Search

[Display omitted] • Chemical profiling of different paper grades was performed along the recycling chain. • Untargeted analysis of semi-volatiles and non-volatiles using GC- and LC-MS. • Chemometrics application to identify specific features by paper grade and site. • Exploration of the possible sources of detected compounds in the paper recycling chain. • Numerous chemical compounds associated with plastics have been detected. Paper packaging made with recycled paperboard is used to pack various consumer goods that can include amongst others, electronics, toys, food, cosmetics, and stationery. Chemical profiling of the various paper recycling grades used in the manufacture of recycled paperboard was undertaken to investigate possible sources of contaminants and their propagation in the paper recycling chain. Pre-consumer, retail and post-consumer paper-based materials were collected at papermills, corrugators, grocery stores, household waste, solid waste disposal sites and recycling facilities. In the GC-MS analysis, phthalates, long-chain aliphatic compounds, and fatty acids were the most commonly detected compounds whilst phthalates and bisphenols featured most prevalently in the LC-MS analysis. The factors that were identified as likely contributors to the detection of the different chemical compounds included the presence of wood derivatives, the use of certain chemical additives during manufacturing, and exposure of paper to contaminants from consumers, other goods and the environment. Waste mingling, recovery, sorting and reprocessing into recycled paper were also shown to influence the chemical profile of paper materials. Sparse partial least squares-discriminate analysis indicated that newspaper and office paper had unique chemical constituents, whilst cartons were shown to have higher variability. By looking at key stages of paper recycling, this study showed that the possible persistence and transformation of chemical compounds in additives must be evaluated when considering the recyclability of paper-based materials. Further, it highlighted that different separation approaches may be required to reduce contaminant exposure opportunities in post-consumer paper materials. [ABSTRACT FROM AUTHOR]

As a prescription drug, retinoic acid is listed as a banned cosmetic additive in the EU and China regulations. Currently, spectrophotometric methods, including thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and HPLC–MS/MS, are commonly used for the determination of retinoic acid. As these conventional methods require complex pretreatment and are time-consuming, chemical derivatization combined with paper spray ionization mass spectrometry was developed for the fast detection of retinoic acid in cosmetics. N,N-dimethylpiperazine iodide (DMPI) was utilized as a derivatization reagent. Carboxylic acid in retinoic acid was derivatized to carry a positive charge and was subjected to mass spectrometry analysis. Results showed that compared with non-derivatized compounds, the detection limit was increased by about 50 times. The linearity in the range of 0.005–1 μg·mL−1 was good. The limit of detection (LOD) was 0.0013 μg·mL−1, and the limit of quantification (LOQ) was 0.0043 μg·mL−1. The recoveries of spiked samples were in the range of 95–105%, and the RSDs were below 5%. Derivatization and paper spray ionization MS render a quick, sensitive, and accurate method for the detection of retinoic acid in a complex matrix. [ABSTRACT FROM AUTHOR]

We developed a simple, paper‐based device that enables sensitive detection by mass spectrometry (MS) without solid phase extraction or other sample preparation. Using glass fiber filter papers within a 3D printed holder, the device employs electrokinetic manipulations to stack, separate, and desalt charged molecules on paper prior to spray into the MS. Due to counter‐balanced electroosmotic flow and electrophoresis, charged analytes stack on the paper and desalting occurs in minutes. One end of the paper strip was cut into a sharp point and positioned near the inlet of a MS. The stacked analyte bands move toward the paper tip with the EOF where they are ionized by paper spray. The device was applied to analysis of PFAS in tap water with sub part‐per‐trillion detection limits in less than ten minutes with no sample pretreatment. Analysis of opioids in urine also occurs in minutes. The crucial parameters to enable stacking, separation, and MS ionization of both positively and negatively charged analytes were determined and optimized. Experimental and computational modeling studies confirm the electrokinetic stacking and analyte transport mechanisms. On‐paper separations were carried out by stacking analyte bands at different locations depending on their electrophoretic mobility, achieving baseline separation in some cases. [ABSTRACT FROM AUTHOR]

We developed a simple, paper‐based device that enables sensitive detection by mass spectrometry (MS) without solid phase extraction or other sample preparation. Using glass fiber filter papers within a 3D printed holder, the device employs electrokinetic manipulations to stack, separate, and desalt charged molecules on paper prior to spray into the MS. Due to counter‐balanced electroosmotic flow and electrophoresis, charged analytes stack on the paper and desalting occurs in minutes. One end of the paper strip was cut into a sharp point and positioned near the inlet of a MS. The stacked analyte bands move toward the paper tip with the EOF where they are ionized by paper spray. The device was applied to analysis of PFAS in tap water with sub part‐per‐trillion detection limits in less than ten minutes with no sample pretreatment. Analysis of opioids in urine also occurs in minutes. The crucial parameters to enable stacking, separation, and MS ionization of both positively and negatively charged analytes were determined and optimized. Experimental and computational modeling studies confirm the electrokinetic stacking and analyte transport mechanisms. On‐paper separations were carried out by stacking analyte bands at different locations depending on their electrophoretic mobility, achieving baseline separation in some cases. [ABSTRACT FROM AUTHOR]

Sulfite, a widely used food additive, is subject to regulated labeling. The extraction of sulfite as the stable hydroxymethylsulfonate (HMS) form and its quantitative analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been recognized for their good sensitivity, selectivity, and versatility across various food materials. This study aimed to develop a cost-effective and simpler method for sulfite quantitation, while maintaining the superior sensitivity and selectivity of mass spectrometry (MS). To achieve this, we introduced paper spray ionization (PSI), an ambient desorption ionization technique that could achieve the direct measurement of analytes without employing separation. We also employed a novel internal standard (IS) structurally similar to the analyte, replacing the more expensive isotopically labeled IS. Although the PSI-MS/MS method developed in this study exhibited slightly lower analytical performance compared to the conventional LC-MS/MS, it remained effective for sulfite analysis in dried fruits. [ABSTRACT FROM AUTHOR]

Capturing short‐lived intermediates at the molecular level is key to understanding the mechanism and dynamics of chemical reactions. Here, we have developed a paper‐in‐tip bipolar electrolytic electrospray mass spectrometry platform, in which a piece of triangular conductive paper incorporated into a plastic pipette tip serves not only as an electrospray emitter but also as a bipolar electrode (BPE), thus triggering both electrospray and electrolysis simultaneously upon application of a high voltage. The bipolar electrolysis induces a pair of redox reactions on both sides of BPE, enabling both electro‐oxidation and electro‐reduction processes regardless of the positive or negative ion mode, thus facilitating access to complementary structural information for mechanism elucidation. Our method enables real‐time monitoring of transient intermediates (such as N,N‐dimethylaniline radical cation, dopamine o‐quinone (DAQ) and sulfenic acid with half‐lives ranging from microseconds to minutes) and transient processes (such as DAQ cyclization with a rate constant of 0.15 s−1). This platform also provides key insights into electrocatalytic reactions such as Fe (III)‐catalyzed dopamine oxidation to quinone species at physiological pH for neuromelanin formation. [ABSTRACT FROM AUTHOR]

Capturing short‐lived intermediates at the molecular level is key to understanding the mechanism and dynamics of chemical reactions. Here, we have developed a paper‐in‐tip bipolar electrolytic electrospray mass spectrometry platform, in which a piece of triangular conductive paper incorporated into a plastic pipette tip serves not only as an electrospray emitter but also as a bipolar electrode (BPE), thus triggering both electrospray and electrolysis simultaneously upon application of a high voltage. The bipolar electrolysis induces a pair of redox reactions on both sides of BPE, enabling both electro‐oxidation and electro‐reduction processes regardless of the positive or negative ion mode, thus facilitating access to complementary structural information for mechanism elucidation. Our method enables real‐time monitoring of transient intermediates (such as N,N‐dimethylaniline radical cation, dopamine o‐quinone (DAQ) and sulfenic acid with half‐lives ranging from microseconds to minutes) and transient processes (such as DAQ cyclization with a rate constant of 0.15 s−1). This platform also provides key insights into electrocatalytic reactions such as Fe (III)‐catalyzed dopamine oxidation to quinone species at physiological pH for neuromelanin formation. [ABSTRACT FROM AUTHOR]

Turmeric and ginger are extensively employed as functional ingredients due to their high content of curcuminoids and gingerols, considered the key bioactive compounds found in these roots. In this study, we present an innovative and fast method for the assay of curcuminoids and gingerols in different foods containing the two spices, with the aim of monitoring the quality of products from a nutraceutical perspective. The proposed approach is based on paper spray tandem mass spectrometry coupled with the use of a labeled internal standard, which has permitted to achieve the best results in terms of specificity and accuracy. All the calculated analytical parameters were satisfactory; accuracy values are around 100% for all spiked samples and the precision data result lower than 15%. The protocol was applied to several real samples, and to demonstrate its robustness and reliability, the results were compared to those arising from the common liquid chromatographic method. [ABSTRACT FROM AUTHOR]

Introduction: Distinguishing and categorizing the origin of garlic are highly significant, considering its widespread use as a flavoring agent. With billions of dollars annually in global trade, garlic is frequently susceptible to fraudulent practices. Methodology: Paper spray ionization mass spectrometry (PS‐MS) was employed to quickly analyze garlic samples from distinct geographic origins: China and Brazil. The so‐generated PS‐MS data were treated with metabolomic multivariate approaches, and the garlic samples from these different geographic regions were easily discriminated. Results: Brazilian garlic was characterized to contain higher levels of amino acids, such as arginine, proline, and valine, and organosulfur compounds, such as allicin, alliin, and l‐γ‐glutamil‐S‐allyl‐l‐cysteine, compared to Chinese garlic. The PS‐MS data were treated employing multivariate approaches, typically used in the metabolomics field, and this protocol was promptly able to discern among both types of samples. Conclusion: Hence, this combined strategy holds promise not only as an effective tool for the authentication of the geographical origin of garlic but also as a powerful means for biomarker discovery. [ABSTRACT FROM AUTHOR]

An unprecedented and direct PS‐MS (paper spray ionization mass spectrometry) method was proposed for the detection of native peptides, that is, glutathiones (GSHs), homoglutathiones (hGSHs), and phytochelatins (PCs), in basil (Ocimum basilicum L.) roots before and after cadmium exposure. The roots were submitted to cold maceration followed by sonication with formic acid as the extractor solvent for sample preparation. PS‐MS was used to analyze such extracts in the positive mode, and the results allowed for the detection of several GSHs, hGSHs, and PCs. Some of these PCs were not distinguished in the control samples, that is, basil roots not exposed to cadmium. Other PCs were noticed in both types of roots, uncontaminated and cadmium‐contaminated, but the intensities were higher in the former samples. Moreover, long‐time exposure to cadmium stimulated the formation of some of these PCs and their cadmium complexes. The results, therefore, provided some crucial insights into the defense mechanism of plants against an external stress condition due to exposure to a toxic heavy metal. The present study represents a promising alternative to investigate other crucial physiological processes in plants submitted to assorted stress conditions. [ABSTRACT FROM AUTHOR]

A new analytical method for chronic kidney disease (CKD) detection utilizing paper spray mass spectrometry (PS-MS) combined with machine learning is presented. The analytical protocol is rapid and simple, based on metabolic profile alterations in urine. Anonymized raw urine samples were deposited (10 μL each) onto pointed PS-MS sample strips. Without waiting for the sample to dry, 75 μL of acetonitrile and high voltage were applied to the strips, using high resolution mass spectrometry measurement (15 s per sample) with polarity switching to detect a wide range of metabolites. Random forest machine learning was used to classify the resulting data. The diagnostic performance for the potential diagnosis of CKD was evaluated for accuracy, sensitivity, and specificity, achieving results >96% for the training data and >91% for validation and test data sets. Metabolites selected by the classification model as up- or down-regulated in healthy or CKD samples were tentatively identified and in agreement with previously reported literature. The potential utilization of this approach to discriminate albuminuria categories (normo, micro, and macroalbuminuria) was also demonstrated. This study indicates that PS-MS combined with machine learning has the potential to be used as a rapid and simple diagnostic tool for CKD. [ABSTRACT FROM AUTHOR]

Paper spray ionization mass spectrometry (PSI MS) has emerged as a notable method for the rapid analysis of biological samples. However, the typical cellulose-based paper tip is incompatible with protein detection due to the strong interaction between cellulose hydroxyl groups and proteins. In this study, we utilized a commercially available polyolefin-based synthetic paper, Teslin®, as an alternative PSI substrate for simple protein analysis. We have named this method "droplet PSI" MS, as the aqueous protein solution droplet retains its shape on the Teslin® paper tip. For droplet PSI, no further chemical pretreatment was necessary for the Teslin® substrate; the only required preparation was shaping the Teslin® paper into a triangular tip. In droplet PSI MS, protein ion signals were instantly detected from a protein solution droplet upon applying a spray solvent in situ along with high voltage (HV). When compared with conventional PSI MS, our method demonstrated superior sensitivity. The droplet PSI MS utilizing Teslin® also showcased flexibility in real-time observation of protein alterations induced by an acid additive. Additionally, the effects of spray solvent composition and the application method were discussed. [ABSTRACT FROM AUTHOR]

Albuminuria is a clinical condition associated with poor kidney function, diagnosed by determining the ratio of albumin to creatinine concentrations in patient urine samples. We present a high-throughput paper spray mass spectrometry (PS-MS) method for simultaneous quantitation of urinary albumin and creatinine for potential diagnosis of albuminuria. Minimal (urine dilution) or no sample preparation is required. The analytical performance of the method was evaluated, achieving linear calibration curves (R2 > 0.99) with little inter-day variability in the slope (N = 5 days), exhibiting coefficient of variation (CV) of 8% and 3% for albumin and creatinine, respectively. LOD and LOQ for albumin were 2.1 and 7.0 mg L−1, and for creatinine were 0.01 and 0.03 mmol L−1, respectively. Intra- and inter-day (N = 5) precisions (%CV) and accuracies (%bias) were <10% and ±11%, respectively, for both analytes. The method was applied to determine albumin-to-creatinine ratios in anonymous human patient urine samples (N = 56), and a correlation of R2 = 0.9744 was achieved between the PS-MS results and validated clinical method results. This work demonstrates the utility of PS-MS to simultaneously quantify a large (albumin) and a small (creatinine) molecule directly in patient urine samples, and its potential as a tool for clinical albuminuria diagnostics. [ABSTRACT FROM AUTHOR]

A simple, rapid chemical coating and patterning method was developed and optimized for paper-based substrates for use in paper spray mass spectrometry (PS-MS). A variety of chlorosilanes were explored for coating paper substrates, and their effectiveness in forming hydrophobic surfaces was characterized via contact angle goniometry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Trichloromethylsilane was selected as the primary coating agent because of the short time required to produce a hydrophobic surface (contact angle > 130°), as well as the ease of patterning. Patterning was performed using 3D-printed masks and an oxygen/plasma cleaner. Optimal mask thickness and oxygen/plasma cleaning parameters were determined to produce channels varying from 0.5 to 2.5 mm in width. The effectiveness of the patterned substrates for PS-MS was determined via analysis of four antiretrovirals: emtricitabine, lamivudine, efavirenz, and dolutegravir. Calibration curves were made for each antiretroviral at varying channel widths, and the limits of detection and limits of quantification for each drug were determined. These results show that this patterning method results in an average 7.2-fold improvement in sensitivity and an average 190-fold improvement in limits of detection over uncoated paper substrates in a neat matrix. In a proof-of-concept experiment, calibration curves were generated for each antiretroviral in urine. A patterned paper substrate with a 2-mm channel resulted in an average 7.4-fold improvement in sensitivity and an average 18-fold improvement in limits of detection over uncoated paper substrates. [ABSTRACT FROM AUTHOR]

A new method was proposed for point-of-care testing (POCT) of immunosuppressants in blood using thin-layer paper spray ionization and a miniature mass spectrometer. The aluminum thin-layer plate was used as paper spray substrate, and cut into an equilateral triangle. Aliquots of 10 μL blood sample were loaded on the aluminum thin-layer plate, and then 20 μL methanol was dropped as elution/spray solvent. The tip of the triangular plate was placed 1.0 cm in front of the discontinuous atmospheric pressure interface (DAPI) of the miniature mass spectrometer. When the spray voltage was applied, the sample was eluted from the triangular plate and formed paper spray ionization at the tip. Coupled with the miniature mass spectrometer, five immunosuppressants were detected under negative ion mode. The precursor ions ［M-H］- of tacrolimus, sirolimus, everolimus, ciclosporin A, and mycophenolic acid are m/z 802.6, 912.6, 957.1, 1 200.8, 319.1, and product ions are m/z 560.2 and 604.3, m/z 590.3 and 321.2, m/z 590.3 and 365.2, m/z 1 088.8, m/z 287.4 and 275.1, respectively. Based on the observed signal-to-noise ratio (S/N) of the most intense tandem mass spectrometry (MS/MS) fragment peaks and using the S/N=3 and 10 as the criteria, the limits of detection (LODs) and quantitation (LOQs) are estimated to be 0.5-5 mg/L and 1-10 mg/L, respectively. The internal standard method was used for quantitative analysis, and indapamide was used as the internal standard compound. Sufficient linearity for each analyte is obtained with the correlation coefficients (r) greater than 0.99. The proposed method displays good recoveries in the range of 91.0%-114.3% with the relative standard deviations (RSDs) less than 8.4%. Moreover, the developed method was used for the analysis of blood samples, which spiked with tacrolimus, sirolimus, everolimus, cyclosporine A and mycophenolic acid at the concentration of 100 mg/L. The analytical results demonstrated the consistency between the proposed method and the traditional liquid chromatography-mass spectrometry (LC-MS) method. The entire analysis procedure can be completed within 1 min. The proposed method is simple, fast, accurate, efficient, and suitable for POCT of immunosuppressants in blood. [ABSTRACT FROM AUTHOR]

Criminal practices in which an individual becomes vulnerable and prone to sexual assault after ingesting drinks spiked with doping substances have become a social concern globally. As forensic protocols require a multi‐tiered strategy for chemical evidentiary analysis, the backlog of evidence has become a significant problem in the community. Herein, a fast, sensible, and complementary dual analytical methodology was developed using a single commercial paper substrate for surface‐enhanced Raman spectroscopy (SERS) and paper spray mass spectrometry (PS‐MS) analysis to identify psychotropic substances added to alcoholic beverages irrefutably. To study and investigate this criminal practice, pharmaceutical formulations containing distinct psychotropic substances (zolpidem, clonazepam, diazepam, and ketamine) were added to drinks typically consumed at parties and festivals (Pilsen beer, açaí Catuaba®, gin tonic, and vodka mixed with Coca‐Cola Zero®). A simple liquid–liquid extraction with a low‐temperature partitioning (LLE‐LTP) procedure was applied to the drinks and effectively minimized matrix effects. As a preliminary analysis, SERS spectra combined with Hierarchical Clustering Analysis (HCA) provided sufficient information to investigate the samples further. The presence of the protonated species for the psychotropic substances in the spiked drinks was readily verified in the mass spectra and confirmed by tandem mass spectrometry. Finally, the results demonstrate the potential of this methodology to be easily implemented into the routine of forensic laboratories and to be further employed at harm reduction tends at parties and festivals to detect contaminated beverages promptly and irrefutably as an efficient tool to prevent such crimes. [ABSTRACT FROM AUTHOR]

Paracetamol overdose is a leading cause of acute liver failure that can prove fatal. Establishing paracetamol concentration accurately and quickly is critical. Current detection methods are invasive, time-consuming and/or expensive. Non-invasive, rapid and cost-effective techniques are urgently required. To address this challenge, a novel approach, called Paper-Arrow Mass Spectrometry (PA-MS) has been developed. This technique combines sample collection, extraction, enrichment, separation and ionisation onto a single paper strip, and the entire analysis process, from sample to result, can be carried out in less than 10 min requiring only 2 μL of raw human saliva. PA-MS achieved a LOQ of 185 ng mL−1, mean recovery of 107 ± 7%, mean accuracy of 11 ± 8% and precision ≤5% using four concentrations, and had excellent linearity (r2 = 0.9988) in the range of 0.2–200 μg mL−1 covering the treatment concentration range, surpassing the best-in-class methods currently available for paracetamol analysis. Furthermore, from a panel of human saliva samples, inter-individual variability was found to be <10% using this approach. This technique represents a promising tool for rapid and accurate emergency diagnosis. [ABSTRACT FROM AUTHOR]

The rise of fentanyl and fentanyl analogs in the drug supply pose serious threats to public health. Much of these compounds enter the United States through shipping routes. Here we provide a method for fentanyl screening and analysis that utilizes pressure‐sensitive adhesive (PSA) lined paper to recover drug residues from parcel‐related surfaces. The paper used is commercially available repositionable notes (also called post‐it or sticky notes). From this paper, mass spectra were obtained by paper spray‐mass spectrometry (PS‐MS), where PSA paper served as both a sampling and analysis substrate. Seven fentanyl‐related compounds were analyzed: fentanyl, 4‐anilino‐N‐phenethylpiperidine (4‐ANPP), N,1‐diphenethyl‐N‐phenylpiperidin‐4‐amine (phenethyl‐4‐ANPP), valerylfentanyl, 4‐fluoroisobutyrylfentanyl (4‐FIBF), carfentanil, and p‐fluorofentanyl. These compounds were recovered by PSA paper and identified by PS‐MS from packaging tape and plastic at 50 ng and from cardboard and shipping labels at 100 ng. The impact of cutting agents on PS‐MS analysis of fentanyl analogs was explored. No trends of analyte suppression were found at high concentrations of the cutting agents caffeine, diphenhydramine, and lidocaine when recovered from surfaces. A cartridge that required no precise cutting of PSA paper prior to sampling or analysis was evaluated for use in PS‐MS for fentanyl screening. Recovery and detection of fentanyl from plastic sheeting was demonstrated with this cut‐free cartridge. The cut‐free cartridge showed somewhat less consistency and lower analyte signal than the standard cartridge, but performance was suitable for potential screening applications. In combining PSA surface sampling with PS‐MS for drug screening, both sampling and detection of fentanyl‐related compounds is simple, rapid, and low‐cost. [ABSTRACT FROM AUTHOR]

Rapid detection of harmful estrogens in cosmetics is essential in protecting public health. To reduce time-consuming pretreatment and analytical procedures, a novel reactive paper spray ionization mass spectrometry (RPSI-MS) methodology was developed. RPSI-MS is suitable for quantitatively analyzing estrogens in cosmetics by utilizing an online derivatization reaction between estrogens and 2-fluoro-1-methyl-pyridinium-p-toluene-sulfonate (FluMP). Using estradiol valerate as the internal standard (I.S.), three estrogens, estradiol, estriol, and ethinyloestradiol, in cosmetics were quantitatively characterized within minutes. Multiple parameters were optimized including FluMP concentration and volume, triethylamine amount as well as the drying time. The three estrogens displayed good linearity ranging from 0.002 to 1 μg/mL, with R2 above 0.99. The recovery results of all the estrogens were within 80~111%. The limit of detection (LOD) was 0.001 μg/mL for the three estrogens. Compared to conventional paper spray ionization mass spectrometry (PSI-MS), extraction is not required and the detection sensitivity of RPSI-MS was improved by 34,000, 80,000, and 1400 times for estradiol, estriol, and ethinyloestradiol, respectively. The protocol established in this paper is sensitive, eco-friendly, and suitable for rapid testing of estrogens in cosmetics. [ABSTRACT FROM AUTHOR]

Rationale: The burgeoning concern of N‐nitrosamine (NAM) contamination found in various pharmaceutical compositions has increased the demand for rapid and reliable screening methods to better assess the breadth of the problem. These carcinogenic compounds are also found in food, water, and soil, and they have been used in poison‐related homicides. Methods: A combination of complementary, ambient ionization methods, paper spray ionization (PSI) and filter cone spray ionization (FCSI)‐mass spectrometry (MS), was characterized towards trace‐level residue screening of select NAMs (e.g., N‐nitrosodimethylamine, N‐nitrosodiethylamine, N‐nitrosodibutylamine) directly from complex and problematic matrices of interest, including prescription and over‐the‐counter tablets, drinking water, soil, and consumable goods. Spectral data for analyte confirmation and detection limit studies were collected using a Thermo LCQ Fleet ion trap mass spectrometer. Results: PSI‐MS and FCSI‐MS readily produced mass spectral data marked by their simplicity (e.g., predominantly protonated molecular ions observed) and congruence with traditional electrospray ionization mass spectra in under 2 min. per sample. Both methods proved robust to the complex matrices tested, yielding ion signatures for target NAMs, as well as active pharmaceutical ingredients for analyzed tablets, flavorants inherent to food products, etc. Low part‐per‐million detection limits were observed but were shown dependent on sample composition. Conclusions: PSI‐MS and FCSI‐MS were successful in detecting trace‐level NAMS in complex liquid‐ and solid‐phase matrices with little to no prior preparation. This work suggests that these methodologies can provide a means for assessing problematic pharmaceutical adulterants/degradants for expedited quality control, as well as enhancing environmental stewardship efforts and forensic investigations. [ABSTRACT FROM AUTHOR]

Paper spray mass spectrometry (PS‐MS) is an ambient ionization technique that allows for rapid and direct mass spectrometry analysis for a wide range of chemical compounds due to its portability, little to no sample preparation, and cost‐effective materials. As applications with this technique continue to expand, the identification and discrimination of bacteria at the strain level remain a promising avenue for researchers. Although studies in the past demonstrated the applicability of PS‐MS to discriminate bacteria at the strain level, no one has reported the strain‐level differentiation of actinobacteria without using solvent for PS‐MS. Hence, this study demonstrates that optimization of PS‐MS permits the investigation and differentiation of the metabolic profiles of actinobacteria without the need for solvents, diminishing the potential for sample contamination and consequently increasing the versatility of this technique. In doing so, strains of actinobacteria (CAAT P5–21, CAAT P5–16, CAAT 8–25, CAAT P8–92, and CAAT P11–13) were grown and transferred to produce a crude growth medium. The supernatant was used for the PS‐MS analyses using a Thermo Scientific LTQ mass spectrometer. Multivariate statistical analysis, including principal component analysis (PCA) and hierarchal cluster analysis (HCA), was employed to chemically distinguish the strains of bacteria. As a result, each strain of actinobacteria could be visually differentiated based on their metabolic profile. These findings demonstrate the practicability of using a liquid medium as an alternative to many other organic solvents when analyzing bacteria, making PS‐MS a crucial addition to a microbiologist's research toolkit. [ABSTRACT FROM AUTHOR]

In this paper, paper microfluidic channel fabricated by directly screen-printing of polydimethylsiloxane (PDMS) is proposed for paper spray mass spectrometry analysis of therapeutic drugs in the blood samples. Compared with traditional paper spray, PDMS-printed paper spray (PP-PS) allows fluid to flow to the tip of paper with less sample loss which significantly improved the signal intensity of target compounds in blood samples. As paper can reduce the matrix effect, PP-PS also has a greater advantage than electro-spray Ionization (ESI) when directly analyzing complex biological sample in terms of the detection efficiency. Linearity and limits of detection (LOD) were evaluated for five psychotropic drugs: olanzapine, quetiapine, 9-hydroxyrisperidone, clozapine, risperidone. As a result, PP-PS improved the signal intensity of the psychotropic drugs at a concentration of 250 ng/ml in blood samples by a factor of 2–5 times and lowered the relative standard deviation (RSD) by a factor of 2–5.6 times compared with traditional paper spray. And PP-PS also improved signal intensity by a factor of 9–33 times compared with ESI. Quantitative experiments of PP-PS mass spectrometry indicated that the linear range was 5–500 ng/ml and the LOD were improved by a factor of 5–71 times for all these drugs compared with traditional paper spray. In addition, PP-PS was applied to the home-made miniaturized mass spectrometer and the precursor ions of all five psychotropic drugs (250 ng/ml) in the mass spectrometry results were obtained as well. These could prove that PP-PS has the potential to analyze complex biological samples in application on the miniaturized mass spectrometer which can be used outside the laboratory. [Display omitted] • Low-cost PDMS-printed paper spray (PP-PS) device was proposed for mass spectrometry analysis. • The proposed PP-PS device improves the quantitative performances and LODs for therapeutic drug detection in blood samples. • The proposed PP-PS device is also suitable for miniaturized mass spectrometer for on-site applications. [ABSTRACT FROM AUTHOR]

Hypericum perforatum L. (St. John's wort) is one of the world's most consumed medicinal plants for treating depression and psychiatric disorders. Counterfeiting can occur in the medicinal plant trade, either due to the lack of active ingredients or the addition of substances not mentioned on the labels, often without therapeutic value or even harmful to health. Hence, 43 samples of St. John's wort commercially acquired in different Brazilian regions and other countries were analyzed by paper spray ionization mass spectrometry (PS‐MS) and modeled by principal component analysis. Hence, samples (plants, capsules, and tablets) were extracted with ethanol in a solid–liquid extraction. For the first time, PS‐MS analysis allowed the detection of counterfeit H. perforatum samples containing active principles typical of other plants, such as Ageratum conyzoides and Senna spectabilis. About 52.3% of the samples were considered adulterated for having at least one of these two species in their composition. Furthermore, out of 35 samples produced in Brazil, only 13 were deemed authentic, having only H. perforatum. Therefore, there is a clear need to improve these drugs' quality control in Brazil. [ABSTRACT FROM AUTHOR]

Analytical studies of ancient Chinese handmade papers and paper-based materials have long faced challenges, due to the need for high-quality, scientifically sound data that can lead to suitable diagnostic criteria. This study applies Herzberg staining, micro-computed tomography (micro-CT), Raman spectroscopy, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), and high-resolution mass spectrometry (HRMS) to five Hetian Administration Banknotes (HABs), a particular type of regional banknotes issued by Ma Hu-shan (1910–1954), a Hui warlord, in southern Xinjiang between 1933 and 1937. The results shed important insights into the use of fiber and dyes on HABs, revealing how locally handmade Sangpi (bark of the mulberry tree, Morus alba L.) papers and imported synthetic dyes (Rhodamine B, Methyl Violet 2B, Direct Black 38, and presumably Sudan II) were combined to serve the needs of the regional economy in southern Xinjiang during the 1930s. We conclude the paper by tentatively proposing guidelines for applying low- and high-resolution analytical methods to understand the manufacture and use of ancient Chinese handmade papers and paper-based materials. [ABSTRACT FROM AUTHOR]

Paper spray mass spectrometry (PS-MS) has been shown to be a rapid, simple and inexpensive alternative to traditional forensic drug screening methods. It can address the limitations of both immunoassays and chromatography-based techniques due to its non-reliance on sample preparation and its ability to rapidly screen for a wide array of compounds. In this study, an automated PS-MS system was employed to semi-quantitatively screen for 40 commonly abused drugs and metabolites in urine after a 15-min glucuronidase reaction. The target compounds included common prescription opioids, fentanyl and norfentanyl, stimulants including methamphetamine and cocaine, benzodiazepines and antidepressants. The enzyme, buffer and internal standard solution were combined in one spiking solution to minimize sample handling. Analysis was carried out using a commercially available automated paper spray system coupled to a triple quadrupole mass spectrometer. This method may prove useful for clinical and forensic toxicology laboratories as it allows for automated screening of complex samples for drugs without extraction, separation and sample cleanup. [ABSTRACT FROM AUTHOR]

Human sweat can be collected non-invasively with low infectivity; however, its application as a determination method has been challenged due to the presence of trace amounts of chiral metabolites. Moreover, its application as a biological fluid for disease diagnosis has not been previously reported. In this study, the human dried sweat spot paper (DSSP) method was proposed for the derivatization of a novel mass spectrometric chiral probe, N -[1-Oxo-5-(triphenylphosphonium) pentyl]-(S)-3-aminopyrrolidine (OTPA), determination and resolution of DL-lactic acid (DL-LA) enantiomers in human elbow sweat. The methodological validation revealed the resolution (Rs) as 1.78, the limit of detection (S/N = 3) as 20.83 fmol, good linearity (R2 ≥ 0.9996), and the intra-day and intra-day stability with RSD ranging from 0.53 to 10.85 %, while the average recovery rate of D-LA and L-LA were 104.00 % ± 4.68 % and 107.41 % ± 8.34 %, respectively, with high accuracy. In addition, the method was applied for the determination of DL-LA in the sweat on elbow of 10 healthy volunteers and 30 diabetic patients. The results demonstrated that the D/L ratio and L/D ratio were significantly different (p < 0.0001). In addition, a moderate positive linear correlation between the D/L-LA ratio in human sweat and fasting blood glucose level (r = 0.7744, p < 0.0001) was observed, thereby suggesting that the D/L ratio of lactate in human sweat correlate the glucose level in human fasting blood. The D/L lactate ratio in human sweat could be used as a potential biomarker for diabetes screening. The method can be used to screen for diabetes by providing a dry sweat paper to test equipment and has the potential to be a non-invasive early-warning diagnostic tool for diabetes. [Display omitted] • A dried sweat spot paper method for estimating DL-LA enantiomers in human sweat. • The D/L and L/D ratios of LA in diabetic patient sweat are significantly different. • The D/L-LA ratio in human sweat is positively correlated with fasting blood glucose levels. • DSSP combined with UHPLC-MS/MS accurately quantified D/L-LA ratio is a non-invasive preventive method for screening for diabetes. [ABSTRACT FROM AUTHOR]

This study performs a chemical investigation of blood plasma samples from patients with and without fibromyalgia, combined with some of the symptoms and their levels of intensity used in the diagnosis of this disease. The symptoms evaluated were: visual analogue pain scale (VAS); fibromyalgia impact questionnaire (FIQ); Hamilton anxiety rating scale (HAM); Tampa Scale for Kinesiophobia (TAMPA); quality of life Questionnaire—physical and mental health (QL); and Pain Catastrophizing Scale (CAT). Plasma samples were analyzed by paper spray ionization mass spectrometry (PSI-MS). Spectral data were organized into datasets and related to each of the symptoms measured. The datasets were submitted to multivariate classification using supervised models such as principal component analysis with linear discriminant analysis (PCA-LDA), successive projections algorithm with linear discriminant analysis (SPA-LDA), genetic algorithm with linear discriminant analysis (GA-LDA) and their versions with quadratic discriminant analysis (PCA/SPA/GA-QDA) and support vector machines (PCA/SPA/GA-SVM). These algorithm combinations were performed aiming the best class separation. Good discrimination between the controls and fibromyalgia samples were observed using PCA-LDA, where the spectral data associated with the CAT symptom achieved 100% classification sensitivity, and associated with the VAS symptom achieved 100% classification specificity, with both symptoms at the moderate level of intensity. The spectral variable at 579 m/z was found to be substantially significant for classification according to the PCA loadings. According to the human metabolites database, this variable can be associated with a LysoPC compound, which comprises a class of metabolites already evidenced in other studies for fibromyalgia diagnosis. This study proposed an investigation of spectral data combined with clinical data to compare the classification ability of different datasets. The good classification results obtained confirm this technique is as a good analytical tool for the detection of fibromyalgia, and provides theoretical support for other studies about fibromyalgia diagnosis. [ABSTRACT FROM AUTHOR]

Jabuticaba (Plinia cauliflora) and jambolan (Syzygium cumini) fruits are rich in phenolic compounds with antioxidant properties, mostly concentrated in the peel, pulp, and seeds. Among the techniques for identifying these constituents, paper spray mass spectrometry (PS-MS) stands out as a method of ambient ionization of samples for the direct analysis of raw materials. This study aimed to determine the chemical profiles of the peel, pulp, and seeds of jabuticaba and jambolan fruits, as well as to assess the efficiency of using different solvents (water and methanol) in obtaining metabolite fingerprints of different parts of the fruits. Overall, 63 compounds were tentatively identified in the aqueous and methanolic extracts of jabuticaba and jambolan, 28 being in the positive ionization mode and 35 in the negative ionization mode. Flavonoids (40%), followed by benzoic acid derivatives (13%), fatty acids (13%), carotenoids (6%), phenylpropanoids (6%), and tannins (5%) were the groups of substances found in greater numbers, producing different fingerprints according to the parts of the fruit and the different extracting solvents used. Therefore, compounds present in jabuticaba and jambolan reinforce the nutritional and bioactive potential attributed to these fruits, due to the potentially positive effects performed by these metabolites in human health and nutrition. [ABSTRACT FROM AUTHOR]

In the recent years, the issue of antibiotic residues in food has become an important topic. Most current methods of detecting antibiotics are time-consuming, laborious, and cannot meet the requirements of field testing. In this study, electro-filter paper spray ionization was coupled with a portable linear ion trap mass spectrometer for the rapid determination of four antibiotics (norfloxacin, tetracycline, oxytetracycline, and chlortetracycline) in pork and milk samples. The experimental setup is not only structurally simple but enables analysis of both solid and liquid samples. The samples require only a simple pretreatment and the complete analysis of a sample requires less than 1 min. The linear range for the determination of the four antibiotic standards was from 1 to 100 mg/L (R2≥0.960). The limits of detection (LOD) for the analytes were 0.100 mg/L, with recoveries from 72.4% to 11%. The relative standard deviations (RSDs) were between 2.70% and 16.5%. This study expands the capability for rapid field testing of antibiotics in meat using portable mass spectrometers, which is important for food safety, environmental protection, and criminal investigations. [ABSTRACT FROM AUTHOR]

Furfurals, including 2-furaldehyde, 5-methylfurfural and 5-hydroxymethylfurfural, widely exist in carbohydrate-rich daily foods, and may have toxic effects on humans. Here, a new headspace extraction-paper spray mass spectrometry (HSPS-MS/MS) method was established for furfural detection, in which the extraction and derivatization of volatiles with pre-loaded derivatization agent on paper tips is combined with paper spray mass spectrometry for detection. By this simple and cheap approach, interference of non-volatile matrix compounds is prevented, and the derivatization agent improves electrospray-type ionization efficiency, thus increasing selectivity and sensitivity. The approach was optimized, by investigating positioning during extraction, extraction duration, derivatization agent, addition of internal standard for quantification and finally validated. For this, the developed method was benchmarked against HPLC-UV and could obtain detections limits of 0.32–0.40 μg mL−1 for 2-furaldehyde, 5-methylfurfural and 5-hydroxymethylfurfural in olive oil. Moreover, fast screening of free furfurals in soy sauce, coffees and teas was demonstrated with the HSPS-MS/MS method. [Display omitted] • A simple and inexpensive paper tip was used for headspace extraction and selective furfural enrichment/derivatization. • A paper-based headspace extraction-paper spray mass spectrometry (HSPS-MS/MS) method was established for furfural analysis from olive oil. • The method achieves relevant detection limits of 0.32–0.40 μg mL−1 without any chromatography. • Fast screening of free furfurals in instant drinks was achieved for food quality and safety control. [ABSTRACT FROM AUTHOR]

Paper spray chemical ionization (PSCI) combined with mass spectrometry has been proposed as a sensitive method for the analysis of nonpolar aromatic compounds; however, the mechanism behind PSCI is not well understood. In the present study, the evidence for the occurrence of corona discharge is provided and its mechanism is proposed. Photographs taken with a highly sensitive camera evidently demonstrate the occurrence of corona discharge at the end of the triangular shape tip when a nonpolar solvent such as hexane was used at an applied potential of 6–7 kV. Nevertheless, corona discharge was not observed in the presence of a polar solvent. The occurrence of the corona discharge was attributed to charge accumulation in the dielectric layer generated by the nonpolar solvent on the fibers of the paper tip. Specifically, corona discharge was generated at the tip end when the charge approached a critical threshold. In the presence of a polar solvent, however, the dielectric layer was not generated and, hence, corona discharge was not observed. Based on this information, three nonpolar solvents were selected and their sensitivity for analyzing the phenanthrene and maltene fractions of crude oil was evaluated. Chlorobenzene provided the highest signal abundance; therefore, it was suggested as the optimum solvent for PSCI. Notably, the fundamental understanding of corona discharge in PSCI acquired in this study provides a basis for further improvement of this technique by way of surface modification. [ABSTRACT FROM AUTHOR]

Rationale: Paper spray (PS) is a simple and innovative ambient ionization technique for mass spectrometry (MS) analysis. Under PS‐MS conditions, chemical reactions, which usually occur slowly on a bulk scale, are accelerated. Moreover, the formation of products and transient species can be easily monitored. In this manuscript, reactions between phthalic anhydride and diamines were conducted and monitored using a PS‐MS platform. The reaction products (phthalimides) have many pharmaceutical applications, but their traditional syntheses can take hours under reflux, requiring laborious purification steps. Methods: In situ reactions were performed by dropping methanolic solutions of phthalic anhydride and diamines on a triangular paper. The analyses were achieved by positioning the triangle tip in front of the mass spectrometer entrance, whereas a metal clip was attached to the triangle base. After adding methanol to the paper, a high voltage was applied across the metal clip, and the mass spectra were acquired. Results: The intrinsic reactivity of alkyl and aromatic diamines was evaluated. The carbon chain remarkably influenced the reactivity of aliphatic diamines. For aryl diamines, the ortho isomer was the most reactive. Moreover, for aryl amines with electron‐withdrawing substituents, no reaction was noticed. Conclusions: Taking advantage of the unique characteristics of PS‐MS, it was possible to investigate the intrinsic reactivity of model alkyl (ethylene versus propylene) and aryl (o‐phenylene versus m‐phenylene and p‐phenylene) diamines towards phthalic anhydride. Some crucial parameters that affect the intrinsic reactivity of organic molecules, such as isomerism, intramolecular interaction, and conformation, were easily explored. [ABSTRACT FROM AUTHOR]

We investigated the performance of attenuated total reflectance--Fourier-transform infrared (ATR-FTIR) spectroscopy to rapidly identify intentional additives in a variety of items commonly handled by consumers and workers. We investigated ortho-phthalate esters, specific alternative plasticizers, and flame retardants in food contact materials and consumer products. We also investigated bisphenol A (BPA) and bisphenol S (BPS) developers in thermal paper purchase receipts. Applications include regulatory compliance screening and product deformulation. We compared FTIR results with mass spectrometry measurements. Samples were analyzed either intact or after a simple liquid-phase extraction using small amounts of nonhalogenated solvents. These methods greatly reduced the time and expense of identifying intentionally added phthalates and other plasticizers compared with more sensitive methods. Similarly, BPA and BPS were readily identified in receipts and organophosphorus flame retardants were identified in child car seats. In some samples, FTIR detected novel or unexpected additives not detected by conventional targeted methods. These approaches are useful for screening diverse product samples for intentional additives with a relatively portable instrument while generating very low volumes of spent solvent. [ABSTRACT FROM AUTHOR]

This paper reports the use of paper spray mass spectrometry (PS‐MS) combined with chemometric models to analyze seized samples of anabolic steroids. Because many forensic laboratories typically demand high‐throughput analysis for this type of sample, we developed a quicker and simpler alternative analytical method for routine analysis with minimal sample preparation. Oily samples (n = 39) resulting from seizures carried out by Brazilian Federal and State Police units were selected for this study. These samples were analyzed by PS‐MS in the positive ion mode and full scan (50–1000 m/z), providing spectra containing patterns of the respective active ingredients present in each product. A principal component analysis (PCA) model was built, which discriminated samples mainly according to their active ingredients and allowed to detect and characterize some cases of product counterfeiting. The variable selection method ordered predictors selection was employed jointly with PCA to improve sample cluster separation and to provide model simplification. The final PCA model was built with three principal components and using only 28 spectral variables. This model accounted for 69.82% of the variance and discriminated samples according to their specific active ingredients. [ABSTRACT FROM AUTHOR]

Accurate quantification of blood creatinine is important to estimate the glomerular filtration rate. Existing techniques using liquid chromatography tandem mass spectrometry (LC–MS/MS) have a high accuracy and eliminate most interferences encountered in routine enzymatic and Jaffé methods. However, they require laborious and time-consuming sample treatment and data acquisition. The aim of this study is to develop a fast and simple method to enable a direct analysis of whole blood creatinine with performance measures that are comparable to conventional LC–MS/MS. 5μL whole blood is formed as a three-dimensional spheroid on hydrophobic silanized paper substrates which then undergoes paper-spray ionization—tandem mass spectrometry (PSI–MS/MS). The method is validated using real human samples and compared with LC–MS/MS. PSI–MS/MS whole blood analysis exhibited a lower limit of quantification of 2.5 μg/mL, precision ≤ 6.3%, recovery in the range of 88–94% and excellent linearity (R2 > 0.99; 2.5—20 μg/mL) covering the normal range for creatinine levels. Creatinine levels were comparable to those measured by LC–MS/MS with small deviations of less than 0.3 μg/mL. This simple, fast and accurate microsampling technique for direct analysis of creatinine from whole blood shows promise for routine clinical screening and monitoring. This approach can be readily extended for other analytes of interest and, due to inherent advantages relating to cost, storability, speed, and simplicity, it can be especially advantageous for use in resource-limited settings. [ABSTRACT FROM AUTHOR]

The absolute dating of documents is still one of the most important challenges for forensic document examiners (FDE). The potential difference between the date on a questioned document and the actual year of production of the used paper can be only 1 to 5 years. Until now, there was no analytical method with this accuracy available. This study demonstrates a method for an absolute dating of paper by using the 14C bomb peak and dating the starch in the paper. Accelerator mass spectroscopy (AMS) radiocarbon measurements were performed on starch extracts and cellulose fibers from 50 paper samples with known production year from 1950 to 2018. For most of the paper samples, the measured 14C concentration values in the starch extracts were highly correlated with the data of the 14C bomb peak calibration curve. The differences between the calibrated ages and the actual harvest years of the starch‐containing plants were only up to 3 years. The 14C concentration in the paper fibers showed a lower but significant correlation with the production year of the papers and can be used to support the dating results of the starch extracts. In order to secure the accuracy of the dating, aside from the radiocarbon measurements of the extracted starch other analytical methods or data are used, like a detailed chemical analysis of the paper composition including fiber composition and the spectroscopic analysis of the purity of the starch extracts. In practice, only starch extracts without contaminations are used for the paper dating. [ABSTRACT FROM AUTHOR]

We develop a capillary-paper spray (CPS) ion source which allows for sample separation in the capillary and enables rapid and sensitive paper spray (PS) mass spectrometry (MS) analysis of biofluids. The CPS employs a glass capillary to load liquid analytes, vertically standing at the rear of the PS. To further reduce the matrix effect, a nitrocellulose filter membrane is placed between the glass tube and chromatography paper to absorb proteins and other macromolecules, which is beneficial for the detection of the small molecules. Compared with the normal PS method, the CPS method markedly improves spray stability and prolongs analysis duration, and also generates significantly better signal intensities during the analysis of drugs, thus indicating its potential for clinical use. As a proof of concept, quantitative analysis of drugs (metformin hydrochloride and berberine hydrochloride) in serum is performed. [ABSTRACT FROM AUTHOR]

A direct mass spectrometry method utilizing reactive paper spray ionization was developed for sensitive cannabinoid quantitation in biofluid matrices. The ca. 2-minute sample measurements used on-paper derivatization to significantly increase paper spray mass spectrometry (PS-MS) positive ion mode sensitivity while minimizing sample preparation steps. Calibrations demonstrate high linearity, with R2 > 0.99 for (−)-trans-Δ9-tetrahydrocannabinol (THC) in oral fluid and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) in urine. The limit of detection and lower limit of quantitation were 0.78 and 10 ng mL−1 for THC in oral fluid and 1.3 and 10 ng mL−1 for THC-COOH in urine, respectively. THC-COOH levels measured by reactive PS-MS in seven spiked human urine samples showed bias of −9.4 to 5.9%, and percent difference values of −16.8 to 9.8% in comparison with a reference LC-MS method. Based upon the method simplicity, validation experiments, sensitivity, and rapidity, we conclude that reactive PS-MS has potential applications for rapid cannabinoid drug testing in urine and oral fluid. [ABSTRACT FROM AUTHOR]

This study evaluated the physicochemical characteristics and the production of bioactive compounds of Pereskia aculeata Mill. at different harvest times. Here, we performed a qualitative evaluation of the chemical profile by paper spray mass spectrometry (PSMS), the phenolic acid and flavonoid profile by high-performance liquid chromatography (HPLC), antioxidant activity, total carotenoids, total phenolic compounds, total flavonoids, total anthocyanins, color characteristics, total soluble solids (TSS), total solids (TS), pH, and total titratable acidity (TTA). The chemical profile was not affected, with the exception of 4,5-dimethyl-2,6-octadiene and azelaic acid, which was only identified in the leaves harvested during the winter. The content of four phenolic acids and three flavonoids were analyzed; out of these, no significant amounts of ellagic acid and quercetin were detected. There was no difference in production of bioactive compounds between seasons, reflecting the antioxidant activity, which also did not differ. Brightness, chroma, and leaf pH were the only physicochemical characteristics that did not vary between seasons. [ABSTRACT FROM AUTHOR]

The combination of electrochemistry and mass spectrometry is a powerful analytical tool for studying redox reaction mechanisms and identifying products or intermediates. However, the previously reported devices all require bespoke fabrication and are too complicated to be assembled and used by others. Crucially, the long ion transport distance and small spray volumes make it difficult to capture the short-lived intermediates. We present a practical mass spectrometric method in which surface-modified carbon fiber paper is innovatively applied to detect electrogenerated intermediates. Treating carbon fiber paper with dilute nitric acid removes its surface impurities, enhancing the capability of electro-redox. Electrospray ionization and redox reaction occur simultaneously on the tip of the paper. Transient electro-redox species generate and transfer into gas phase as soon as the appearance of spray. Rapid transport of quantities of electrogenerated ions to the mass spectrometer inlet makes it possible for mass spectrometric identification on the millisecond scale. The short-lived radical cations and iminium ions were successfully captured, reflecting the starting step of the cross-dehydrogenation coupling reaction. The real-time oxidation and online functionalization reactions of tertiary amines were achieved using this device without additional oxidants and electrolytes. In this way we could achieve in-depth mechanistic understanding and rapid screening of serial reactions. [Display omitted] • Treating carbon fiber paper with dilute nitric acid enhances the capability of detecting electrogenerated intermediates. • A-CFPSI permits the real-time monitoring of electrochemical reaction intermediates on the millisecond scale. • No additional electrolytes and oxidants are required, avoiding interference with the mass spectrum. • A-CFPRSI can be used for rapid screening of electrochemical reactions and mechanism researches. [ABSTRACT FROM AUTHOR]

[Display omitted] • PVC-diphenylamine modified cellulose was proposed as sorptive phase. • The synthesis, using the dip-coating technique, is simple and cost-effective. • Opioids interact with the membrane by a mixed-mode interaction. • Direct infusion mass spectrometry allows to reduce the time of analysis. • The approach was successfully applied to real saliva samples containing codeine and tramadol. This article evaluates the potential of cellulose paper as a substrate for preparing a polyvinylchloride (PVC)-diphenylamine sorptive phase that can be used under the thin film microextraction (TFME) format. This phase was easily synthesized using the dip-coating technique to coat the filter paper with PVC, followed by the covalent bonding of diphenylamine. As a result, aromatics rings are available on paper surface to isolate the target analytes by a mixed-mode interaction at physiological pH. The resulting material was characterized by infrared spectroscopy, UV–Vis diffuse reflection spectroscopy, and scanning electron microscopy. As analytical problem, three opioids (methadone, codeine, and tramadol) were determined in saliva samples by direct infusion mass spectrometry. Different variables involved in the extraction procedure have been optimized (e.g. sample pH, extraction time, and sample dilution). The proposed method provides good linearity (R2 > 0.9817) and sensitivity (detection limits in the range from 1.5 µg L−1 to 15 µg L−1). The intra-day and inter-day precision, expressed as relative standard deviation, were better than 16.4 % and 18.5 % respectively. The accuracy, expressed as relative recovery, provides values in the interval from 82 % to 105 %. Finally, the proposed approach has been successfully applied to real saliva samples of patients under codeine and tramadol medical prescription. [ABSTRACT FROM AUTHOR]

In this work, we synthesized diethylamino substituted pyrazolo imine (3) fluorescent probe for recognition of Hg2+ion.The sensor probe 3 can detect Hg2+ by colorimetric method, and there is a 10‐fold enhancement in fluorescence response. When the fluorescent probe bound with Hg2+ ion, turn‐on fluorescence was observed via the coordination. Probe 3 has an excellent selectivity toward Hg2+ in the CH3CN/H2O (8:2, v/v) solution with low limit of detection and high binding association constant of 551 parts per billion (ppb) and 6.6067 × 106 m−1 for 3+Hg2+, respectively. Furthermore, the formation of 3+Hg2+ complex with 1:1 binding mode was evidenced by Job's plot, 1H NMR spectroscopy and Mass analysis. In addition, probe 3 is a feasible option to detect Hg2+ in various sources of water samples. Bio‐imaging experiments have demonstrated that probe 3 can be used to monitor Hg2+ in Escherichia coli bacterial cell. The sensor 3 was also used for paper strip application to detect Hg2+ ion. [ABSTRACT FROM AUTHOR]

Accurate quantification of disease‐signature microRNAs (miRNAs) in biomedical samples is in high demand for clinical diagnosis but still challenging because of the low abundance of miRNAs and complicating interferences in the milieus. Here, we report a multi‐amplification strategy based on paper‐spray mass spectrometry (PS MS) for the analysis of miRNAs in blood. A toehold‐mediated DNA‐strand‐displacement reaction (TSD) is employed to amplify the signal chain and to ensure the specificity. The signal chain is then cleaved by UV light to release signal molecules for detection. Moreover, the paper spray method can efficiently filter out interfering substances in the blood and further enhance the sensitivity of detection. This concept is successfully demonstrated in the prototypical detection of the cancer biomarker miRNA‐141 in blood and serum. The proposed TSD‐PS MS approach provides an efficient method for the sensitive detection of oligonucleotides at low concentration in complicated milieus. [ABSTRACT FROM AUTHOR]

Accurate quantification of disease‐signature microRNAs (miRNAs) in biomedical samples is in high demand for clinical diagnosis but still challenging because of the low abundance of miRNAs and complicating interferences in the milieus. Here, we report a multi‐amplification strategy based on paper‐spray mass spectrometry (PS MS) for the analysis of miRNAs in blood. A toehold‐mediated DNA‐strand‐displacement reaction (TSD) is employed to amplify the signal chain and to ensure the specificity. The signal chain is then cleaved by UV light to release signal molecules for detection. Moreover, the paper spray method can efficiently filter out interfering substances in the blood and further enhance the sensitivity of detection. This concept is successfully demonstrated in the prototypical detection of the cancer biomarker miRNA‐141 in blood and serum. The proposed TSD‐PS MS approach provides an efficient method for the sensitive detection of oligonucleotides at low concentration in complicated milieus. [ABSTRACT FROM AUTHOR]

Introduction: Drug checking services for harm reduction and overdose prevention have been implemented in many jurisdictions as a public health intervention in response to the opioid overdose crisis. This study demonstrates the first on‐site use of paper spray mass spectrometry for quantitative drug checking to address the limitations of current on‐site drug testing technologies. Methods: Paper spray mass spectrometry was used to provide on‐site drug checking services at a supervised consumption site in the Downtown Eastside of Vancouver, British Columbia, Canada during a 2‐day pilot test in August 2019. The method included the targeted quantitative measurement of 49 drugs and an untargeted full scan to assist in identifying unknown/unexpected components. Results: During the pilot, 113 samples were submitted for analysis, with 88 (78%) containing the client expected substance. Fentanyl was detected in 45 of 59 expected fentanyl samples, and in 50 (44%) samples overall at a median concentration of 3.6% (w/w%). The synthetic precursor of fentanyl, 4‐anilino‐N‐phenethyl‐piperidine (4‐ANPP), was found in 74.0% of all fentanyl samples at a median concentration of 2.2%, suggesting widespread poor manufacturing practices. Etizolam was detected in 10 submitted samples anticipated to be fentanyl at a median concentration of 2.5%. No clients submitting these samples expected etizolam or a benzodiazepine in their sample. In three instances, it was co‐measured with fentanyl, and in seven cases it was detected alone. Discussion and Conclusions: The quantitative capabilities and low detection limits demonstrated by paper spray mass spectrometry offer distinct benefits over existing on‐site drug checking methods and harm reduction services. [ABSTRACT FROM AUTHOR]

Traditional PFAS analysis by mass spectrometry (MS) is time-consuming, as laborious sample preparation (e.g., extraction and desalting) is necessary. Herein, we report fast detection of PFAS by paper spray (PS)-based MS techniques, which employs a triangular-shaped filter paper for sample loading and ionization (≤ 3 min per sample). In this study, PS-MS was first used for direct PFAS analysis of drinking water, tap water, and wastewater. Interestingly, food package paper materials can be directly cut and examined with PS-MS for possible PFAS contamination. For samples containing salt matrices which would suppress PFAS ion signal, desalting paper spray mass spectrometry (DPS-MS), was shown to be capable of rapidly desalting, ionizing and detecting PFAS species such as per-fluorooctanoic acid (PFOA) and per-fluorosulphonic acid (PFOS). The retention of PFAS on paper substrate while salts being washed away by water is likely due to hydrophilic interaction between the PFAS polar head (e.g., carboxylic acid, sulfonic acid) with the polar filter paper cellulose surface. The DPS-MS method is highly sensitive (limits of detection:1.2–4.5 ppt) and can be applicable for directly analyzing soil extract and soil samples. These results suggest the high potential of PS-MS and the related DPS-MS technique in real-world environmental analysis of PFAS. [Display omitted] • Developed a simple, inexpensive, sensitive and rapid PFAS detection based on PS-MS and DPS-MS. • Food packaging paper can be cut and directly analyzed for PFAS contamination by PS-MS in less than 1 min. • Soil sample in a small amount can be directly analyzed by DPS-MS for PFAS identification, with no sample preparation. [ABSTRACT FROM AUTHOR]

A procedure for the rapid simultaneous determination of anthraquinone and bisphenol A in paper and cardboard is proposed based on a combination of extraction with subcritical methanol and subsequent analysis of the extracts by HPLC‒tandem mass spectrometry. The achieved limits of detection are 25 and 250 µg/kg for anthraquinone and bisphenol A, respectively, and fully meet present-day safety requirements for pulp and paper products. The total duration of the analysis, including sample preparation, is not more than 45 min. The sensitivity of anthraquinone determination is 1‒2 orders of magnitude higher than that of the known procedures, including those with the preconcentration of analytes. The results obtained were successfully used to study paper and cardboard samples, in most of which unacceptably high levels of the anthraquinone concentration were found. [ABSTRACT FROM AUTHOR]

A novel chemically modified cellulose filter paper (CMCFP) was prepared by a two-step reaction of esterification and thiol-ene click reaction with cellulose filter paper (CFP). The paper based CMCFP extraction material was used to extract amphetamine-type stimulants (ATSs) from water, followed by high-performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-MS/MS) determination. The FT-IR, XPS, and SEM characterizations showed that the modifiers of 3-mercaptopropionic acid and sodium 4-vinylbenzenesulfonate were successfully covalently grafted onto the CFP. The recovery rates of the 7 target ATSs by CMCFP extraction had a maximum value in the pH range of 4.0–7.0. The kinetic experiments indicated that the main adsorption mechanism of CMCFP for ATSs was chemisorption. The adsorption capacity was greater than 37 ng·cm-2. Surface water and wastewater spike experiments revealed that the determination of 7 ATSs by CMCFP extraction coupled with HPLC-MS/MS method had recoveries of 80.5–116%. Meanwhile, the detection limits were 0.40–3.03 ng·L-1, and the linear range was 20–1000 ng·L-1 with relative standard deviations of 2.2–11%. The CMCFP extraction material obtained in this study is environmentally friendly and economical, and has the same good extraction efficiency as the commercial solid phase extraction cartridges. [Display omitted] • A novel chemically modified cellulose filter paper (CMCFP) was prepared. • The CMCFP was used to extract amphetamine-type stimulants (ATSs) from water. • Determination of ATSs in water was established by CMCFP extraction with HPLC-MS/MS. [ABSTRACT FROM AUTHOR]

A bifunctional fluorescence probe (PCT) based on 2‐Hydroxy‐1‐naphthaldehyde and thiosemicarbazide was developed. The probe PCT can selectively detect Ag+ and Al3+ with two clear fluorescence color changes from colorless to yellow and blue violet, respectively. According to the Job's plots and mass spectrum, the binding stoichiometry of the probe PCT with Ag+ and Al3+ was 1 : 1, respectively. Moreover, the detection limit values of PCT for Ag+ and Al3+ in neutral solutions were 1.97 and 1.63 nM and these values were remarkably lower than allowed Ag+ and Al3+ concentrations in potable water determined by the World Health Organization (WHO). The distinct different binding mode were elucidated in this paper. Finally, the probe PCT has been used successfully for the detection of Ag+ and Al3+ in real water samples, logic gate and test paper. [ABSTRACT FROM AUTHOR]

Tobacco smoke contains a large number of harmful substances and has been widely proved to be able to induce a variety of human diseases. Human eyes are exposed to ambient air for a long time in daily life and are susceptible to air pollutants such as tobacco smoke in the air. Therefore, direct monitoring of characteristic components of tobacco smoke in human tears is expected to efficiently assess the exposure level of tobacco smoke to human eyes. Due to human tears at the microliter level, conventional sample collection and chemical analysis methods are a challenging task. Mass spectrometry (MS) has the unique advantages of high sensitivity, specificity and speed, especially, the development of ambient MS with solid substrates has greatly facilitated direct sample analysis with little or no sample pretreatment. Schirmer paper strip is clinically used for sampling of human tears, which is safe, non-invasive, and can be used for measuring the volume of tears. In this study, a small Schirmer paper strip was further prepared for noninvasive microsampling of human tears which exposed to tobacco smoke, and high voltage and an organic solvent were applied onto Schirmer paper to directly generate paper spray ionization for ambient MS analysis. The good analytical performances, including sensitivity (LOD: 0.1 μg/L, S/N≥3; LOQ: 1.0 μg/L, S/N≥10), precision (RSD: 4.89%-7.61%, n=5, with internal standard), recovery (98%-102.1%, n=5), and linear range (0.5-50 μg/L, R2=0.991 8) were achieved. Monitoring nicotine in human tears under different exposure times was also investigated, showing that the concentration of nicotine will the increase with increasing the exposure time ranging from 0 to 8 min. The nicotine can research to be 45 μg/L after burning a cigarette (about 8 min). The retention time of nicotine in human tears was found to be about 20 min (less than 5%), and the half-life time is about 4 min. Overall, our results show that Schirmer paper spray mass spectrometry could be used for qualitative and quantitative detection of trace environmental exposures such as nicotine in human eyes with many advantages, including safe, noninvasive, easy-to-operation, low-consumption as low as 1.0 μL, and thus has potential for many applications in environmental exposure and human health. [ABSTRACT FROM AUTHOR]