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.