食品用乙腈-水(3+1)溶液进行提取,经凝胶色谱、固相萃取柱净化后,用液相色谱-串联质谱法进行测定和确证,外标法定量。色谱分离用甲醇和甲酸-水(0.1+99.9)溶液以不同体积比混合为流动相梯度洗脱,采用负离子模式电喷雾离子源在多反应监测模式下进行检测。甲基磺草酮的质量浓度在0.01~0.2 mg·L-1范围内与其峰面积呈线性关系。以4种食品样品为基体,加入3种浓度水平的甲基磺草酮标准做回收试验,测得回收率在73.2%~100.6%之间;测定值的相对标准偏差(n=10)在4.1%~11%之间。

Foodstuff sample was extracted with acetonitrile-water (1+1) solution, and the extract obtained was purified by passing through gel permeation chromatographic (GPC) and solid phase extraction (SPE) columns. The eluate obtained was determined and identified by LC-MS/MS with external standard method for quantification. Mixtures of acetonitrile and HCOOH-H2O (0.1+99.9) solutions of various ratios were used as mobile phase in gradient elution and electrospray ionization source with negative ionization mode as well as multiple reaction monitoring mode were used in the MS/MS analysis. Linear relationship between values of peak area and mass concentration of mesotrione was kept in the range of 0.01-0.2 mg·L-1. Tests for recovery were made by addition of standard mesotrione solution at 3 different concentration levels to 4 kinds of foodstuff as matrixes, values of recovery found were in the range of 73.2%-100.6%, with values of RSD′s (n=10) in the range of 4.1%-11%.