ABSTRACT
A novel method for simultaneous detection of mycotoxins (e.g.,aflatoxin B1) or their metabolic residues in animal plasma with impurity adsorption purification followed ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed.Extraction of mycotoxins and their metabolites from animal plasma sample was performed with 0.1％ formic acid-acetonitrile solution after addition of sodium chloride and hydrous magnesium sulfate.The extract was then dehydrated and purified with hydrous magnesium sulfate,C18,primary secondary amine,and alumina-A.3 mL of the supernatant was evaporated and re-dissolved with 0.5 mL of 0.1％ formic acid aqueous solution/acetonitrile (70∶ 30,V/V) for UPLC-MS/MS detection.The analytes were separated by a C18 column utilizing gradient elution with 0.1％ formic acid aqueous solution containing 0.5 mmol of ammonium acetate and 0.1％ formic acid-methanol solution,and finally detected by tandem mass spectrometry in positive/negative ESI mode.Identification and quantification were achieved by LC-MS/MS with multi-reaction monitoring (MRM).Good linearity in response was obtained in the analytes concentration range of 0.05-100 ng/mL with correlation coefficients larger than 0.99.The limits of quantification (S/N=10) were around 0.05-0.5 ng/mL.The recoveries of mycotoxins and their metabolites spiked in blank plasma samples were in the range of 62.0％-116.4％,with relative standard deviations (RSDs) less than 19.0％.
ABSTRACT
A rapid high-throughput method for the determination of 26 mycotoxins involving multifunctional cleanup column coupled with liquid chromatography-tandem mass spectrometry ( LC-MS/MS) was developed and validated for the determination in feedstuffs. The feedstuff samples were extracted by ultrasonic treatment for 1 hour and the extraction solvent was acetonitrile/water/formic acid (84:15. 9:0. 1, V/V). 1 mL of the supernatant layer was purified by a commercial Mycospin 400 multifunctional cleanup column, then dried and re-dissolved by 0. 25 mL water/methanol/formic acid (95:4. 9:0. 1, V/V) in a vial for injection into the LC-MS/MS system. Chromatographic analyses were carried out on a reversed phase C18 column and using a gradient elution with 0. 1% formic acid aqueous solution and 0. 1% formic acid methanol solution. The mass spectrometer was operated in a multiple reaction monitoring ( MRM) mode that selected one precursor ion and two product ions for each target compound. Validation studies were carried out in maize and soybean meal as representative matrixes. The most target compounds had different level of matrix effects. So, matrix-matched calibration was adopted for quantification. Mean recoveries from spiked samples at three levels ranged from 61 . 9% to 119 . 5% with relative standard deviations of 0 . 8%-18 . 6%. Limits of quantification ranged from 0. 5 μg/kg to 25 μg/kg.
ABSTRACT
Two kinds of β2-agonistresidues in sheep plasma and urine were disposed by enzymolysis and organic solvent extraction pretreatment methods, and UPLC-MS/MS was used for the qualitative and quantitative analysis. Detection results were compared to study the influences of two pretreatment methods. The experimental results showed that more than 95% of Ractopamine and 40% of Salbutamol exist in the conjugated form in sheep plasma. The detection results of 2 kinds of β2-agonist residues were significantly enhanced when adding β-glucuronidase/aryl sulfatase. The experimental repeatability is very poor ( RSD>40%) when the enzymolysis was not carried out. There were 57% of Ractopamine and less than 1% of Salbutamol exists in the conjugated form in sheep urine. Enzymolysis pretreatment method was useful for the Ractopamine residues determination in urine, and Enzymolysis pretreatment method was useless for Salbutamol determination in urine. Matrix effect of plasma was less than the effects of urine. The influence of organic solvent extraction pretreatment method on the detection results was unremarkable, and there was the possibility that organic solvent extraction could lead partial loss of target compound in extraction process. However, it did not influence the detection results by using internal standard calibration.