Liquid Chromatography-atmospheric Pressure Chemical Ionization Research Articles

Determination of Patulin in Apple Juice and Apple-Derived Products Using a Robotic Sample Preparation System and LC-APCI-MS/MS.

Patulin, a toxic mycotoxin, can contaminate apple-derived products. The FDA has established an action level of 50 ppb (ng/g) for patulin in apple juice and apple juice products. To effectively monitor this mycotoxin, there is a need for adequate analytical methods that can reliably and efficiently determine patulin levels. In this work, we developed an automated sample preparation workflow followed by liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI-MS/MS) detection to identify and quantify patulin in a single method, further expanding testing capabilities for monitoring patulin in foods compared to traditional optical methods. Using a robotic sample preparation system, apple juice, apple cider, apple puree, apple-based baby food, applesauce, fruit rolls, and fruit jam were fortified with 13C-patulin and extracted using dichloromethane (DCM) without human intervention, followed by an LC-APCI-MS/MS analysis in negative ionization mode. The method achieved a limit of quantification of 4.0 ng/g and linearity ranging from 2 to 1000 ng/mL (r2 > 0.99). Quantitation was performed with isotope dilution using 13C-patulin as an internal standard and solvent calibration standards. Average recoveries (relative standard deviations, RSD%) in seven spike matrices were 95% (9%) at 10 ng/g, 110% (5%) at 50 ng/g, 101% (7%) at 200 ng/g, and 104% (4%) at 1000 ng/g (n = 28). The ranges of within-matrix and between-matrix variability (RSD) were 3-8% and 4-9%, respectively. In incurred samples, the identity of patulin was further confirmed with a comparison of the information-dependent acquisition-enhanced product ion (IDA-EPI) MS/MS spectra to a reference standard. The metrological traceability of the patulin measurements in an incurred apple cider (21.1 ± 8.0 µg/g) and apple juice concentrate (56.6 ± 15.6 µg/g) was established using a certified reference material and calibration data to demonstrate data confidence intervals (k = 2, 95% confidence interval).

Determination of vitamin K encapsulated into lipid nanocarriers by dispersive liquid-liquid microextraction combined with liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

Dispersive liquid-liquid microextraction was used in conjunction with liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry to quantitate vitamins K1 and K2 in vitamin-fortified emulsions, and vital microextraction parameters were optimized using response surface methodology coupled with Box-Behnken design. Under optimal microextraction conditions, highly linear (R 2 > .999) calibration curves were obtained for both vitamins in a broad concentration range (1-1000 μg/L), and vitamin recoveries exceeded 90%. The detection and quantitation limits equaled 1.89 and 5.72 μg/L for vitamin K1, respectively, and 5.00 and 15.15 μg/L for vitamin K2, respectively. When applied to vitamin-K-loaded nanoemulsions and solid lipid nanoparticles, the developed method achieved excellent results, outperforming the currently employed Korean Food Code method, and therefore holding great promise for the quantitation of vitamin K in vitamin-fortified food products.

Determination and enantioselective separation of zilpaterol in human urine after mimicking consumption of contaminated meat using high-performance liquid chromatography with tandem mass spectrometry techniques.

The synthetic β-adrenoreceptor agonist zilpaterol is legitimately used as an animal feed supplement in selected countries due to its known effects on lipolysis and protein biosynthesis. These pharmacological characteristics of zilpaterol have contributed to its classification as doping agent in sport by the World Anti-Doping Agency. However, the use as a feed supplement can lead to residues of the drug in edible tissues and, possibly, also in the urine of consumers. To provide urinary elimination profiles of microdosed zilpaterol and to determine whether the ingestion of zilpaterol below or at the acceptable daily intake level of 0.04 μg/kg bodyweight can result in an adverse analytical finding (AAF) in doping controls, healthy volunteers were administered single or multiple oral doses of 0.5μg or 3μg zilpaterol to mimic ingestion of contaminated cattle meat. Urine samples were collected and analyzed using a validated high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method and a newly developed chiral high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (HPLC-APCI-MS/MS) method. Urinary peak concentrations of zilpaterol were observed for all volunteers 1.5-12.5h after ingestion, and maximum levels >5ng/mL, which would constitute an AAF in doping controls, were found after the intake of 3μg of zilpaterol on five consecutive days in one out of five study participants. Noteworthy, the enantiomeric ratio of excreted zilpaterol remained constant over time. This study provides first insights into the urinary excretion of microdosed zilpaterol. Furthermore, a method was successfully developed and applied for the separation of the zilpaterol enantiomers with mass spectrometric detection.

Qualitative Determination of Polysulfide Species in a Lithium-Sulfur Battery by HR-LC-APCI-MSn with One-Step Derivatization.

Lithium-Sulfur (Li-S) batteries are one of the most promising next-generation batteries due to their ultrahigh energy density up to 500 W h kg-1. However, despite the steady progress during the last several decades, there have been significant challenges for practical applications and commercialization. One of the major issues is controlling the lithium polysulfide (LiPS) shuttling process, which causes premature cell failure. To better understand the mechanism of the LiPS shuttling chemistry, a qualitative and quantitative analysis on polysulfide species in Li-S cell has profound significance for realizing highly efficient sulfur electrochemistry. Here we report a qualitative determination of the derivatized polysulfides in the electrolyte of a custom-made Li-S pouch cell with a high-resolution liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry method for the first time. The ionization efficiency of the methylated polysulfides was affected by the tune parameters such as the corona discharge current, the vaporizer temperature, and the source capillary temperature. It was found that the source capillary temperature was the dominant parameter to increase the peak intensity of CH3S7- ion, which was the smallest peak in the spectrum. An unusual and unique ionization pattern for methylated polysulfides detected in atmospheric pressure chemical ionization negative mode was elucidated by using first-principles calculations.

Rapid Quantification of Endogenous Steroids in Human Serum Using Leidenfrost Effect-Assisted Thermal Desorption Atmospheric Pressure Photoionization Orbitrap Mass Spectrometry.

Unconjugated sex steroids in human serum play a crucial role in physiological and pathological studies and are frequently considered as biomarkers in clinical diagnosis. Because of their low polarity, poor volatility, and low concentration, the rapid and highly sensitive analysis of sex steroids in real serum matrix by ambient mass spectrometry is still challenging. Here, Leidenfrost effect-assisted thermal desorption atmospheric pressure photoionization orbitrap mass spectrometry (LETD-APPI-MS) was developed and applied to quantify free sex steroids in human serum without derivatization and chromatography separation within a few minutes. The concentration of target analyte could be increased by approximately two orders during the LETD process. The limit of quantifications and detections of endogenous sex steroids in human serum were measured at the ppt level. In contrast with commonly used immunoassays in clinical laboratories, LETD-APPI-MS enables the accurate measurements of multiple free sex steroids without the interference of cross-reactions. The endogenous sex steroids of 38 female serums at four physiological stages during pregnancy were rapidly tested by LETD-APPI-MS, whose results were highly consistent with that using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS), indicating LETD-APPI-MS has a strong clinical application potential in steroid analysis.

Development, validation, and estimation of measurement uncertainty for the quantitative determination of nitrosamines in Sartan drugs using liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry

In the current study, a feasible and sensitive liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI-MS/MS) method was developed and validated for the determination of eight nitrosamines in Sartan active pharmaceutical ingredients (APIs). The proposed LC-APCI-MS/MS method was validated as per regulatory guidelines. The limit of detection and limit of quantification was found to be in the range of 0.32–1.58 ng/mL, 1.09–4.74 ng/mL, and the recovery was in the range of 86.4–109.6% for Sartan APIs, and 82.1–114.1% for Sartan final products, respectively. The calibration curves of all nitrosamines in the concentration range of 2–100 ng/mL were carried out, and the coefficient of determination (R2) was found to be in the range of 0.9990–0.9999. The robustness of the present method was within the acceptance (<15% RSD) for system suitability. The measurement uncertainty was determined for this method, and the expanded uncertainty was found to be in the range of 16.3–25.9% for Sartan APIs and 8.41–15.6% for Sartan drug products. The precision and recovery were found to be major sources which can induce the uncertainty during the measurement of nitrosamines in Sartan API and Drug products with the developed and validated method.

Novel QuEChERS-ultra-performance liquid chromatography–atmospheric-pressure chemical ionization tandem mass spectrometry method for the simultaneous determination of vitamin D and vitamin K in vitamin-fortified nanoemulsions

Nanoemulsion is a new vehicle for food fortification. In this study, a simple and reliable method for the simultaneous analysis of vitamins D2, D3, K1, and K2 in vitamin-fortified nanoemulsions was developed using QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction and ultra-high performance liquid chromatography–atmospheric-pressure chemical ionization tandem mass spectrometry techniques. Response surface methodology was employed to optimize the extraction parameters. The method was validated for the vitamins in terms of LOD (0.03–0.25 μg/L), LOQ (0.10–0.77 μg/L), intra-day (≤4.50%), inter-day precisions (≤6.43%), and accuracy (98.5%–108.0%). The recoveries of the vitamin-fortified nanoemulsion and yogurt were in the ranges of 104.0%–109.2% and 73.3%–85.2%, respectively. The solvent consumption and analysis time were reduced by 5.6 and 3.3 folds, respectively, rendering it superior to the traditional extraction methods established by the Association of Official Analytical Chemists and the Ministry of Food and Drug Safety.

Analysis of 14 endocannabinoids and endocannabinoid congeners in human plasma using column switching high-performance atmospheric pressure chemical ionization liquid chromatography-mass spectrometry.

The endocannabinoid system (ECS) is a complex cell-signaling system. To address the growing need of analytics capturing endocannabinoid levels to investigate the ECS, we developed and validated an assay for the quantitative analysis of 14 endocannabinoids and congeners. A simple extraction using protein precipitation with acetonitrile followed by online-trapping high-performance liquid chromatography-tandem mass spectrometry (LC/LC-MS/MS) was used to monitor the levels of 14 endocannabinoids in plasma. The assay was validated and intra-run and inter-run accuracies and imprecisions as well as matrix effects, recoveries, and sample stabilities were determined. As a proof of concept, a subset of study samples after naturalistic administration of Cannabis flower and concentrate was analyzed. With the exception of N-oleoyl dopamine and oleamide, all endocannabinoids fulfilled the predefined acceptance criteria. Reproducible recoveries and no significant matrix effects were observed. Sample stability was an issue. Analysis of the proof-of-concept study samples revealed a significantly (p = 0.006) higher concentration of docosatetraenoyl ethanolamide in concentrate users (300 ± 13pg/mL) compared to flower users (252 ± 11pg/mL). A robust, sensitive high-throughput assay for the quantitation of 14 endocannabinoids and congeners was successfully validated. Our study showed that it is mandatory to (A) appropriately stabilize samples and (B) separate and separately quantify 1-AG and 2-AG; otherwise, study results are unreliable. The analysis of study samples from Cannabis flower users versus Cannabis concentrate users revealed higher levels of docosatetraenoyl ethanolamide and anandamide (n.s.) in high THC concentrate users in accordance with the existing literature, supporting the validity of the assay measurements. Graphical abstract.

Contrastive analysis of lipid composition and thermal and crystallization behavior of olein/stearin fractionated by novel layer melt crystallization from palm oil.

Melt crystallization is typically recognized as a highly efficient and green method for oil fractionation. This work concentrated on novel layer melt crystallization for preparing desirable olein and stearin products from palm oil and the evaluation of fraction quality. Layer melt crystallization was performed at various temperatures and the effects on fractions were evaluated using iodine value (IV), solid fat content (SFC) and melting point. The lipid composition, thermal and crystallization properties, and phase behaviors of the final optimized fractions were determined using gas chromatography, high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry and differential scanning calorimetry. Increasing crystallization tube temperatures under the same jacket temperature increased the melting point and SFC, while decreasing the IV of the olein product. Opposite results were observed for the stearin product. Major fatty acids in fractions were determined as palmitic acid and oleic acid. 1,2-Dioleoyl-3-palmitoylglycerol and 1,3-dipalmitoyl-2-oleoylglycerol were identified as the main triacylglycerols in olein and stearin fractions, respectively. A critical effect of crystallization temperature on co-crystallization of oleins and stearins was revealed. A transition from plate-like crystal growth to spherulitic growth with spontaneous nucleation was indicated in palm oil and stearin fractions with increasing crystallization temperature. As for olein fractions, a temperature increase resulted in heterogeneous nucleation from instantaneous nucleation. Novel layer melt crystallization was successfully applied and optimized for fractionating palm oil. The composition and property changes of obtained fractions were analyzed and explained at both macroscopic and microscopic levels. © 2021 Society of Chemical Industry.

Neuroprotective Effect of Alkylresorcinols from Wheat Bran in HT22 Cells: Correlation with in vitro Antioxidant Activity

Alkylresorcinols (ARs), which are phenolic lipids found in wheat bran, have attracted a considerable amount of attention because of their antioxidant properties. However, the mechanism of ARs for regulating neuroprotective activity remains unclear. The correlation between the cellular neuroprotective effects of ARs in HT22 cells and their in vitro antioxidant activity were investigated. The results showed that two main constituents of crude ARs were C19:0 and C21:0, which was identified by high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry. Pre-treatment with 400 μg/mL crude ARs could protect from H2O2-induced cellular damage involving low cell viability, leakage of lactate dehydrogenase and decreased superoxide dismutase activity. The maximum radical scavenging ability of DPPH•, ABTS•+, • and •OH– was 85.45%, 88.89%, 84.42% and 87.36%. The neuroprotection effect of ARs was significantly correlated with in vitro antioxidant capacity, confirmed by the maximum correlation coefficients being 0.9988, –0.9974 and 0.9972. The antioxidation of ARs potentially promoted neuroprotective effect and further study is needed to clarify the other mechanism behind ARs benefits.

Determination of propofol in human plasma with C18 pipette-tip based solid-phase extraction followed by liquid chromatography atmospheric-pressure chemical ionization tandem mass spectrometry analysis

Propofol is a widely used intravenous anesthetic for sedation during the surgery and worldwide propofol abuse has been frequently reported also. As an essential procedure for sample pretreatment, solid-phase extraction (SPE) is generally time-consuming and labor-intensive, which hindered the further improvement in the analysis of propofol from biological fluids. In this study, a rapid C18 pipette-tip based SPE method was developed to pretreat human plasma samples directly, bypassing the need for protein precipitation. The experiment conditions were optimized for the best extraction recovery (23.6 ± 4.1 %). After pretreatment, the plasma propofol was determined with liquid chromatography atmospheric-pressure chemical ionization-tandem mass spectrometry (LC-APCI-MS/MS) using propofol-d17 as the internal standard. The quantification method showed good linearity in the range of 0.005–5 μg mL−1 (r2 = 0.9992). The sensitivity, specificity, accuracy (90.0–113.3 %), precision (2.0–8.9 %), and stability (95.6–102.1 %) were satisfied for bioanalytical analysis. Finally, the concentrations of propofol in the plasma of a patient under anesthesia were determined with the proposed method and compared with the theoretical concentrations calculated with a population pharmacokinetics (popPK) model. In general, this work provided a rapid and straightforward method for the study of propofol in pharmacokinetics and forensic science.

A simplified and sensitive LC-APCI-MS/MS method for the quantification of propofol: Application to a bioequivalence study in healthy Chinese subjects

Propofol has become the preferred anesthetic in recent years due to its desirable pharmacologic properties. However, propofol possesses a very narrow therapeutic window between the favorable clinical effect and potentially lethal toxicity, therefore, a rapid, simplified, and sensitive liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI-MS/MS) method is presented in this study for the quantification of propofol in human plasma using the isotope-labeled internal standard (IS) of propofol-d17, and then applied in a bioequivalence study. Sample preparation was accomplished through simple one-step precipitation of plasma protein with acetonitrile. Chromatographic separation was acquired on an ACE Excel 3 Super C18 column (2.1 × 50 mm, 3µm) using gradient elution at a flow rate of 0.5mL/min. The MS detection was achieved in the negative ion APCI by multiple reaction monitoring (MRM) mode using the transitions of m/z 177.2 → 161.0 for propofol and m/z 194.2 → 174.2 for IS, respectively. 30 healthy Chinese subjects were enrolled in the open-label, randomized, two-period, two-sequence, cross-over bioequivalence study after single-dose intravenous administration of propofol medium-chain triglyceride and long-chain triglyceride (MCT/LCT). The current method was precise and accurate at a linearity range of 4.00-1,000ng/mL without severe interference from the plasma matrix. The inter- and intra-batch precision (2.3 to 15.8%) and accuracy (-4.4 to 3.0%), IS-normalized matrix effect (coefficient of variation ≤4.6%), extraction recovery (107.1-117.1%), stability (coefficient of variation ≤8.0%), and dilution integrity were all within the acceptable range. The 90% confidence intervals (CIs) of the ratios of the geometric means (test/reference) were 86.44-104.88% for Cmax, 96.30-104.52% for AUC0-t, and 96.56-105.05% for AUC0-∞, which were all within the predefined bioequivalence range of 80-125%. Besides, both propofol MCT/LCT preparations were well tolerated in healthy Chinese subjects, and there were no serious adverse events during the study. The method is more simplified and sensitive than the previously reported modes of propofol detection. The two propofol MCT/LCT preparations were considered to be bioequivalent.

Determination of acrylamide in coffee by ultra performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry

A method using ultra high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (UHPLC-APCI-MS/MS) was developed for the determination of acrylamide in coffee. The coffee samples spiked with 13C3-acrylamide as the internal standard were extracted with methanol, and cleaned using HLB solid phase extraction (SPE) cartridges. The liquid chromatography separation was performed on a Brownlee validated AQ C18 column with isocratic elution. Methanol and 0.1% (volume percentage) formic acid aqueous solution were used as the mobile phase. Identification of acrylamide was achieved by APCI-MS/MS with multiple reaction monitoring (MRM) in the positive mode. The quantification analysis was performed by the internal standard method. The calibration curve showed good linearity with a correlation coefficient of 0.999 in the range of 0.5-100.0 μg/L. The limit of detection (LOD) was 5.0 μg/kg. The limit of quantification (LOQ) was 10.0 μg/kg. Recovery of acrylamide from coffee sample was evaluated at concentrations of 100.0, 200.0 and 1000.0 μg/kg. The average recoveries of acrylamide were between 94.6%-115.0% with relative standard derivations (RSDs) in the range of 2.8%-3.6% (n=6). This simple, accurate and sensitive method was proven to be suitable for the determination of acrylamide in coffee.

Oxidation evaluation of free astaxanthin and astaxanthin esters in Pacific white shrimp during iced storage and frozen storage.

In this paper, the changes in free astaxanthin (F-AST) and astaxanthin esters (AST-Es) in Litopenaeus vannamei during iced storage and frozen storage were investigated. The liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry method was used to quantify the molecular species of AST-Es in shrimp during storage. Based on the analysis of autoxidation products, apo-12-astaxanthinal and apo-13-astaxanthinone docosahexaenoic acid (DHA) ester were identified as the major oxidation products of F-AST and AST-Es in L. vannamei during storage. The total astaxanthin (T-AST) content decreased by 34.51% after 7 days in iced storage. In contrast, the content of T-AST decreased by 43.76% after 12 weeks in frozen storage. The content of F-AST decreased by 29.99% while 13-cis-astaxanthin increased after 3 days in iced storage, which indicated that degradation of AST was accompanied by isomerization. Total volatile basic nitrogen and T-AST content showed a significant negative correlation while in frozen storage, where the concentration of T-AST might be one indicator to evaluate shrimp freshness. The correlation coefficients between phenol oxidase, lipoxygenase, apo-12-astaxanthinal, and apo-13-astaxanthinone DHA ester were all greater than 0.97 (P < 0.01). This correlation indicates that phenol oxidase and lipoxygenase were the main internal factors to improve oxygenation of astaxanthin in L. vannamei. These results provide a theoretical basis for further study of oxidation and the degradation mechanism in astaxanthin, as well as a new idea for the development and utilization of astaxanthin compounds in Pacific white shrimp. © 2018 Society of Chemical Industry.

Determination of vitamin K composition of fermented food

A rapid ultra-high performance liquid chromatography–atmospheric pressure chemical ionization tandem mass spectrometric (UHPLC-APCI-MS/MS) method was developed for the analysis of vitamin K compounds: phylloquinone (PK) and menaquinones (MK-n). Non-chlorinated mobile phase composition was optimized for separation of eight vitamin K compounds on a reversed phase column in 10 min. Sample treatment with liquid and solid phase extractions and by the use of MK-4 as an internal standard enabled the quantitation of microgram level of vitamin K compounds in food. The method was used to screen and quantitate vitamin K from 17 fermented food products. The highest amount of PK was detected in kimchi (42 µg/100 g), whereas the highest MK-7 content was detected in natto (902 µg/100 g). Some MK-9 was present in kefir (5 µg/100 g). Two Chinese fermented soybean pastes contained significant amount of MK-6 (5–36 µg/100 g), MK-7 (12–86 µg/100 g), and MK-8 (22–44 µg/100 g).

Sebomic identification of sex- and ethnicity-specific variations in residual skin surface components (RSSC) for bio-monitoring or forensic applications

Background“Residual skin surface components” (RSSC) is the collective term used for the superficial layer of sebum, residue of sweat, small quantities of intercellular lipids and components of natural moisturising factor present on the skin surface. Potential applications of RSSC include use as a sampling matrix for identifying biomarkers of disease, environmental exposure monitoring, and forensics (retrospective identification of exposure to toxic chemicals). However, it is essential to first define the composition of “normal” RSSC. Therefore, the aim of the current study was to characterise RSSC to determine commonalities and differences in RSSC composition in relation to sex and ethnicity.MethodsSamples of RSSC were acquired from volunteers using a previously validated method and analysed by high-pressure liquid chromatography–atmospheric pressure chemical ionisation–mass spectrometry (HPLC-APCI-MS). The resulting data underwent sebomic analysis.ResultsThe composition and abundance of RSSC components varied according to sex and ethnicity. The normalised abundance of free fatty acids, wax esters, diglycerides and triglycerides was significantly higher in males than females. Ethnicity-specific differences were observed in free fatty acids and a diglyceride.ConclusionsThe HPLC-APCI-MS method developed in this study was successfully used to analyse the normal composition of RSSC. Compositional differences in the RSSC can be attributed to sex and ethnicity and may reflect underlying factors such as diet, hormonal levels and enzyme expression.

Bioavailability of wilforlide A in mice and its concentration determination using an HPLC-APCI-MS/MS method

Wilforlide A (WA), an active compound in Tripterygium wilfordii Hook F (TW) which is a traditional Chinese medicine for treatment of autoimmune diseases, is a quality control marker for TW product. At present, the bioavailability/pharmacokinetics of WA is not known. Such information is not only essential to evaluate the relevance of WA as a quality control maker, but also important for future clinical efficacy studies. Therefore, a high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometric method (HPLC-APCI-MS/MS) was developed and applied to a bioavailability/pharmacokinetic study of WA.WA and celastrol (the internal standard, IS) were extracted by a liquid-liquid extraction method using methyl tert-butyl ether. Multiple reaction monitoring (MRM) scanning in positive ionization mode was used to monitor the transition of m/z 455.1 to 191.3 for WA and 451.3 to 201.2 for IS. This method was validated and applied to a pharmacokinetic study of WA in mice following intravenous administration (IV, 1.2 mg/kg), intraperitoneal injection (IP, 6 mg/kg) and oral administration (PO, 30 mg/kg).The lower limit of quantification (LLOQ) for WA was 10 ng/ml. The intra- and inter-day precision was found to be within 15.4% while the accuracy within 94.1–115.7% for all the quality control and LLOQ samples. The samples were stable under all the usual storage and experimental conditions. The terminal elimination half-lives were 14.7, 9.1 and 22.7 min following IV, IP and PO dosing, while the absolute bioavailability for IP and PO WA were 9.39% and 0.58% respectively.These results indicated that the HPLC-APCI-MS/MS assay was suitable for the pharmacokinetic study of WA. WA was found poorly absorbed when given orally and therefore it may not be a relevant marker for the oral TW products in the market.

N-nitrosamines migrating from food contact materials into food simulants: analysis and quantification by means of HPLC-APCI-MS/MS

ABSTRACTIt was the aim of the work described here to develop a validated analytical method for the determination of N-nitrosamines in food simulants. Here, we present the validation of a liquid chromatography–atmospheric pressure chemical ionisation–tandem mass spectrometry method for the determination of 13 N-nitrosamines in the food simulants deionised water, 3% acetic acid and 10% ethanol. Method validation encompassed linearity, LOD, LOQ, recovery, precision and stability of the N-nitrosamines. The method was found to be sufficiently rugged and suitable for routine analysis. In addition, the developed method is on average 10 times more sensitive than the gas chromatography–thermal energy analyser (GC-TEA) method that is currently stipulated in Recommendation XXI for commodities based on natural and synthetic rubber issued by the German Federal Institute for Risk Assessment (BfR). The developed method was applied to determine the N-nitrosamine contents in migration solutions of 12 elastomer samples covering a range of different elastomer types. In 10 out of 12 samples, N-nitrosamines were determined. In most samples, the guidance value of 1 µg/dm2 specified in BfR Recommendation XXI was not exceeded. In conclusion, the analytical method presented here offers a useful alternative to the GC-TEA method currently stipulated in BfR Recommendation XXI. This is of wider relevance, since BfR recommendations are used for compliance assessment of Article 3, paragraph 1 a of the Regulation (EC) No. 1935/2004 with respect to their health safety.

UHPLC-APCI-MS Profiling of Triacylglycerols in Vegetable Oils—Application to the Analysis of Four North African Sesame Seed Varieties

Here, we describe an isocratic ultra-high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (UHPLC-APCI-MS) method for the characterization and the quantification of triacylglycerols (TAGs) in vegetable oils. The linearity and the precision of the method are validated, and the limits of detection are estimated. The APCI-MS detector shows a linear response from 1 to 1000 μg/mL, and the correlation coefficients (r2) obtained for standards TAGs exceed 0.995. As compared to previous methods, the proposed method is rapid, simpler, and more sensitive. The limits of detection estimated for several standard TAGs varies from 0.03 to 0.05 injected nanograms (6 to 10 μg/L). The application of the proposed method to the analysis of sesame oil allowed us to unambiguously identify 30 TAG species whereas previous methods have detected 19 TAGs, at the most. Among vegetable oils, sesame oil became an attractive target for adulteration due to its high commercial value. Most of the previous studies of TAG profiles of sesame oils had been devoted to the analysis of sesame oils originating from Asia and some Sub-Saharan countries. To the best of our knowledge, the TAG profiles of sesame oils from other origins are still unknown. The results we obtained for the four Tunisian sesame seed varieties clearly indicate that sesame oils can be classified according to their equivalent carbon number differences (ΔECN) with some rules similar to those required for olive oils.

Comprehensive chemical profiling of Pinellia species tuber and processed Pinellia tuber by gas chromatography–mass spectrometry and liquid chromatography–atmospheric pressure chemical ionization–tandem mass spectrometry

A comprehensive profiling method was established for the determination of various chemicals in Pinellia (P.) ternata and pedatisecta species. The profiling method comprises a fast ultrasonic extraction with various solvents, followed by GC–MS and LC–APCI-MS analysis. A total of 73 polar components as trimethylsilyl (TMS) derivatives were detected in methanol extract by GC–MS. The main components of the P. species were profiled as several kinds of fatty acids, amino acids, nucleic acids, carbohydrates, and phenolic compounds. The hexane extract was analyzed by LC–APCI-MS for the lipid profiling. A total of 35 lipid constituents [fatty acids and their esters, mono-, di-, and tri-acylglycerols] and four phytosterols were observed and tentatively characterized by LC–APCI-MS/MS. Among the phytochemicals detected in the hexane extract, triacylglycerols (TAGs) as the major component were identified by LC–APCI-MS and MS/MS. Based on the identified components, a significant difference in the chemical compositions of P. species tuber and processed P. ternata was found that the complete disappearance of TAGs and a considerable decrement of sucrose were observed in processed P. ternata. Furthermore, the degradation mechanism for TAGs in the presence of alum solution is suggested to occur during the processing P. ternata. Malic acid was found to be a characteristic compound for the classification of P. ternata and pedatisecta with different geographic origins. Based on the validated GC/MS method, twenty-four P. ternata, processed P. ternata and P. pedatisecta samples were profiled to measure the overall abundance of specific groups of compound and to identify diagnostic compounds. In addition, principal component analysis (PCA) on the GC/MS profiling data revealed a clear classification of P. species samples. In this study, the full chemical complement was for the first time reported for quality evaluation of P. species. The method can be usefully applied for phytochemical analysis of related herbal medicines.