固相萃取-高效液相色谱-串联质谱法测定粮食中矮壮素和缩节胺残留量

粮食样品用甲醇-水(1+1)溶液超声提取,所得提取液通过Strata-X-C固相萃取小柱净化,用甲醇-0.2mol.L-1乙酸铵溶液(1+1)的混合液洗脱,将洗脱液旋转蒸发至近干,用乙腈-水(2+3)溶液溶解并定容至1 mL供测定。采用Aglient ZORBAX RX-SIL色谱柱(3.0 mm×100mm,1.8μm)分离,以乙腈和0.01mol.L-1乙酸铵溶液(含0.1%甲酸)按体积比20比80混合作为流动相,在0.3mL.min-1流量条件下进行洗脱。质谱测定中采用正离子电离方式,多反应监测扫描模式。矮壮素和缩节胺的质量浓度在0.2～10μg.L-1范围内与峰面积呈线性关系,检出限(3S/N)分别为0.02,0.05μg.kg-1。用标准加入法做回收试验,测得回收率在80.1%～104.7%之间,相对标准偏差(n=5)为2.5%～9.3%。

HPLC-MS/MS Determination of Residual Amounts of Chlormequat and Mepiquat in Grains with Solid Phase Extraction

Sample of grains was extracted with methanol-H2O(1+1) solution ultrasonically.The extract was purified by passing through the Strata-X-C SPE column and eluting with mixture of methanol and 0.2 mol·L-1 ammonium acetate solution(1+1).The eluate was evaporated rotationally to near dryness,and made up its volume to 1 mL with acetonitrile-H2O(2+3) solution.Aglient ZORBAX RX-SIL(3.0 mm×100 mm,1.8 μm) chromatographic column was used for separation,using a mixture of acetronitrile and 10 mmol·L-1 ammonium acetate solution(containing 0.1% of formic acid) mixed in ratio of 20 to 80 as mobile phase for elution(flow rate: 0.3mL·min-1).ESI with positive ionization mode and multiple reactions monitoring mode were used in the MS/MS analysis.Linear relationships between values of peak area and mass concentration of chlormequat and mepiquat were found in the same range of 0.2-10 μg·L-1,with detection limits(3S/N) of 0.02 and 0.05 μg·kg-1 respectively.Test for recovery was made by standard addition method,giving values of recovery and RSD′s(n=5) in the ranges of 80.1%-104.7% and 2.5%-9.3% respectively.