in the optimal pH of extraction. A significant absolute ME (<85% or>115%) was observed only for 25% of the analytes. Data processing (principal component analysis, classification trees, partial least squares-discriminant analysis) based on the extraction conditions and molecular descriptors helped to identify compounds prone to the matrix effect and speed up method development. A low surfactant concentration and low temperature decreased both the absolute and relative ME. pH of the extraction influenced only the relative ME. Low retention time reduced the risk of relative ME, whereas high polarity and the possibility of hydrogen bond formation minimized the occurrence of the surfactant effect and absolute ME. A significant relative ME (>15%) was observed only for 11% of the compounds, thus CPE merged with LC–MS allowed to measure drug concentrations in a reliable manner for majority of compounds. The presented approach may be further applied to other analytes and matrices. [ABSTRACT FROM AUTHOR]

Highlights • scyllo -Inositol and kestoses were found for the first time in cocoa beans by GC–MS. • scyllo -Inositol, 1-kestose and galactinol were selected as target carbohydrates. • HILIC-ESI-TOF MS method was optimized for the analysis of target carbohydrates. • Target LMWC were quantified in cocoa beans from different origin and fermentation status. • Galactinol could be a potential indicator of fermentation status. Abstract The low molecular weight carbohydrate (LMWC) profile of cocoa beans has recently been studied using hydrophilic interaction liquid chromatography coupled to electrospray ionization-time of flight mass spectrometry (HILIC-ESI-TOF MS) and HILIC-ESI-tandem mass spectrometry (HILIC-ESI-MSn). However, different LMWC could not be unambiguously identified. Thus, as a first approach in this paper, gas chromatography coupled to mass spectrometry (GC–MS) was used as a complementary analytical technique to characterize LMWC of cocoa beans. Different mono-, di-, tri- and tetrasaccharides, as well as myo -inositol, galactinol and a diglycosil glycerol were detected. scyllo -Inositol, 1-kestose and 6-kestose were identified in unfermented cocoa beans for the first time. Moreover, other minor LMWC were tentatively assigned as fructosyl-fructose, fructosyl-glucose and glucosyl-sucrose. As a second step, in order to evaluate new possible indicators of cocoa bean origin or fermentation status, scyllo -inositol, 1-kestose and galactinol were selected as target compounds and a HILIC-ESI-TOF MS method was optimized for their analysis. The optimized conditions, using an acetonitrile:water gradient with 0.05% ammonium hydroxide at 40 °C showed narrow peaks (w h : 0.3-0.5 min) with good resolution values (R s : 0.83–2.83). The validated HILIC-ESI-TOF MS method was applied to the analysis of 35 cocoa bean samples from different origins and fermentation status. The content of scyllo -inositol, 1-kestose and galactinol in unfermented beans (n = 21) was in the range of traces-504.9, 36.1–133.5 and traces-1970.4 μg g−1 cocoa DM respectively. In fermented beans (n = 14), the content of scyllo -inositol and 1-kestose was in the range of 15.5–491.9 and traces-115.5 μg g−1 cocoa DM respectively. Galactinol was absent in fermented beans, indicating that it could be a potential indicator of fermentation status. The methodology proposed could be used for quality control of natural products and other food ingredients containing inositols and oligosaccharides. [ABSTRACT FROM AUTHOR]

Abstract: Sorbent tubes/traps are widely used in combination with gas chromatographic (GC) analytical methods to monitor the vapour-phase fraction of organic compounds in air. Applications range from atmospheric research and ambient air monitoring (indoor and outdoor) to occupational hygiene (personal exposure assessment) and measuring chemical emission levels. Part 1 of this paper reviewed the main sorbent-based air sampling strategies including active (pumped) tube monitoring, diffusive (passive) sampling onto sorbent tubes/cartridges plus sorbent trapping/focusing of whole air samples that are either collected in containers (such as canisters or bags) or monitored online. Options for subsequent extraction and transfer to GC(MS) analysis were also summarised and the trend to thermal desorption (TD)-based methods and away from solvent extraction was explained. As a result of this trend, demand for TD-compatible sorbents (alternatives to traditional charcoal) is growing. Part 2 of this paper therefore continues with a summary of TD-compatible sorbents, their respective advantages and limitations and considerations for sorbent selection. Other analytical considerations for optimizing sorbent-based air monitoring methods are also discussed together with recent technical developments and sampling accessories which have extended the application range of sorbent trapping technology generally. [Copyright &y& Elsevier]

Abstract: In the pharmaceutical industry the growing number of samples to be analyzed requires high throughput and fully automated analytical techniques. Commonly used sample-preparation methods are solid-phase extraction (SPE), liquid–liquid extraction (LLE) and protein precipitation. In this paper we will discus a new sample-preparation technique based on SPE for high throughput drug extraction developed and used by our group. This new sample-preparation method is based on monolithic methacrylate polymer as packing sorbent for 96-tip robotic device. Using this device a 96-well plate could be handled in 2–4min. The key aspect of the monolithic phase is that monolithic material can offer both good binding capacity and low back-pressure properties compared to e.g. silica phases. The present paper presents the successful application of monolithic 96-tips and LC–MS/MS by the sample preparation of busulphan, rescovitine, metoprolol, pindolol and local anaesthetics from human plasma samples and cyklophosphamid from mice blood samples. [Copyright &y& Elsevier]

Abstract: An improved process of Soxhlet extraction assisted by microwave, called microwave-integrated Soxhlet (MIS) is proposed for the extraction of oils and fats from different food matrixes such as oleaginous seeds, meat and bakery products. Optimal conditions for extraction were obtained using a response surface methodology and reached from a central composite design allowing us to conclude in a previous paper that the proposed process ensures complete, efficient and accurate extraction for lipids determination from olives. In this paper, the peak areas of the main fatty acids extracted with MIS from olive seeds were considered as response variables and submitted to an analysis of variance in order to determine if there was a significant link between the extraction of fatty acids and the variables required in extraction procedures. Results have shown that MIS parameters do not affect the composition of the extracts. For the generalization of the study with several food matrixes, MIS extraction results obtained were then compared to conventional Soxhlet extraction in terms of crude extract and fatty acid composition and shown that the oils extracted by MIS were quantitatively and qualitatively similar to those obtained by conventional Soxhlet extraction. MIS labstation can be considered as a new and general alternative for the extraction of lipids by using microwave energy. [Copyright &y& Elsevier]

Abstract: Hyphenated techniques such as capillary electrophoresis–mass spectrometry (CE–MS) or high-performance liquid chromatography with diode array detection (HPLC–DAD), etc., are known to produce a huge amount of data since each sample is characterized by a two-way data table. In this paper different ways of obtaining sample-related information from a set of such tables are discussed. Working with original data requires alignment techniques due to time shifts caused by unavoidable variations in separation conditions. Other pre-processing techniques have been suggested to facilitate comparison among samples without prior peak alignment, for example, ‘binning’ and/or ‘blurring’ the data along the time dimension. All these techniques, however, require optimization of some parameters, and in this paper an alternative parameter-free method is proposed. The individual data tables (X) are represented as Gram matrices (XX T), where the summation is taken over the time dimension. Hence the possible variations in time scale are eliminated, while the time information is at least partly preserved by the correlation structure between the detection channels. For comparison among samples, a similarity matrix is constructed and explored by principal component analysis and hierarchical clustering. The Gram matrix approach was tested and compared to some other methods using ‘binned’ and ‘blurred’ data for a data set with CE–MS runs on urine samples. In addition to data exploration by principal component analysis and hierarchical clustering, a discriminant partial least squares model was constructed to discriminate between the samples that were taken with and without the prior intake of a drug. The result showed that the proposed method is at least as good as the others with respect to cluster identification and class prediction. A distinct advantage is that there is no need for parameter optimization, while a potential drawback is the large size of the Gram matrices for data with high mass resolution. [Copyright &y& Elsevier]

Abstract: A simple and sensitive method for the determination of abietic acid and dehydroabietic acid in food samples was developed using a fully automated method consisting of in-tube solid-phase microextraction (SPME) coupled with liquid chromatography–mass spectrometry (LC/MS). These compounds were separated within 5min by HPLC using an ODS-3 column and 5mM ammonium formate/acetonitrile (10/90, v/v). Electrospray ionization conditions in the negative ion mode were optimized for MS detection of abietic acid and dehydroabietic acid. The optimum in-tube SPME conditions were 20draw/eject cycles of 40μL of sample using a Supel Q PLOT capillary column as an extraction device. The extracted compounds were easily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. Using the in-tube SPME LC/MS method, good linearity of the calibration curve (r >0.9998) was obtained in the concentration range from 0 to 50ng/mL, and the detection limits (S/N=3) of abietic acid and dehydroabietic acid were 2.9 and 2.1pg/mL, respectively. The in-tube SPME method showed above 75-fold greater sensitivity than the direct injection method (5μL injection). This method was applied successfully to analysis of food samples without interference peaks. The recoveries of abietic acid and dehydroabietic acid spiked into liquid samples were above 79%, and the relative standard deviations were below 6.6%. These compounds were detected at ng/mL or ng/g levels in various liquid or solid food samples contacted with paper. [Copyright &y& Elsevier]

Abstract: Chlortetracycline (CTC) is a member of the group of the tetracycline antibiotics used in human and veterinary medicine. Its reliable measurement in edible tissues is hampered by the fact that CTC is subjected to keto-enol tautomerism resulting in its keto- and enol-form. Also, it undergoes epimerization to form its 4-epimer. In this paper, we present an LC–electrospray ionization (ESI)–MS/MS method to analyze the CTC content in pig tissues, with the originality that it apports a solution to overcome the possible interference on the measurement of the keto-enol tautomerism equilibrium, which is influenced by several factors. Therefore, the minced tissue samples were incubated at 56°C, forcing the equilibrium in favour of the CTC keto-form. The CTC keto-tautomer, as a measure of the total CTC content, was then quantified by LC–ESI–MS/MS, after further extraction of the tissue samples, consisting of a liquid extraction with sodium succinate solution (pH 4.0), followed by protein removal with trichloroacetic acid and paper filtration, and finally solid-phase clean-up on an hydrophilic-lipophilic balance (HLB) polymeric reversed-phase column. The method could be validated for pig muscle, liver and kidney tissues – for which maximum residue limits (MRLs) have been fixed by the European Union – with respect to linearity, trueness and precision, in accordance with the European guidelines. [Copyright &y& Elsevier]

Abstract: Ion-pairing high performance liquid chromatography (IP-HPLC) was utilized to monitor the composition changes of blue gel pen ink entries on paper stored in different light conditions and natural environment. The chromatographic conditions were optimized by comparing the separation efficiencies of the blue gel pen inks using a series of ion-pairing reagents, including ammonium carbonate, ammonium acetate, triethylamine acetate, tributylamine acetate, tetrabutylammonium bromide and dihexylammonium acetate. It has been found that tributylamine acetate was a suitable ion-pairing reagent for separation of the inks on the common C18 column. The analysis results of the ink entries on paper in different aging conditions showed that the tendency of composition change in natural aging condition was similar with those in fluorescent light and UV light conditions, respectively. One main component dye of the blue gel pen ink, Acid Blue 9, and its degradation products were identified by ion-pairing high performance liquid chromatography coupled with electrospray tandem mass spectrometry. The results showed that the main degradation products originated from the Acid Blue 9. It gave a reasonable explanation for the changing rules of the relative content of the dyes in the blue gel pen ink. The results obtained can provide scientific evidences for dating of the blue gel pen ink entries on documents. [Copyright &y& Elsevier]

Abstract: Paper cellulose has been hydrolyzed with calcium alginate immobilized cellulase to produce carbohydrate products and the three trace sugars, galactose, arabinose, and mannose in the cellulase hydrolysate have been analyzed by HPIEC/ESI-MS. Applying the on-line cut-off technique to the HPIEC/ESI-MS can cut the high concentration glucose off to eliminate its interference on the peaks of minor sugars and enhance their signals from 1.1- to 1.6-fold. However, the on-line post column addition of 15% ethanol to the eluate can increase the signal of the three trace sugars, galactose, arabinose, and mannose up to 17-, 23-, and 11-fold, respectively, and make the corresponding detection limits as 0.04, 0.04, and 0.03ppm. The accuracies of the quantitative analysis for the three trace sugars with the signal enhanced HPIEC/ESI-MS by the two enhancement methods were larger than 95%. The precisions of the analytical results were also greatly improved by the assistance of the two techniques and were less than 6.5%. The quantitative analysis of the three trace sugars was performed with the internal standard method and the internal standard (IS) was sorbitol. Overall, the signal enhancement of HPIEC/ESI-MS and quantification of the three trace sugars by the on-line cut-off technique and organic modifier addition was successful. [Copyright &y& Elsevier]

Abstract: The potential of solid-phase extraction coupled on-line to liquid chromatography/electrospray tandem mass spectrometry (SPE-LC–ESI-MS/MS) has been investigated in this paper for the efficient sensitive quantification and confirmation of 16 antibiotics in water. The list of targeted analytes included 10 quinolones (oxolinic acid (OXO), nalidixic acid (NAL), flumequine (FLU), marbofloxacine (MAR), ofloxacine (OFLO), enrofloxacine (ENR), pefloxacine (PEF), ciprofloxacine (CIP), pipemidic acid (PIPE), norfloxacine (NOR)) and 6 penicillins (penicillin G (PEN), oxacillin (OXA), dicloxacillin (DIC), piperacillin (PIP), cloxacillin (CLO) and ampicillin (AMP)) that were determined in ground and surface water. The procedure is based on the injection of 9.8mL of sample into the SPE-LC–MS/MS system and the measurement of antibiotics by selected reaction monitoring mode, using a triple quadrupole analyser. The method has been validated at realistic low concentrations that might be present in environmental water, i.e. 10 and 100ngL−1, obtaining recoveries between 74% and 123% with relative standard deviation lower than 14%. Matrix effects were not relevant in most of cases, except for ampicillin in surface water, where notable signal suppression was observed. The limits of detection were as low as 0.4–4.3ngL−1. The method developed allows the rapid screening and quantification of all the analytes selected by acquiring one MS/MS transition (normally the most sensitive) for each compound. It was applied to a number of actual surface and groundwater samples with several compounds being detected, mainly quinolones, at low ngL−1 levels. Special attention was given to the confirmation of compounds detected in water due to the difficulties of obtaining confident confirmation at low ngL−1. This matter has been of growing concern in the last few years as reflected by recent papers and correspondence. The acquisition of several MS/MS transitions for each compound detected in a second independent analysis allowed the unequivocal confirmation of identity, avoiding reporting false-positives. Finally, the potential of QTOF instruments to confirm positive samples has also been evaluated and compared with triple quadrupole analysers. [Copyright &y& Elsevier]

Abstract: The versatility of non-aqueous capillary electrophoresis (NACE) results mainly from the variety of physico-chemical properties of the different solvents. They provide solubility for a wide range of analytes, enable to control electrophoretic selectivity, but affect in some cases UV absorbance detection. The coupling of NACE to electrospray mass spectrometry (ESI-MS) allows to cope with the high UV cut-off of some CE relevant solvents (e.g., formamides). In this paper the pure organic solvents methanol, acetonitrile, dimethylsulfoxide, formamide, N-methylformamide and N,N-dimethylformamide are evaluated against water for the preparation of ammonium acetate electrolytes to separate the basic model substances 2-aminobenzimidazole, procaine, propranolol and quinine with NACE–MS. MS coupling is assisted with the sheath liquid water–isopropanol (1:4, v/v) with 0.1% formic acid. The goal of the paper is to assess the influence of the solvent on selectivity, separation speed, and peak efficiency for a given set of model compounds on a simple empirical basis. It should give the user an idea how the separation quality is changed when nothing but the running solvent is altered. The obtained efficiency results were discussed with respect to physico-chemical models described in literature (assuming longitudinal diffusion as the only source of band broadening), but no satisfying correlations with solvent properties could be traced. The feasibility of all six organic solvents for MS coupling was demonstrated and the influence of the separation solvent on the MS detection performance was compared. In the seven different solvents, the shortest run time was obtained with acetonitrile, the best peak resolution with the amphiprotic solvents (especially methanol) best peak efficiency with methanol and formamide, and the most sensitive ESI-MS detection with acetonitrile and methanol, but with only slight advantage to water. [Copyright &y& Elsevier]

Manganese is a trace element known to activate many enzymes involved in metabolic processes and it shows protective function against oxidative stress. On the other hand, increased Mn levels are known for damaging the central nervous system, resulting in motoric abnormalities and psychic disorder. Such additional Mn exposure can cause an “Mn overflow” in the liver, accompanied by production of specific (labile) Mn transporters (Mn-species). The speciation of these Mn-compounds is still unknown but they are believed targeting the brain. The aim of this paper was to develop a speciation method for manganese species in liver extracts, which allows to speciate the compounds quickly and with minimal risk of species alteration. Capillary electrophoresis (CE)–inductively coupled plasma mass spectrometry (ICP-MS) offers a valuable tool as analytes are not in contact to a stationary phase which probably affects species stability. Separation usually is fast and ICP-MS detection is element specific and sensitive. The paper describes the set-up and optimization of the hyphenated technique, optimization of separation according to pH and finally the Mn speciation of a liver extract. Several Mn species were found, such as arginase, Mn-transferrine, Mn-albumine and some more. The detection limit of the method was determined at 1.1 μg Mn/L independent on the species. [Copyright &y& Elsevier]

This paper reports the development of a highly selective and sensitive method for the determination of parts-per-billion level of 1,3-dichloropropan-2-ol (1,3-DCP) and 3-chloropropane-1,2-diol (3-MCPD) in soy sauce using capillary gas chromatography with mass spectrometric detection. Samples were homogenised, mixed with sodium chloride solution and then adsorbed on silica gel. The loaded silica gel was packed into a chromatographic column, from which chloropropanols were extracted by elution with ethyl acetate. Heptafluorobutyric acid anhydride was added to the concentrated eluant to derivatise the chloropropanols and the derivatised analytes were separated by gas chromatography, identified and quantified by mass spectrometry. A linear relationship between the concentration of the two chloropropanols and the detector response was obtained over the concentration range of 10–1000 μg/kg. Precision of the method was satisfactory at about 5%, and recoveries of 1,3-DCP and 3-MCPD from soy sauce samples spiked at 25 μg/kg were 77 and 98%, respectively. The limit of quantitation of the method was found to be about 5 μg/kg for 1,3-DCP and 3-MCPD, respectively meeting the requirements of tolerance limits adopted by different international institutions and governments around the world. This paper is the first of its kind in reporting an analytical procedure for the simultaneous separation and determination of 3-MCPD and 1,3-DCP, a more potent contaminant, at low μg/kg level. [Copyright &y& Elsevier]

Highlights • This method has a low detection limit and an excellent linear correlation. • It is not affected by the chemical properties of the organic solvents. • This method is very environmentally friendly and saves reagents. Abstract This paper describes the development of a novel gas chromatography-mass spectrometry-selected ion monitoring (GC/MS-SIM) method for the determination of trace water contents of organic solvents, using the characteristic m/z 18, m/z 17, and m/z 16 ions of H 2 O as the qualitative ion and the m/z 18 ion as the quantifier ion. The accuracy and precision of this method were validated. An excellent linear correlation was obtained for trace water contents between 0 and 0.5217 wt%, with a correlation coefficient (R 2) of 0.9999, in addition to spike recoveries of 82.6–112.6%, and relative standard deviations (n = 6) of 0.4–7.2%. The limit of detection (S/N = 3) and limit of quantitation (S/N = 10) for the trace water contents of organic solvents were 0.0005% wt% and 0.0016% wt%, respectively.The analytical results confirmed that this method was useful for determining the trace water contents of organic solvents, because it has a low detection limit and wide linear range. It requires only small amounts of the samples and enables sample batch analysis. It is very environmentally friendly and saves reagents. [ABSTRACT FROM AUTHOR]

Chromatographic systems coupled with mass spectrometry detection are widely used in biological studies investigating how levels of biomolecules respond to different internal and external stimuli. Such changes are normally expected to be of low magnitude and therefore all experimental factors that can influence the analysis need to be understood and minimized. Run order effect is commonly observed and constitutes a major challenge in chromatography-mass spectrometry based profiling studies that needs to be addressed before the biological evaluation of measured data is made. So far there is no established consensus, metric or method that quickly estimates the size of this effect. In this paper we demonstrate how orthogonal projections to latent structures (OPLS®) can be used for objective quantification of the run order effect in profiling studies. The quantification metric is expressed as the amount of variation in the experimental data that is correlated to the run order. One of the primary advantages with this approach is that it provides a fast way of quantifying run-order effect for all detected features, not only internal standards. Results obtained from quantification of run order effect as provided by the OPLS can be used in the evaluation of data normalization, support the optimization of analytical protocols and identification of compounds highly influenced by instrumental drift. The application of OPLS for quantification of run order is demonstrated on experimental data from plasma profiling performed on three analytical platforms: GCMS metabolomics, LCMS metabolomics and LCMS lipidomics. [ABSTRACT FROM AUTHOR]

The peak shifts may lead to an incorrect statistical result for nontargeted metabolomics profiling, such as classification and discrimination in pattern recognition. In the paper, a more accurate alignment algorithm is developed based on Subwindow Factor Analysis and Mass Spectral information (SFA-MS). Compared with other methods, this new algorithm aligns the peaks more accurately without changing their shapes, especially for the overlapping peak clusters. To begin, the Continuous Wavelet Transform with Haar wavelet as the mother wavelet (Haar CWT) is used to determine the position and width of peaks. On this basis, the candidate drift points are confirmed by Fast Fourier Transform (FFT) cross correlation. Furthermore, the MS fitting degree of the common components between the reference chromatogram and the raw chromatogram is determined by the Subwindow Factor Analysis (SFA). When the MS information between reference and raw peaks is identical, the corresponding moving points are the optimum shifts. It is remarkable that all the peaks are moved through linear interpolation in the non-peak parts, so that the aligned chromatograms remain unchanged. The SFA-MS algorithm was implemented in the Matlab language and is available as an open source package. [ABSTRACT FROM AUTHOR]

With mass spectrometric detection in liquid chromatography, co-eluting impurities affect the analyte response due to ion suppression/enhancement. Internal standard calibration method, using co-eluting stable isotope labelled analogue of each analyte as the internal standard, is the most appropriate technique available to correct for these matrix effects. However, this technique is not without drawbacks, proved to be expensive because separate internal standard for each analyte is required, and the labelled compounds are expensive or require synthesising. Traditionally, standard addition method has been used to overcome the matrix effects in atomic spectroscopy and was a well-established method. This paper proposes the same for mass spectrometric detection, and demonstrates that the results are comparable to those with the internal standard method using labelled analogues, for vitamin D assay. As conventional standard addition procedure does not address procedural errors, we propose the inclusion of an additional internal standard (not co-eluting). Recoveries determined on human serum samples show that the proposed method of standard addition yields more accurate results than the internal standardisation using stable isotope labelled analogues. The precision of the proposed method of standard addition is superior to the conventional standard addition method. [ABSTRACT FROM AUTHOR]

Methylstenbolone (2,17α-dimethyl-5α-androst-1-en-17β-ol-3-one) is a synthetic anabolic and androgenic steroid (AAS) sold as an oral ‘nutritional supplement’ under the brand names ‘Ultradrol’, ‘M-Sten’ and ‘Methyl-Sten’. Like other AASs, methylstenbolone is a prohibited substance in both human and equine sports. This paper describes the studies of the in vitro and in vivo metabolism of methylstenbolone in horses using LC/HRMS, GC/MS and GC/MS/MS. Phase I in vitro metabolic study of methylstenbolone was performed using homogenised horse liver. Hydroxylation was the only biotransformation observed. Six in vitro metabolites were detected including four mono-hydroxylated metabolites, namely 16α/β-hydroxymethylstenbolone (M1a, M1b), 20-hydroxymethylstenbolone (M1c), 6-hydroxymethylstenbolone (M1d), and two dihydroxylated methylstenbolone metabolites (M2c–M2d). An in vivo experiment was carried out using two retired thoroughbred geldings. Each horse was administered with 100 mg methylstenbolone supplement by stomach tubing daily for three consecutive days. Methylstenbolone and 14 metabolites were detected in the post-administration urine samples. The proposed in vivo metabolites included 16α/β-hydroxymethylstenbolone (M1a, M1b), 20-hydroxymethylstenbolone (M1c), two dihydroxylated methylstenbolone (M2a, M2b), 17- epi -methylstenbolone (M3), methasterone (M4), 2,17-dimethylandrostane-16,17-diol-3-one (M5), dihydroxylated and reduced methylstenbolone (M6), 2α,17α-dimethylandrostane-3α,17β-diol (M7), 2,17-dimethylandrostane-3,16,17-triol (M8a–M8c) and 2,17-dimethylandrostane-2,3,16,17-tetraol (M9), formed from hydroxylation, reduction and epimerisation. Methylstenbolone and ten of its metabolites could be detected in post-administration plasma samples. The highest concentration of methylstenbolone detected in urine was about 10–36 ng/mL at 3–4 h after the last administration, while the maximum concentration in plasma was about 0.4–0.7 ng/mL at 1 h after the last administration. For controlling the misuse of methylstenbolone, M8c and M9 gave the longest detection time in urine, while M4, M5 and M6 were the longest detecting analytes in plasma. They could be detected for up to 5 and 4.5 days respectively in urine and plasma. Apart from 16α/β-hydroxymethylstenbolone (M1a, M1b), the methylstenbolone metabolites reported herein have never been reported before. [ABSTRACT FROM AUTHOR]

• A mixed-mode cationic exchange planar sorptive phase is presented. • The sorptive phase is affordable and simple. • It has been used for the isolation of two opioids from saliva samples. • The extraction procedure permits to process of several samples simultaneously. • The use of DI-MS provides a high sample throughput. This article describes the synthesis of mixed-mode cationic exchange (MCX) tapes as sorptive phases in bioanalysis, and it faces the determination of methadone and tramadol in saliva as the model analytical problem. The tapes are synthesized using aluminum foil as substrate, which is subsequently covered with double-sided adhesive tape where the MCX particles (ca. 1.4 ± 0.2 mg) finally adhere. MCX particles allow the extraction of the analytes at the physiological pH, where both drugs are positively charged, minimizing the potential co-extraction of endogenous matrix compounds. The extraction conditions were studied considering the main variables (e.g. ionic strength, extraction time, sample dilution). Under the optimum conditions and using direct infusion mass spectrometry as the instrumental technique, detection limits as low as 3.3 μg·L−1 were obtained. The precision calculated at three different levels, and expressed as relative standard deviation, was better than 3.8%. The accuracy, expressed as relative recoveries, ranged from 83 to 113%. The method was finally applied to determine tramadol in saliva samples from patients under medical treatment. This approach opens the door to easily preparing sorptive tapes based on commercial (or ad-hoc synthesized) sorbent particles. [ABSTRACT FROM AUTHOR]

Detection of illicit drugs in the environmental samples has been challenged as the consumption increases globally. Current review examines the recent developments and applications of sample preparation techniques for illicit drugs in solid, liquid, and gas samples. For solid samples, traditional sample preparation methods such as liquid-phase extraction, solid-phase extraction, and the ones with external energy including microwave-assisted, ultrasonic-assisted, and pressurized liquid extraction were commonly used. The sample preparation methods mainly applied for liquid samples were microextraction techniques including solid-phase microextraction, microextraction by packed sorbent, dispersive solid-phase extraction, dispersive liquid-liquid microextraction, hollow fiber-based liquid-phase microextraction, and so on. Capillary microextraction of volatiles and airborne particulate sampling were primarily utilized to extract illicit drugs from gas samples. Besides, the paper introduced recently developed instrumental techniques applied to detect illicit drugs. Liquid chromatograph mass spectrometry and gas chromatograph mass spectrometry were the most widely used methods for illicit drugs samples. In addition, the development of ambient mass spectrometry techniques, such as desorption electrospray ionization mass spectrometry and paper spray mass spectrometry, created potential for rapid in-situ analysis. [ABSTRACT FROM AUTHOR]

• Recent advances in microsampling techniques for TDM are illustrated. • Classification of microsampling is based on type of biological matrices used. • Advantages and shortcomings of each microsampling technique are discussed • Latest applications of established miniaturized sampling techniques are presented. Conventional sampling of biological fluids often involves a bulk quantity of samples that are tedious to collect, deliver and process. Miniaturized sampling approaches have emerged as promising tools for sample collection due to numerous advantages such as minute sample size, patient friendliness and ease of shipment. This article reviews the applications and advances of microsampling techniques in therapeutic drug monitoring (TDM), covering the period January 2015 – August 2020. As whole blood is the gold standard sampling matrix for TDM, this article comprehensively highlights the most historical microsampling technique, the dried blood spot (DBS), and its development. Advanced developments of DBS, ranging from various automation DBS, paper spray mass spectrometry (PS-MS), 3D dried blood spheroids and volumetric absorptive paper disc (VAPD) and mini-disc (VAPDmini) are discussed. The volumetric absorptive microsampling (VAMS) approach, which overcomes the hematocrit effect associated with the DBS sample, has been employed in recent TDM. The sample collection and sample preparation details in DBS and VAMS are outlined and summarized. This review also delineates the involvement of other biological fluids (plasma, urine, breast milk and saliva) and their miniaturized dried matrix forms in TDM. Specific features and challenges of each microsampling technique are identified and comparison studies are reviewed. [ABSTRACT FROM AUTHOR]

Volatile aldehydes appear in canned vegetables as constituents and some of them can also be present as disinfection by-products (DBPs) because of the contact between vegetables and treated water. This paper describes two static headspace–gas chromatography–mass spectrometry (SHS–GC–MS) methods to determine 15 aldehydes in both the solid and the liquid phases of canned vegetables. The treatment for both phases of samples was carried out simultaneously into an SHS unit, including the leaching of the aldehydes (from the vegetable), their derivatization and volatilization of the oximes formed. Detection limits were obtained within the range of 15–400 μg/kg and 3–40 μg/L for aldehydes in the solid and the liquid phases of the food, respectively. The relative standard deviation was lower than 7% −for the whole array of the target analytes–, the trueness evaluated by recovery experiments provided %recoveries between 89 and 99% and short- and long-term stability studies indicated there was no significant variation in relative peak areas of all aldehydes in both phases of canned vegetables after their storing at 4 °C for two weeks. The study of the origin of the 15 aldehydes detected between both phases of canned vegetables showed that: i) the presence of 13 aldehydes −at average concentrations of 2.2–39 μg/kg and 0.25–71 μg/L for the solid and the liquid phases, respectively– is because they are natural constituents of vegetables; and ii) the presence of glyoxal and methylglyoxal −which are mainly found in the liquid phase (average values, 1.4–4.1 μg/L)– is ascribed to the use of treated water, thereby being DBPs. [ABSTRACT FROM AUTHOR]

The paper presents a new method for the determination of 15 carboxylic acids in samples of postoxidative effluents from the production of petroleum bitumens using ion-pair dispersive liquid-liquid microextraction and gas chromatography coupled to mass spectrometry with injection port derivatization. Several parameters related to the extraction and derivatization efficiency were optimized. Under optimized experimental conditions, the obtained limit of detection and quantification ranged from 0.0069 to 1.12 μg/mL and 0.014 to 2.24 μg/mL, respectively. The precision (RSD ranged 1.29–6.42%) and recovery (69.43–125.79%) were satisfactory. Nine carboxylic acids at concentrations ranging from 0.10 μg/mL to 15.06 μg/mL were determined in the raw wastewater and in samples of effluents treated by various oxidation methods. The studies revealed a substantial increase of concentration of benzoic acids, in samples of wastewater after treatment, which confirms the need of carboxylic acids monitoring during industrial effluent treatment processes. [ABSTRACT FROM AUTHOR]

The present paper is focused on the use of a vacuum ultraviolet absorption spectrometer (VUV) for gas chromatography (GC), within the context of flow modulated comprehensive two-dimensional gas chromatography (FM GC × GC). The features of the VUV detector were evaluated through the analysis of petrochemical and fatty acids samples. Besides responding in a predictable fashion via Beer’s law principles, the detector provides additional spectroscopic information for qualitative analysis. Virtually all chemical species absorb and have unique gas phase absorption features in the 120–240 nm wavelength range monitored. The VUV detector can acquire up to 90 full range absorption spectra per second, allowing its coupling with comprehensive two-dimensional gas chromatography. This recent form of detection can address specific limitations related to mass spectrometry ( e.g., identification of isobaric and isomeric species with very similar mass spectra or labile chemical compounds), and it is also able to deconvolute co-eluting peaks. Moreover, it is possible to exploit a pseudo-absolute quantitation of analytes based on pre-recorded absorption cross-sections for target analytes, without the need for traditional calibration. Using this and the other features of the detector, particular attention was devoted to the suitability of the FM GC × GC-VUV system toward qualitative and quantitative analysis of bio-diesel fuel and different kinds of fatty acids. Satisfactory results were obtained in terms of tailing factor (1.1), asymmetry factor (1.1), and similarity (average value 97%), for the FAMEs mixtures analysis. [ABSTRACT FROM AUTHOR]

Anabolic and androgenic steroids (AASs) are a class of prohibited substances banned in horseracing at all times. The common approach for controlling the misuse of AASs in equine sports is by detecting the presence of AASs and/or their metabolites in urine and blood samples using gas chromatography-mass spectrometry (GC–MS) and liquid chromatography-mass spectrometry (LC–MS). This approach, however, often falls short as the duration of effect for many AASs are longer than their detection time in both urine and blood. As a result, there is a high risk that such AASs could escape detection in their official race-day samples although they may have been used during the long period of training. Hair analysis, on the other hand, can afford significantly longer detection windows. In addition, the identification of synthetic ester derivatives of AASs in hair, particularly for the endogenous ones, can provide unequivocal proof of their exogenous origin. This paper describes the development of a sensitive method (at sub to low parts-per-billion or ppb levels) for detecting 48 AASs and/or their esters in horse hair using ultra-high performance liquid chromatography–high resolution mass spectrometry (UHPLC–HRMS). Decontaminated horse hair was pulverised and subjected to in-situ liquid–liquid extraction in a mixture of hexane − ethyl acetate (7:3, v / v ) and phosphate buffer (0.1 M, pH 9.5), followed by additional clean-up using mixed-mode solid-phase extraction. The final extract was analysed using UHPLC–HRMS in the positive electrospray ionisation (ESI) mode with both full scan and parallel reaction monitoring (PRM). This method was validated for qualitative identification purposes. Validation data, including method specificity, method sensitivity, extraction recovery, method precision and matrix effect are presented. Method applicability was demonstrated by the successful detection and confirmation of testosterone propionate in a referee hair sample. To our knowledge, this was the first report of a comprehensive screening method for detecting as many as 48 AASs and/or their esters in horse hair. Moreover, retrospective analysis of non-targeted AASs and/or their esters was made feasible by re-examining the full scan UHPLC–HRMS data acquired. [ABSTRACT FROM AUTHOR]

• In this study, we addressed a topical issue "A reliable HPLC-ICP-MS method for determining selenoamino acids, especially Selenocysteine (Sec)" after optimizations of proteolysis conditions, chromatographic conditions and determination conditions. The innovation and breakthrough of our research are reflected as the following aspects:. • The physiological health function of selenium is realized through selenoprotein composed of selenocysteine (SeCys) mostly[1], so we planned to detect whether the selenoproteins expressed by lactic acid bacteria have this active selenoamino acid. And it was finally realized through rigorous experimental design and certification. • Compared to the studies in Table 1, our method can successfully detect SeCys, SeCys2, SeMeCys and SeMet simultaneously within 10 min, especially to separate SeCys from SeCys2 after optimization of operation conditions for HPLC-ICP-MS and chromatographic conditions (see Table S1 and S2); And the reagents used in our study are milder and can only be extracted with water and enzyme. • Although SeCys is reductive and can be oxidized, it could be detected from Se-enriched yeast[2, 3]. However, the derivatization method used in those studies is more time-consuming and cumbersome, since the reduction with DTT and other reducing reagents and the derivatization with IAM reagents are easy to produce by-products, which needs extra operation steps to eliminate their effects[2]. So the method developed here is more dominant and can be easily conducted. • In contrast to other molecular identification methods, especially the popular NMR and ESI-MS/MS, HPLC-ICP-MS is more suitable for identifying amino acids containing selenium (see Table 1). Being of the same class of mass spectrometry technique as ESI-MS/MS, HPLC-ICP-MS can more directly separate and identify qualitatively and quantitatively selenoamino acid mixtures through external standard method, and give more intuitive results. NMR is widely used as a "Gold Standard" method to determine the structure of molecular substance, but usually only single pure compound. In our study, we used the commercially available NMR-confirmed standard selenium amino acids to establish and verified the HPLC-ICP-MS method. • The results also indirectly indicated the random incorporation of selenium into LlGPx. This work throws new light on the identification and biosynthesis of organic selenium species in selenoproteins and selenium-riched organisms. • All in all, we believe this paper is suitable for "Journal of Chromatography A". • [1] D.E. Fomenko, W. Xing, B.M. Adair, D.J. Thomas, V.N. Gladyshev, High-throughput identification of catalytic redox-active cysteine residues, Science 315 (2007) 387-389. doi: 10.1126/science.1133114. • [2] K. Bierla, J. Bianga, L. Ouerdane, J. Szpunar, A. Yiannikouris, R. Lobinski, A comparative study of the Se/S substitution in methionine and cysteine in Se-enriched yeast using an inductively coupled plasma mass spectrometry (ICP MS)-assisted proteomics approach, Journal of proteomics 87 (2013) 26-39. • [3] K. Bierla, R. Lobinski, J. Szpunar, Determination of proteinaceous selenocysteine in selenized yeast, International Journal of Molecular Sciences 19 (2018) 543. doi: 10.3390/ijms19020543. A reliable method for simultaneous determination of four organic selenium species by HPLC-ICP-MS was developed and implemented in determining organic selenoamino acids (Se-AAs) in selenoproteins from Lactococcus lactis (L. lactis) NZ9000. The method consisted of liberating Se-AAs from selenoproteins using ultrasound-assisted protease hydrolysis, and quantitatively detecting Se-AA speciations by HPLC-ICP-MS. After optimizations of proteolysis conditions, chromatographic conditions and determination conditions, the established method could efficiently separate the four Se-AAs, including SeCys, SeCys2, SeMeCys and SeMet within 10 min. It presented high sensitivity with the limits of detection and quantitation in the range of 0.197∼0.240 μg∙L−1 and 0.788∼0.960 μg∙L−1, respectively, good repeatability with a relative standard deviation (RSD) of less than 5%, and good recovery in the desired floating range of 90%∼105%, verifying the good accuracy. The method successfully detected four selenium species in the purified glutathione peroxidase (LlGPx) overexpressed in L. lactis NZ9000, SeCys (0.9716∼1.6784 μg∙g−1), SeCys2 (1.0695∼1.2124 μg∙g−1), SeMeCys (0.7288∼0.7984 μg∙g−1) and SeMet (1.0058∼1.9571 μg∙g−1), accounting for up to 80.14% of total selenium. There was no difference of order of magnitude in the four Se-AAs, indirectly indicating the random incorporation of selenium into selenoprotein LlGPx in L. lactis NZ9000. This work throws new light on the identification and biosynthesis of organic selenium species in selenoproteins and selenium-riched organisms like L. lactis. [ABSTRACT FROM AUTHOR]

This paper is focused on the determination of phthalates (PAEs), compounds “plausibly” endocrine disruptors, in baby food products by means of a method based on ultrasound-vortex-assisted liquid-liquid microextraction coupled with GC-IT/MS (UVALLME-GC-IT/MS). Particularly, the whole procedure allows the determination of six phthalates such as DMP, DEP, DBP, iBcEP, BBP and DEHP. After dissolution of 0.1 g product sample and addition of anthracene as Internal Standard, 250 μL of n -heptane are used as extraction solvent. The solution, held for 5 min on the vortex mixer and for 6 min in an ultrasonic bath at 100 W for favoring the solvent dispersion and consequently the analyte extraction, is centrifuged at 4000 rpm for 30 min. About 100 μL of heptane are recovered and 1 μL is injected into the GC-IT/MS. All the analytical parameters investigated are deeply discussed: under the best conditions, the percentage recoveries range between 96.2 and 109.2% with an RSD ≤10.5% whereas the Limit of Detections (LODs) and the Limit of Quantifications (LOQs) are below 11 and 20 ng g −1 , respectively, for all the PAEs except for iBcEP (23 and 43 ng g −1 , respectively). The linear dynamic range of this procedure is between 10 and 5000 ng g −1 with R 2 ≥0.92. The method has been applied to real commercial freeze-dried samples (chicken and turkey meats) available on the Italian pharmaceutical market: three PAEs were preliminary identified, i.e. DEP (14 ng g −1 ), DBP (11 ng g −1 ) and DEHP (64 ng g −1 ). [ABSTRACT FROM AUTHOR]

Mass spectrometric assays are now of great relevance for trace compound analysis in complex matrices such as serum and plasma samples. Especially in the quantification of low abundant protein-biomarkers, the choice of the sample preparation is crucial. In the present paper immunocapture and Molecular Imprinted Polymers (MIPs) have been applied in the determination of pro-gastrin-releasing peptide, a Small Cell Lung Cancer marker. These affinity-based techniques were compared in terms of matrix effect, limits of detection, repeatability and extraction specificity. In addition, protein precipitation was included for comparison as it is a typical sample preparation method of biological matrices. The results highlighted differences in the methods’ performance and specificity, strongly affecting the outcome of the mass spectrometric determination. Plastic and monoclonal antibodies confirmed to be sensitive and specific sample preparations able to determine ProGRP at clinical relevant concentration, although only the use of monoclonal antibodies allowed the reliable quantification of ProGRP at reference levels (8 pM). In addition better insight in the specificity of the three sample preparation techniques was gained. This might also be of interest for other biological applications. [ABSTRACT FROM AUTHOR]

Oxidation of therapeutic monoclonal antibodies (mAbs) often occurs on surface exposed methionine and tryptophan residues during their production in cell culture, purification, and storage, and can potentially impact the binding to their targets. Characterization of site specific oxidation is critical for antibody quality control. Antibody oxidation is commonly determined by peptide mapping/LC–MS methods, which normally require a long (up to 24 h) digestion step. The prolonged sample preparation procedure could result in oxidation artifacts of susceptible methionine and tryptophan residues. In this paper, we developed a rapid and simple UV based peptide mapping method that incorporates an 8-min trypsin in-solution digestion protocol for analysis of oxidation. This method is able to determine oxidation levels at specific residues of a mAb based on the peptide UV traces within <1 h, from either TBHP treated or UV light stressed samples. This is the simplest and fastest method reported thus far for site specific oxidation analysis, and can be applied for routine or high throughput analysis of mAb oxidation during various stability and degradation studies. By using the UV trace, the method allows more accurate measurement than mass spectrometry and can be potentially implemented as a release assay. It has been successfully used to monitor antibody oxidation in real time stability studies. [ABSTRACT FROM AUTHOR]

The Fischer-Tropsch (FT) process produces a variety of hydrocarbons over a wide carbon number range and during subsequent product workup a large variety of synthetic fuels and chemicals are produced. The complexity of the product slate obtained from this process is well documented and the high temperature FT (HT-FT) process products are spread over gas, oil and water phases. The characterization of these phases is very challenging even when using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS). Despite the increase in separation power, peak co-elution still occurs when samples containing isomeric compounds are analysed by comprehensive two dimensional GC. The separation of isomeric compounds with the same double bond equivalents is especially difficult since these compounds elute in a similar position on the GC × GC chromatogram and have identical molecular masses and similar fragmentation patterns in their electron ionization (EI) mass spectra. On-line hydrogenation after GC × GC separation is a possible way to distinguish between these isomeric compounds since the number of rings and alkene double bonds can be determined from the mass spectra of the compounds before and after hydrogenation. This paper describes development of a GC × GC method with post column hydrogenation for the determination of the backbone of cyclic/olefinic structures enabling us to differentiate between classes like dienes and cyclic olefins in complex petrochemical streams. [ABSTRACT FROM AUTHOR]

Capillary electrophoresis and capillary liquid chromatography coupled to mass spectrometry (CE-MS and CapLC–MS, respectively) are nowadays very suitable techniques for the separation and characterization of intact proteins in biological fluids. In this paper, we compare the performance of both techniques for the analysis of transthyretin (TTR), which is a homotetrameric protein (relative molecular mass (M r ) ∼56,000) involved in different types of amyloidosis. Furthermore, it is also presented a novel sample pretreatment based on immunoprecipitation (IP) using Protein A Ultrarapid Agarose™ (UAPA) magnetic beads (MBs) to purify TTR from serum samples. This novel IP based on MBs allowed the detection of TTR monomeric proteoforms that were not possible to analyze by conventional IP in solution. In addition, UAPA MBs provided many other desirable advantages including higher selectivity and minimal unspecific binding of other proteins. CE-MS and CapLC–MS were applied to analyze serum samples from healthy controls and familial amyloidotic polyneuropathy type I (FAP-I) patients, who suffered from the most common hereditary systemic amyloidosis. Both techniques allowed detecting the same TTR proteoforms, including the mutant TTR (Met 30) variant (variation in relative molecular mass (ΔM r ) was +32.07, from wild-type TTR). Migration/retention times and relative quantitation of the different proteoforms were similar and reproducible in both cases, but the limits of detection (LODs) achieved by CE-MS were slightly lower (2–2.5-fold). Some other differences were also found on separation selectivity (migration orders and separation of antibody), peak efficiency, total analysis time, calibration ranges and experimental M r accuracy. [ABSTRACT FROM AUTHOR]

This paper, for the first time, reported a speedy hyphenated technique of low toxic dual ultrasonic-assisted dispersive liquid–liquid microextraction (dual-UADLLME) coupled with microwave-assisted derivatization (MAD) for the simultaneous determination of 20( S )-protopanaxadiol (PPD) and 20( S )-protopanaxatriol (PPT). The developed method was based on ultra high performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) detection using multiple-reaction monitoring (MRM) mode. A mass spectrometry sensitizing reagent, 4′-carboxy-substituted rosamine (CSR) with high reaction activity and ionization efficiency was synthesized and firstly used as derivatization reagent. Parameters of dual-UADLLME, MAD and UHPLC-MS/MS conditions were all optimized in detail. Low toxic brominated solvents were used as extractant instead of traditional chlorinated solvents. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect and extremely low limits of detection (LODs, 0.010 and 0.015 ng/mL for PPD and PPT, respectively) were achieved. The main advantages were rapid, sensitive and environmentally friendly, and exhibited high selectivity, accuracy and good matrix effect results. The proposed method was successfully applied to pharmacokinetics of PPD and PPT in rat plasma. [ABSTRACT FROM AUTHOR]

This paper demonstrates a method for the rapid separation and identification of four microcystin (MC) variants commonly found in aquatic environments. The procedure utilizes capillary electrophoresis (CE) coupled to UV absorbance and time-of-flight mass spectrometric (TOF–MS) detectors. All four analytes were effectively separated within 6 min using phosphate buffer in 50-μm ID capillaries with an applied electric field of 400 V/cm. The separation of the individual compounds was optimized through the adjustment of buffer, pH, and β-cyclodextrin content. Ultimately it was determined that, at a sufficiently high pH, all 4 compounds could be separated without the need for added cyclodextrins. The results provided accurate molecular information, assisting in the determination of compound identity. The method was then applied to environmental samples using solid phase extraction for isolation and pre-concentration. The results were comparable to those obtained by LC/MS, but with a shorter run time and lower sample and eluent consumption. [ABSTRACT FROM AUTHOR]

In this paper, heart-cutting two-dimensional GC/MS (GC–GC/MS) method in combination with a simple sample collection procedure was developed for the determination of 6 nitroalkanes in mainstream cigarette smoke. The method could remove large amounts of impurities on-line in the first polar column by heart-cuts and separate from the left interferences in a second mid-polar column. And the target compounds could be focused at the inlet of the second column by cryo-concentration. Compared to conventional GC/MS, GC–GC/MS achieved a lower noise level and sensitivity at least an order of magnitude higher. Furthermore, the GC–GC/MS method could avoid the false negative and false positive results that appeared in the compared conventional GC/MS analysis. By trapping the vapor phase of 20 cigarettes smoke, the LODs and LOQs of the nitroalkanes were 1.3 to 9.8 and 4.3 to 32.6 ng/cigarette, respectively, and all linear correlation efficiencies were larger than 0.999. The validation results also indicate that the method has high accuracy (spiked recoveries between 84% and 102%) and good repeatability (RSD between 7.2% and 9.4%). The developed method was applied to analyze 1 Kentucky reference cigarette (3R4F) and 10 Chinese commercial brands of cigarettes. The research results indicated that nitromethane, nitroethane, 2-nitropropane and 1-nitro- n -pentane were detected in mainstream cigarette smoke, but 1-nitro- n -butane and 2-nitropropane, which were reported by one previous study, were not detected in all cigarette samples. [ABSTRACT FROM AUTHOR]

• Analysis of drug absorption and retention in cancer cells for preclinical studies. • Isolation of a group of drugs with different physicochemical properties from cancer cells. • Repositioning of drugs using a new method of isolation and analysis from biological matrices. The presented paper describes a new isolation method of recovery and analysis of selected drugs developed for preclinical research. The method uses the RP-HPLC technique (in a single chromatographic separation) and serves the recovery and analysis of selected drugs from neoplastic cells. It enables the determination of cytostatics statins, fibrates, and pioglitazone. Chromatographic separations of the tested compounds were carried out on a Gemini-NX 5 µ C18 (4.6 × 150 mm i.d.) column, in a gradient system with a mobile phase consisting of ACN (0.1% TFA) and water (0.1% TFA) at ambient temperature. The separations were carried out at a flow of 1 ml/min and UV detection of 220 nm. The inter-day and intra-day precision and accuracy of the method were determined. Extending the extraction time at reduced temperature resulted in a significant increase in the recovery of the pharmaceuticals in comparison with traditional extraction methods. The presence of the tested pharmaceuticals at defined retention times was confirmed by mass spectrometry. A recovery procedure for the tested compounds from biological material (medium, cell pellets) was developed at a level ranging between 93 and 99%. The utility of the new HPLC method has been confirmed in drug absorption studies as screening tests for the analysis of the new therapeutic compositions on melanoma cell lines. [ABSTRACT FROM AUTHOR]

This paper reports our effort to develop a comprehensive HPLC-MS n -based dereplication strategy for phorbol ester (PE), deoxyphorbol ester (dPE) and ingenol ester (IE) profiling in plant extracts. This strategy is composed of two sequential analysis exploiting specific hybrid triple quadrupole/linear ion trap instrument modes. A first run was performed using a multiple reaction monitoring (MRM) mode targeting fragmentation of PE and dPE/IE coupled with the acquisition of MS 2 spectrum for the ions at m / z 311 and m/z 313, respectively. A second run was then completed based on precursor ion scan mode (PIS) and automatic MS 2 acquisition for each quasimolecular ion. The developed approach was used to investigate ten Euphorbia extracts showing bioactivity against chikungunya virus replication. Experiments allowed partial annotation of three dPE/IE but no PE was detected. Results suggested that other types of diterpene esters displayed PE- and dPE/IE-like fragmentations. The study of jatrophane ester (JE) standards by CID fragmentation using low and high resolution mass spectrometry confirmed this hypothesis, highlighting challenges and difficulties of diterpene esters profiling within plant extracts. Nonetheless, the present LC–MS n method can be easily adapted to profile other types of diterpene esters. [ABSTRACT FROM AUTHOR]

Metabolomics GC–MS samples involve high complexity data that must be effectively resolved to produce chemically meaningful results. Multivariate curve resolution-alternating least squares (MCR-ALS) is the most frequently reported technique for that purpose. More recently, independent component analysis (ICA) has been reported as an alternative to MCR. Those algorithms attempt to infer a model describing the observed data and, therefore, the least squares regression used in MCR assumes that the data is a linear combination of that model. However, due to the high complexity of real data, the construction of a model to describe optimally the observed data is a critical step and these algorithms should prevent the influence from outlier data. This study proves independent component regression (ICR) as an alternative for GC–MS compound identification. Both ICR and MCR though require least squares regression to correctly resolve the mixtures. In this paper, a novel orthogonal signal deconvolution (OSD) approach is introduced, which uses principal component analysis to determine the compound spectra. The study includes a compound identification comparison between the results by ICA-OSD, MCR-OSD, ICR and MCR-ALS using pure standards and human serum samples. Results shows that ICR may be used as an alternative to multivariate curve methods, as ICR efficiency is comparable to MCR-ALS. Also, the study demonstrates that the proposed OSD approach achieves greater spectral resolution accuracy than the traditional least squares approach when compounds elute under undue interference of biological matrices. [ABSTRACT FROM AUTHOR]