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Objective@#To develop an approach for simultaneous detection of multi-mycotoxins in fresh fruits, so as to provide technical supports for mycotoxins surveillance in fresh fruits.@*Methods@#Fresh fruits were collected from markets and homogenized. Then, 2 g of fresh fruits were added with 10 mL of 0.1% formic acid ( 99∶1, v/v ) in acetonitrile and wortexed for 10 min. Following extraction with 1 g of sodium chloride and 4 g of anhydrous sodium sulfate, samples were centrifuged and 5 mL of the supernatant was cleaned up with 25 mg C18. Following centrifugation, the supernatant was dried under nitrogen. The residue was dissolved in 300 μL of methanol-acetonitrile mixture solution ( 1∶1, v/v ), and mixed evenly in 700 μL of the distilled water. Samples were then eluted in gradient series of 0.1% formic acid and 5 mmol ammonium formate and methanol-acetonitrile mixture solution ( 1∶1, v/v ). The 15 mycotoxins were determined using liquid chromatography-tandem mass spectrometry ( LC-MS/MS ) with electrospray ion source (ESI+/ESI-) under multiple reaction monitoring. In addition, a matrix-matched standard curve was employed for quantitative analysis.@*Results@#There was a good linear relationship for 15 mycotoxins at concentrations of 0.25 to 10 ng/mL ( R2>0.992 ), the LC-MS/MS method showed the detection limits of 0.1-1.0 μg/kg, the spiked recovery rates of 71.68%-117.50%, and the relative standard deviations ( RSDs ) of 0.01%-13.60%. The detection rate of mycotoxins was 27.09% in 203 fresh fruits sold in markets.@*Conclusions@#The optimized LC-MS/MS method can be used for simultaneous determination of multi-mycotoxins in fresh fruits.
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Objective@#To quickly determine bongkrekic acid（BKA）in plasma qualitatively and quantitatively by liquid chromatography-tandem mass spectrometry（LC-MS/MS）,and to provide technical support for etiological identification of food poisoning events.@*Methods@#The plasma sample was protein precipitated with acetonitrile,diluted with water and purified with anion exchange solid phase extraction cartridge of PAX. The sample extract was separated by an XBridgeTM BEH C18 chromatographic column. Gradient elution was conducted with the mobile phase of 0.01 %（v/v）ammonia and methanol. Then BKA was detected by LC-MS/MS. @*Results@#The equation of linear regression was y=16 509x+3 134.3. Good linear relationship was obtained for BKA at a range from 1 to 400 ng/mL in plasma,with the correlation coefficient of 0.999 3. The limit of detection（LOD）was 0.5 ng/mL and the limit of quantitation（LOQ）was 1 ng/mL. The average recoveries were 76.0%-96.7% with relative standard deviations（RSDs,n=6）of 5.2%-12.8% at three spiking levels of 1（LOQ）,10（10 times of LOQ）and 200 ng/mL（medium of linear range）. The concentrations of BKA in plasma obtained from two patients suffering from food poisoning were 394 and 92.3 ng/mL. @*Conclusion@#The optimized sample pretreatment and chromatographic separation conditions can achieve rapid,accurate,qualitative and quantitative analysis of BKA in plasma.
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Objective@#To screen and quantify 16 kinds of β-lactam antibiotics in pork by high performance liquid chromatography-quadrupole/electrostatic field orbit trap mass spectrometry（UPLC-Q-Orbitrap）.@*Methods@#The pork samples were extracted by ultrasound with acetonitrile，then the supernatant was centrifuged and purified by HLB solid phase extraction column. The analytes were separated by Waters HSS T3 column（100 mm×2.1 mm，1.8 μm）with gradient elution. Mass spectrometry adopted positive ion scanning and targeted SIM/dd-MS2 monitoring mode to complete the separation of analytes in samples and mass spectrometry analysis within 10 minutes. The chromatographic retention time and fragments in mass spectrometry were compared with prepared standards to determine whether the samples contained the antibiotics tested，then the positive samples were quantified.@*Results@#The 16 kinds of β-lactam antibiotics had good linear relationship in the range of 5-400 ng/mL（all the correlation coefficients >0.99）. The detection limits ranged from 0.08 μg/kg to 0.41 μg/kg，recovery rate ranged from 85.5% to 116.7%，and relative standard deviation（RSD）ranged from 3.6% to 12.8%. One of twenty pork samples detected was found penicillin G（28 μg/kg）and ampicillin（18.5 μg/kg）.@*Conclusion@#UPLC-Q-Orbitrap has high resolution and can reduce matrix interference to improve the accuracy. This method is simple，fast and efficient，thus can be used to screen and quantify β-lactam antibiotics in pork.
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Objective: A high-performance liquid chromatographic (HPLC) procedure with a fluorescence detector was developed to rapidly separate ?,?,?,?- tocopherol isomers in human serum Methods: The HPLC system consisted of Inertsil silica column (100-A, 3?m,4.6mm?250mm) and 7% (v/v) methyl-tert- butyl ether in n-hexane as mobile phase . Prior to HPLC, the serum sample wa deproteined by ethanol (BHT 0.0625%) and the tocopherol isomers were efficiently extracted in thei original isomeric conformations using n-hexane-ethyl acetate (5:1) in the presence of 2,6-bi-buty p-methylphenol (BHT). Result: The quantification limits, defined as the lowest quantitatively measurable concentration of the different compounds (ng/ml) are calculated according to the experiment:?-tocophero 1.0,?-tocopherol 1.0,?-tocopherol 0.5,?-tocopherol 0.5. The recovery rates are between 95%~105% Correlation coefficients are over 0.999 when the concentration is between 5 ng/ml~5 ?g/ml. Conclusion This technique is suitable for assay of tocopherol isomers in human serum at all ages.
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A method for the determination of B6-pyridoxamine (PAM), pyridoxal (PAL) and pyridoxine (POL) by RPLC was proposed. The procedure included the addition of 0.1M H2SO4 to the sample, hydrolysis for 30 min at 120℃, centrifuging, filtration and direct analysis by ODS Cl8 column. PAM, PAL and POL were completely separated, when the flow rate of the mobile phase (pH2.0-2.1) was 1.0-1.5ml/min. Quantitation by a fluorescent detector was performed with Exc: 293 nm and Em: 395 nm. The recovery ranged from 99 to 103% with CV 5.0-5.3%. The method was simple, rapid, sensitive and reproducible.