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@#Objective - To optimize the extraction and quantification methods for the determination of S phenylmercapturic acid - Methods (SPMA) in urine with performance liquid chromatography mass spectrometry. The urine was hydrolyzed with 50.0% sulfuric acid. The hydrolysate was purified by solid phase extraction column. Purified samples were separated by C18 chromatographic column and detected by tandem mass spectrometry. The isotope labeled SPMA was used as the internal Results - standard. The internal standard curve was used for quantification. The linear range of SPMA was 0.50 50.00 μg/L with the correlation coefficient of 0.999 8. The detection limit and the lower limit of quantification were 0.05 and 0.17 μg/L, - - - - respectively. The recovery rate was 97.0% 102.0%. The within run and between run relative standard deviation were 0.6% 1.0% - and 1.7% 6.5%, respectively. The mass concentration of urinary SPMA in the occupational benzene exposure group was - vs P higher than the non occupational benzene exposure group by this method (median: 2.81 0.28 μg/g creatinine, <0.05). Conclusion Compared to the national standard method, this optimized method of solid phase extraction and internal standard for quantification eliminates the matrix effect. This method is accurate and precise, and is suitable for the determination of SPMA acid in urine.
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Cordycepin,which has great immunomodulatory activities such as anticancer,antifungal,antivirus,antileukemia and lipid-lowering ones,is the secondary metabolite of Cordyceps militaris (C.militaris).Liquid submerged fermentation is the common cultivation process to produce cordycepin.To optimize the fermentation process and improve production,monitoring the cordycepin secretion in the fermen-tation is essential.The measurement based on chromatography-mass spectrometry methods is generally involved in the complex sample pretreatments and time-consuming separation,so more rapid and convenient methods are required.Matrix-assisted laser desorption ionization mass spectrometry(MALDI-MS) is more attractive for faster and direct detection.Therefore,MALDI-MS detection combined with isotope-labeled internal standard was applied to the measurement of cordycepin content in the fermentation broth and mycelium.This method made accurate quantification of cordycepin in the range of 5-400 μg/mL with a relative standard deviation of 5.6％.The recovery rates of fermentation samples after the 1,13,and 25 days were 90.15％,94.27％,and 95.06％,respectively.The contents of cordycepin in the mycelium and fermentation broth were 136 mg/g and 148.39 mg/mL on the 20th culture day,respectively.The cordycepin secretion curve of the liquid fermentation of C.militaris was real-time traced over 25 days.
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OBJECTIVE： To establish a method for determination of fluconazole concentration in human plasma. METHODS： UPLC-MS/MS method was adopted to determine plasma after precipitated with acetonitrile. Using isotope fluconazole-d4 as internal standard， the determination was performed on ACQUITY UPLC BEH C18 column with mobile phase consisted of 0.1％ formic acid-acetonitrile （gradient elution） at the flow rate of 0.3 mL/min. The column temperature was 40 ℃， and the sample size was 3 μL. ESI was used for positive ion scanning by multiple reaction monitoring mode. The ion pairs for quantitative analysis were m/z 307.1→220.0 （fluconazole） and m/z 311.1→223.0 （internal standard）. RESULTS： The linear range of fluconazole was 10-5 000 ng/mL （r＝0.998 1）. The limits of quantitation was 10 ng/mL. RSDs of intra-day and inter-day were less than 8％； accuracy ranged 95.8％-106.7％. The extraction recovery ranged 97.3％-107.3％ （RSD＜5.0％， n＝6）， and matrix effect， dilution effect and residual effect didn’t influence quantitative analysis of the substance to be measured. CONCLUSIONS： The method is simple， rapid， specific and accurate， which can be used for therapeutic drug monitoring and pharmacokinetic study of fluconazole.
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A suitable ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of 11 mycotoxins with isotope internal standard in malt. The mycotoxins in malt were extracted and purified by one-step ultrasonic extraction procedure using acetonitrile/water/acetic acid (80:19:1), and then detected and confirmed by UPLC-MS/MS, and quantified by isotope labeled AFB1 ([13C17]-AFB1) and ZEN ([13C18]-ZEN) internal standards. Rapid separation of the 11 mycotoxins was successfully achieved on a Phenomenex Kinetex C18 column (100 mm × 2.1 mm, 2.6 μm) with gradient elution using the mobile phase of methanol containing 0.1% formic acid and 2 mmol·L-1 ammonium acetate in water. Simultaneous acquisition was performed in multiple reaction monitoring (MRM) mode with electrospray ionization (ESI) source operated in both positive and negative ionization modes. The established method provided a good linearity for the 11 mycotoxins within their respective linear ranges with correlation coefficients all higher than 0.999 1. The average recoveries ranged from 75.0% to 117.0% with relative standard deviations (RSDs) below 5.1%. The limits of detection (LODs) and quantitation (LOQs) ranged from 0.05 to 30 μg·kg-1 and 0.15 to 87.5 μg·kg-1, respectively, which were below the maximum residue levels (MRLs) set by the European Union. Twenty malt samples were analyzed and nine samples were detected with mycotoxins, which were confirmed according to the same fragment ions found in positive samples and the standards at the same retention time. This study has demonstrated that the one-step extraction procedure of mycotoxins from complex matrices coupled to UPLC-MS/MS method is simple, quick, accurate and sensitive for quantitative and qualitative analysis of multiple mycotoxins in malt.
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OBJECTIVE: To develop a GC-MS/MS method for the determination of the residues of 16 polycyclic aromatic hydrocarbons (PAHs) in Chinese herbal medicines. METHODS: Using isotope as internal standard, the sample was extracted by ethyl acetate and purified by solid phase extraction on C18 cartridges. GC-MS/MS method was used for the assay, with analyte protectants added to counteract the matrix effect. The chromatographic column was DB-5ms(0.25 mm × 30 m, 0.25 μm) with temperature programming and MRM detection. RESULTS: The calibration curves for the 16 kinds of typical PAHs were linear in the range of 1 - 100 ng · mL-1. The average recovery rate was 88.53% - 119.03% in the range of 1 -25 μg · kg-1 with RSDs of 1.25% - 14.70% (n = 3). The LOQs were 0.2 - 1 μg · kg-1. CONCLUSION: This method is specific, sensitive, accurate and can be used for residue detection of 16 typical kinds of PAHs in Chinese herbal medicines.