Solid phase extraction with high polarity Carb/PSA as composite fillers prior to UPLC-MS/MS to determine six bisphenols and alkylphenols in trace level hotpot seasoning

Modified QuEChERS purification and Fe3O4 nanoparticle decoloration for robust analysis of 14 heterocyclic aromatic amines and acrylamide in coffee products using UHPLC-MS/MS

Based on QuEChERS dispersed purification, Fe₃O₄ nanoparticle decoloration and UHPLC-MS/MS, a robust and sensitive method was established for simultaneous analysis of 14 heterocyclic aromatic amines (HAAs) and acrylamide (AA) in coffee products. Sample was extracted by 90% acetonitrile water (v/v), dispersed with primary secondary amine (PSA) and further purified with Fe₃O₄ nanoparticle. Then, 15 analytes were detected using ESI positive ion under MRM mode. Good linearity was observed for all analytes in the range of 0.2-100 μg/L with the determination coefficients being above 0.996. Limits of detection (S/N ≥ 3) and limits of quantification (S/N ≥ 10) were in the range of 0.02-0.15 µg/L and 0.2-0.7 µg/L, respectively. The intra-day average recoveries were between 81.6% and 100%, and the intra-day precisions ranged from 4.3% to 9.0%. The inter-day average recoveries were in the range of 81.0-101% with precisions ranging from 5.0% to 7.8%. Results indicated that the combination of PSA and Fe₃O₄ exhibited superior purification and adsorption effects for removing pigments and acid compounds. Real samples analysis indicated that coffee products were widely contaminated with AA, harman and norharman.

Simultaneous detection of multiple hydroxylated polychlorinated biphenyls from biological samples using ultra-high-performance liquid chromatography with isotope dilution tandem mass spectrometry

We established a method for the separation and detection of nine hydroxylated polychlorinated biphenyls in whole blood and urine samples using ultra high performance liquid chromatography coupled with electrospray negative ionization tandem mass spectrometry. Clean-up procedures involved a filtration step, and optimization involved a pretreatment step consisting of a simple liquid-liquid extraction using hydrated silica-gel chromatography (5%). Nine hydroxylated polychlorinated biphenyls were separated on an ultra high performance liquid chromatography HSS T3 column using a gradient elution program of 2 mmol ammonium formate aqueous solution (A) and methanol (B). Recovery ranged from 84.0 to 105.4% for the nine different hydroxylated polychlorinated biphenyls in urine with three spiked levels of 0.1, 1, and 2 ng and from 73.5 to 98.6% for the blood with spiked levels of 0.2, 1, and 2 ng. The relative standard deviations were <8.7% (n = 6), and the limits of detection in urine and whole blood for the nine hydroxylated polychlorinated biphenyls were in the range of 1.5-4 and 20-100 pg/g, respectively. This analytical method may enable the simultaneous detection of various hydroxylated polychlorinated biphenyls from complex tissue matrices.

Simultaneous analysis of 2-methylimidazole, 4-methylimidazole, and 5-hydroxymethylfurfural potentially formed in fermented soy sauce by "quick, easy, cheap, effective, rugged, and safe" purification and UHPLC with tandem mass spectrometry

2-Methylimidazole, 4-methylimidazole and 5-hydroxymethylfurfural are harmful by-products potentially formed via Maillard reaction in fermented soy sauce. The present study proposed a new method based on "quick, easy, cheap, effective, rugged, and safe" purification and ultra high performance liquid chromatography with tandem mass spectrometry for the simultaneous analysis of 2-methylimidazole, 4-methylimidazole and 5-hydroxymethylfurfural in fermented soy sauce. The sample was dissolved in water after addition of internal standard 4-methylimidazole-d₆ and extracted with acetonitrile. After dehydration, it was centrifuged and the supernatant was subsequently purified using two sorbents namely primary-secondary amine and multi-walled carbon nanotube. Three target analytes were separated by gradient elution and determined under multiple reactions monitoring mode. The limit of detection, matrix effect, recovery and precision of the developed method were investigated. Results found that three target analytes displayed excellent linearity in concentration range of 1-250 μg/L. Limit of detection was in the range of 0.3-1 μg/kg for three target analytes. The mean recoveries for fermented soy sauce samples at three spiked concentrations were in the range of 91.2-112.5%, and the intra- and interday precision were in the ranges of 3.6-9.2 and 7.1-10.8%, respectively. This validated method was successfully applied to determine 2-methylimidazole, 4-methylimidazole and 5-hydroxymethylfurfural concentrations in fermented soy sauce.

Analysis of the dissipation kinetics of thiophanate-methyl and its metabolite carbendazim in apple leaves using a modified QuEChERS-UPLC-MS/MS method

As one of the main fungicides for the apple leaf disease control, thiophanate-methyl (TM) mainly exerts its fungicidal activity in the form of its metabolite carbendazim (MBC), whose dissipation kinetics is very distinct from that of its parent but has been paid little attention. The aim of this work was to investigate the dissipation kinetics of TM and its active metabolite MBC in apple leaves using a modified QuEChERS-UPLC-MS/MS method. The results showed that TM and MBC could be quickly extracted by this modified QuEChERS procedure with recoveries of 81.7-96.5%. The method linearity was in the range of 0.01-50.0 mg kg^-1 with the quantification limit of 0.01 mg kg^-1 . Then this method was applied to the analysis of fungicide dissipation kinetics in apple leaves. The results showed that the dissipation kinetics of TM for the test in 3 months can be described by a first-order kinetics model with a DT₅₀ (dissipation half-life) range of 5.23-6.03 days and the kinetics for MBC can be described by a first-order absorption-dissipation model with the T_max (time needed to reach peak concentration) range of 4.78-7.09 days. These models can scientifically describe the behavior of TM and MBC in apple leaves, which provides necessary data for scientific application.

Development and comparison of single-step solid phase extraction and QuEChERS clean-up for the analysis of 7 mycotoxins in fruits and vegetables during storage by UHPLC-MS/MS

A robust and sensitive UHPLC-MS/MS method was developed for the analysis of seven mycotoxins in fruits and vegetables. The variations of seven mycotoxins concentrations during storage were also determined for the first time. Solid phase extraction (SPE) and QuEChERS clean-up were compared, and extraction was finally performed with acetonitrile under acidic conditions followed by HLB SPE purification. Seven mycotoxins were separated on a C18 column by gradient elution, scanned by ESI⁺ and ESI^- dynamic switching and detected with MRM mode. LOD and LOQ, matrix effect, accuracy and precision of the developed method were investigated. Results were linear in their concentration ranges for all mycotoxins with R² being greater than 0.999. LODs and LOQs were ranged from 0.05 to 3.0 μg/kg and 0.2 to 10.0 μg/kg, respectively. Average recoveries were between 81.1% and 116% with intraday- and interday-precision being in the ranges of 3.0-6.2% and 4.2-6.1%, respectively. The validated method provides sufficient selectivity, sensitivity and accuracy to screen for seven mycotoxins at trace levels, without using standard addition or matrix-matched calibration to compensate for matrix effects. The method was successfully applied for mycotoxins analysis in fruits and vegetables. None were detected in fresh samples, but AOH and AME were detected in strawberry, and TeA was detected in tomato fruits during long-term storage. Their concentrations were in the range of 3.6-165.3 μg/kg from 3 days to 60 days and significantly increased along with storage time.

Rapid determination of hexavalent chromium in textiles by a novel ammonium pyrrolidine dithiocarbamate derivatization combined with UHPLC-MS/MS

Hexavalent chromium is mainly determined by traditional spectrophotometry, atomic absorption spectrometry, and ion chromatography methods. In the present work, a reliable ultra high performance liquid chromatography with tandem mass spectrometry method was firstly developed for the determination of hexavalent chromium in textiles. The sample was extracted by acetic acid/sodium acetate buffer solution and followed by derivatization with ammonium pyrrolidine dithiocarbamate. The resulting derivative product was extracted by ethyl acetate, separated on a C18 column, and detected through electrospray ionization source in the positive mode with multiple reaction monitoring conditions. The derivatization reaction conditions were investigated and optimized. The developed method was validated in terms of the sensitivity, linearity range, matrix effects, recovery, accuracy, intra- and interday precision. Results showed that the calibration curves of pure solvent and matrix were linear over the selected concentration ranges of 0.1-20.0 μg/L. The achieved instrument and method limit of quantification were 0.1 and 40.0 μg/kg, respectively. Recoveries were calculated at three spiked concentrations and the values were between 92.2 and 103% with relative standard deviation values of 2.7-4.9% for intra-day precision and 6.1% for inter-day precision. Successful analysis of hexavalent chromium in practical textiles indicated that there was hexavalent chromium contamination in textiles.

Quantitative determination of doxorubicin in the exosomes of A549/MCF-7 cancer cells and human plasma using ultra performance liquid chromatography-tandem mass spectrometry

In cancer therapy, exosomes efflux enhances resistance of cancer cells toward anticancer agents through mediating the transport of anticancer drugs outside the cells. In this study, a rapid, simple and highly sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of Doxorubicin (DOX) in exosomes of cancer cells and human plasma using Ketotifen as an internal standard (IS). Plasma samples spiked with DOX and two cancer cell lines (A549 & MCF-7) were incubated with different concentrations of DOX and IS. The analytes were then extracted with methanol after protein precipitation and the chromatographic separation was carried out using a C18 column, with a mixture of acetonitrile–water- formic acid (85:15:0.1%, v/v/v) as mobile phase. Multiple reaction monitoring (MRM) was utilized to monitor the protonated precursor to product ion transitions of m/z 544.25 > 397.16 and m/z 310.08 > 96.97 for the quantification of DOX and IS, respectively. The method was linear over ranges of 1–1000 ng/mL for DOX in plasma and 2–1000 ng/mL for DOX in exosome samples. The lower limit of quantification of this method was 1 ng/mL, 2 ng/mL and 2 ng/mL in human plasma, A549 & MCF-7 cells respectively. Intra- and inter day precision of all quality control concentrations were less than 10.33% and the accuracy values ranged from −4.82 to 12.60%. The optimized UPLC-MS/MS method proved to be fast, specific, simple and highly sensitive and was successfully applied for the estimation of DOX in the exosomes of cancer cells and plasma.