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Objective: To establish a method for the determination of three furfural compounds in coffee and its products by gas chromatography-tandem mass spectrometry., Methods: The samples were extracted with ethanol water(1∶2, V∶V) solution, ultrasonic with 10% Na_2CO_3 solution for 5 min, purified with 100 mg C_(18), 50 mg Srong Cation exchang(SCX), 150 mg anhydrous MgSO_4, separated by HP-INNOWAX capillary column(30 m×0.25 mm, 0.25 μm), detected by gas chromatography-tandem mass spectrometry, and quantified by isotope internal standard method., Results: The correlation coefficients(r) of the three furfural compounds were all greater than 0.999, the limits of detection were 0.004-0.011 mg/kg, and the limits of quantitation were 0.013-0.031 mg/kg. The average recoveries were 86.0%-112% and the relative standard deviations were 4.1%-10.6%(n=6), at 3 supplemental levels in 3 different coffee substrates. Nine samples of coffee beans, instant coffee and coffee drinks were tested, and all three components to be tested were detected., Conclusion: The method is simple, rapid, sensitive, with good accuracy and precision. It is suitable for the determination of three furfural compounds in coffee and its products.

Objective: To establish a rapid, accurate and sensitive method by liquid chromatography-tandem mass spectrometry with isotope internal standard dilution technique for the determination of chlorpromazine and promethazine and their metabolites in swine tissues., Methods: The swine tissues sample was extracted with acetonitrile and purified on MCX cartridge. The liquid chromatography separation was performed on an ACQUITY UFLC® HSS T3(100 mm×2.1 mm, 1.8 μm) with a linear gradient elution program of 0.1%(V/V) fomic acid-acetonitrile and 0.1%(V/V) formic acid-water solution as the mobile phase. The analytes were analyzed using ESI operating in the positive multiple reaction monitoring(MRM) mode., Results: The limits of quantitation(LOQs) and limits of detection(LODs) for the target objects were 0.12-0.51 μg/kg and 0.04-0.17 μg/kg, respectively. The calibration curves were linear in range of 0.1-20.0 μg/L for chlorpromazine and promethazine, and 0.5-100.0 μg/L for their metabolites(chlorpromazine sulfoxide and isopropyl sulfoxide). The recoveries were between 90.8%-106.0%, and the relative standard deviations(RSDs) were between 1.9%-6.2%(n=6)., Conclusion: The method is highly sensitive and accurate, and is suitable for the analysis of chlorpromazine and promethazine and their metabolites(chlorpromazine sulfoxide and isopropyl sulfoxide) in swine tissues.

As among the most widely used pesticides in agriculture, plant growth regulators (PGRs) have a positive influence on plants. However, the overuse of PGRs may induce toxicity in food and even be hazardous to human health. Numerous studies have investigated the presence and residues of PGRs on vegetables and fruits. Animal-derived foods are one of the most dominant food sources providing nutrients to fulfil the daily dietary intake, and could also be potentially contaminated by PGRs. However, there is little information on PGR residues in animal-derived foods. Standardization also lacks among the techniques for PGR determination in animal-derived foods, thereby restricting the further establishment of pesticide usage and food safety regulations. Therefore, in this study, a rapid and effective method for analyzing chlormequat chloride, thidiazuron, and paclobutrazol in animal-derived food samples was established. The method primarily involves high performance liquid chromatography-tandem mass spectrometry combined with the use of isotope-labeled internal standards. The extraction and clean-up procedures were based on the QuEChERS method. The analytes were extracted from pork, beef, chicken, pork liver, egg, and milk samples using acetonitrile, followed by 4 g anhydrous magnesium sulfate (MgSO 4 ), and 1 g sodium chloride (NaCl). The supernatant was removed using a mixture of 50 mg N -propyl ethylenediamine (PSA), 50 mg octadecyl silane (C18), and 150 mg MgSO 4 , and then passed through a 0.22 μm membrane filter before determination. The Agilent ZORBAX Eclipse Plus C18 column (150 mm×3.0 mm, 1.8 μm) was used to separate the analytes under a gradient elution program, with acetonitrile and 5 mmol/L ammonium acetate solution as mobile phases. The analytes were detected by mass spectrometry using the positive and negative electrospray ionization modes under the multiple reaction monitoring mode. Matrix-matched calibration combined with internal standards was used to quantify the PGRs. The linear regression correlation coefficients ( r 2 ) for the PGRs were all greater than 0.990 in the corresponding linear concentration ranges. Chlormequat chloride, thidiazuron, and paclobutrazol showed good linearities in the range of 0.1-100 μg/L for the egg and pork liver samples and 0.1-50 μg/L for the pork, beef, and chicken samples. For the milk samples, thidiazuron and paclobutrazol showed good linearities in the range of 0.05-10 μg/L, while chlormequat chloride showed linearity in the range of 0.05-5 μg/L. The limit of detection (LOD) and limit of quantification (LOQ) for each PGR were based on the signal-to-noise ( S/N ) ratios. Under optimal conditions, the LODs ranged from 0.01 μg/kg to 0.1 μg/kg, where the LOD was defined as the amount of the tested compound that generated an S/N ratio higher than 3. In addition, the LOQs were in the range of 0.5-5 μg/kg, with an S/N ratio higher than 10. The precision and accuracy were evaluated by recovery experiments. At the LOQ, twice the LOQ, and 10 times the LOQ, the mean recoveries were in the range of 70.0%-117.4%, and the relative standard deviations (RSDs) ranged from 0.8% to 16.1%. The results indicated that the proposed method is accurate and reliable. This method is a modification of the QuEChERS method, and is advantageous owing to its simplicity and high sensitivity. The use of matrix-matching calibration curves and internal standards can eliminate matrix interference, thereby increasing the accuracy of the method. This method satisfies the testing requirements for chlormequat chloride, thidiazuron, and paclobutrazol residues in animal-derived foods, and is promising for the determination of other PGRs or other types of pesticides in animal-derived foods.

Objective: To establish a rapid and accurate method for determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3 in serum by isotope dilution ultra-fast liquid chromatography-tandem mass spectrometry(UFLC-MS/MS)., Methods: The serum sample was extracted by nhexane after methanol/acetonitrile precipitation protein, and then the extract was concentrated by nitrogen and volumed with the primary mobile phase. The chromatographic separation was carried out on a Phenomenex Kinetex F5 column(2. 1 mm × 150 mm, 1. 7 μm) by using 0. 1%(V/V) formic acid and 0. 1%(V/V) formic acid/methanol solution as the mobile phase with the gradient elution. Detection was performed in positive multi-reaction monitoring(MRM) mode with the isotope internal labeling method for quantification., Results: The baseline separation was obtained within 6 min for the epimer 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3, and the accurate qualification was obtained for the simultaneous determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3. The three analytes showed good linear relationship within the range of 0. 5-50. 0 μg/L with a correlation coefficient r >0. 9995. The limits of detection(LODs) and the limits of quantitation(LOQs) of the method were 0. 15 μg/L and 0. 5 μg/L, respectively. The recoveries of the method were84. 3%-109. 0%(n = 11) at the three spiked levels of 1. 0, 10. 0 and 30. 0 μg/L, and the relative standard deviations(RSDs) were between 0. 8%-6. 8%. At the same time, the certified standard reference materials(SRM) of the America National Institute of Standards and Technology(NIST) Level 1, Level 2, Level 3 and Level 4(SRM 972 a)were used as the quality control samples for verification, the relative deviations of the measurement result were less than 5% compared with the reference values., Conclusion: The developed method has the characteristics of simplicity, rapidity, sensitivity and accuracy, and is suitable for the simultaneous rapid determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3 in serum.

A method was developed for the determination of monofluoroacetic acid (MFA) in plasma and urine by ion chromatography-triple quadrupole mass spectrometry (IC-MS/MS). A plasma sample was extracted with 3% (v/v) perchloric acid aqueous solution, and the extract was centrifuged to remove the protein and lipids. A urine sample was acidulated with 3% (v/v) perchloric acid aqueous solution. The target analyte was extracted with methyl tert -butyl ether (MTBE) at a pH between 0.5 and 1.0. After the MTBE was removed by blowing with nitrogen, the MFA in the residues was dissolved into 0.1% (v/v) ammonia solution. The separation of MFA was carried out on a Dionex Ionpac AS 19 analytical column (250 mm×2 mm, 7.5 μm) with gradient elution using KOH solution electrolytically generated from an on-line eluent generation cartridge. Before the eluent flow entered the mass spectrometer, an in-line suppressor was used to remove potassium ions. The MFA was detected with a negative electrospray ionization source in the multiple reaction monitoring (MRM) mode, and quantified with the stable isotope internal standard method. The correlation coefficient of the linear calibration curve of MFA was greater than 0.999 at the corresponding ranges of 0.1-1000 μg/L. The average recoveries were 96.2%-120% of MFA in plasma and urine samples with relative standard deviations of 1.1%-13.1% ( n =6). The limits of detection of MFA in plasma and urine samples were 0.03 μg/L and 0.1 μg/L, respectively. The method is simple, sensitive and accurate, and can be applied for the determination of MFA in plasma and urine samples.

Objective: To develop a method for determination of creatinine in human urine by isotope dilution high performance liquid chromatography/tandem mass spectrometry., Methods: The urine samples were directly diluted 800 fold by mixed solution of methanol and water( 7 ∶ 3, V/V), and filtered with 0. 45 μm filter. The chromatographic separation was carried on an Atlantis Hilic Silica column( 2. 1 mm × 150 mm, 3 μm). Methanol and water mixture solution( 7 ∶ 3, V/V) were used as the mobile phases in an isocratic gradient. Mass detection was then conducted by electrospray ionization in positive ion( ESI+) mode and multiple reaction monitoring( MRM) mode. The concentration of creatinine was quantified by stable isotope labelled d3-creatinine internal standard. Standard reference material of urine creatinine was used to evaluate the accuracy of method, and then the uncertainty of this detection method was also evaluated., Results: The calibration curve of creatinine showed a good linear relationship in the range of 0. 31 μg/mL to 5. 00 μg/mL, and the related coefficient was 0. 999 9. The limit of detection( LOD) and limit of quantitation( LOQ) were 0. 003 mg/mL and 0. 011 mg/mL respectively, in real urine. Recoveries rates at two levels were 93. 9%-104. 0% and 90. 6%-93. 8%, with the relative standard deviation of 4. 4%-7. 6% and 4. 6%-7. 8%( n = 6), respectively. The creatinine concentration of standard reference material was in accordance with the reference value. The measurement uncertainty was mainly due to standard curves, recoveries rates and permissible error of instrument., Conclusion: The determination method is successfully applied to measure the concentration of creatinine in human urine with efficiency, accuracy and high sensitivity.

A rapid method was established for the determination of zearalenone (ZON), nivalenol (NIV), deoxynivalenol (DON), 3-acetyl-deoxynivalenol (3-ACDON) and 15-acetyl-deoxynivalenol (15-ACDON) in various grains and their products by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted by acetonitrile-water (84:16, v/v), and cleaned-up by multifunctional column without any further step. The separation was carried out on an Acquity UPLC ® BEH C18 column (100 mm×2.1 mm, 1.7 μm) with gradient elution using acetonitrile-water as mobile phases. The analytes were quantified by isotope internal standard method. The correlation coefficients ( r 2 ) were all above 0.99. The limits of detection (LODs, S/N =3) ranged from 5 μg/kg to 20 μg/kg. The recoveries of the five mycotoxins spiked in blank grain and its product samples varied from 84.2% to 114.5%, with the relative standard deviations (RSDs) of 0.4%-9.9% ( n =6). The method is accurate, efficient, sensitive and practical.

An accurate method was described for the determination of chloramphenicol (CAP) in pork. The analyte was quantified by isotope dilution liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) operating in negative ion multiple reaction monitoring (MRM) mode. The sample was treated by liquid-liquid extraction with ethyl acetate followed by a clean-up step on an HLB solid-phase extraction cartridge. Chloramphenicol-D5 (CAP-D5) was added as an isotope internal standard. Under the optimized conditions, the calibration curve showed a good linearity in ranging from 0.01 to 0.5 ng/g CAP. The correlation coefficient r2 was 0.9998. The limit of detection and the limit of quantification were 0.004 and 0.02 ng/g, respectively. The average recoveries of CAP at 0.02 ng/g and 1.0 ng/g spiked levels ranged from 95.2%-109.1%, 99.7%-102.5%, respectively. The relative standard deviations (RSDs) of intra-day and inter-day were less than 2%. Meanwhile, matrix effect factors k of CAP and CAP-D5 were determined under different mobile phases and the sample solvent composition, the k was in the range of 0.950-1.015. The method can be used as a confirmed method for the determination of CAP in pork.

Objective: A sensitive method based on isotope dilution gas chromatography tandem mass spectrometry is described for the determination of the antibiotic chloramphenicol (Cap) in shrimp tissue., Methods: Homogenized shrimp samples spiked with an isotopically labeled internal standard (d5-Cap) were extracted with ethyl acetate extraction, defatted with hexane, followed by a clean-up step on a SPE C18 cartridge, and then the elute was evaporated and derivatized with Sylon BFT {N,O-bis (trimethylsily) trifluoroacetamide[BSTFA]-trimethylchlorosilane [TMCS] ,99 + 1}. Analyzes were determined by GC/MS-MS in MRM mode., Results: Internal calibration curves obtained for Cap/ d5-Cap in the 5 to 500 pg range were linear with correlation coefficients of 0.9958. Limit of quantitation (LOQ) was 0.3ng/g. Shrimp tissues were fortified with Cap at 0.3, 0.5, 1.0 ng/g level, average recoveries were 104%, 111% and 95% , respectively., Conclusion: The proposed method allows the detection, quantitation and confirmation of Cap in shrimps with high accuracy and sensitivity.

"Tobacco-free" or synthetic nicotine products have been favored by the majority of young people, which undoubtedly increase the potential health risks and regulatory challenges. Currently, there are few reliable methods for the determination of authenticity of natural nicotine and synthetic nicotine. The analytical techniques based on mass spectrometry have broad application prospects in component sequence analysis. structure analysis, molecular weight determination and component content determination. The synthesis processes of natural nicotine and synthetic nicotine are different, and their isotopic fractionations are also different. Here, a method of tandem mass spectrometry based on isotope model peak was developed using this feature. The source or naturalness of nicotine is verified by comparing the abundance and area ratio of [M + H]+ and [M+H+1]+ peaks of nicotine, and the abundance ratio of [M+H]+ and [M+H+1]+ peaks as fragments of parent ions. A total of 47 experimental results showed that the m/z 164. 1. 163. 1 peak abundance ratios and the area ratios of natural nicotine and synthetic nicotine in MS spectra were significantly different. In addition, in MS/MS spectra, the abundance ratios of fragment ions of m/z 163. 1. 164. 1 also had significant differences. Among the variables with significant differences. the overall abundance ratio of synthetic nicotine was higher than that of natural nicotine. The evaluation model for the identification of natural nicotine and synthetic nicotine was further constructed by combining chemometric methods. Using OPLS-DA modeling, the discriminant accuracy was 97. 87%. Moreover, rankings of importance of variables differed depending on the model of the evaluation. 164. 1-85. 1/84. 1, 164. 1-85. 1/(84. 1+85. 1), 163. 1-131. 1/131. 1. 163. 1-131. 1/(130.1+131. 1) were the key discriminant variables. This method has the advantages of simple operation, rapid operation and no need for quantitative analysis, which will help to accurately identify, label and supervise tobacco products from different nicotine sources on the market. [ABSTRACT FROM AUTHOR]