超高效液相色谱-串联质谱法测定草莓中嘧菌酯的残留量

Determination of Azoxystrobin Residue in Strawberries by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

称取样品10.00g,加入20.00mL乙腈,高速匀浆2min后,用滤纸过滤,滤液收集到装有5g氯化钠的100mL具塞量筒中,盖上塞子,剧烈振荡2min,静置30min。取上清液10.00mL加入已经过5mL乙腈-甲苯(3+1)混合液预淋洗的Carbon/NH2固相萃取小柱,收集淋洗液,用20mL乙腈-甲苯(3+1)混合液分4次洗脱,合并淋洗液,于40℃水浴蒸发至近干,用甲醇(1+1)溶液定容至5.00 mL,旋涡混匀后,过0.22μm滤膜。滤液经Waters XBridge C18色谱柱(3.0mm×50mm,3.5μm)分离,以甲醇、乙腈和0.1%(体积分数)甲酸溶液为流动相进行梯度洗脱,质谱分析中采用电喷雾正离子源和多反应监测模式,以外标法定量。嘧菌酯质量浓度在0.001～0.10mg·L^(-1)与定量离子峰面积呈线性关系,检出限(3S/N)为0.10μg·kg-1。方法用于测定草莓中的嘧菌酯残留,加标回收率为78.0%～95.2%,测定值的相对标准偏差(n=6)小于7.0%。

The sample(10.00g)was added into 20.00 mL of acetonitrile,and the mixture was homogenized for 2 min at a high speed,and filtered with a filter paper.The filtrate was collected into a 100 mL cylinder containing 5g of sodium chloride,and the cylinder was covered with a stopper and shaked vigorously for 2 min.After standing for 30 min,10.00 mL of the supernatant was taken and purified with a Carbon/NH2 solid phase extraction cartridge,which had been pre-rinsed with 5mL of acetonitrile-toluene(3+1)mixture.The eluent was collected,and the cartridge was eluted with 20 mL of acetonitrile-toluene(3+1)mixture in 4portions.The eluent was combined and evaporated to near dryness in a water bath at 40 ℃.The residue was made up to a volume of5.00 mL with methanol(1+1)solution,and then the solution was vortexed well and then passed through a 0.22μm filter membrane.The filtrate was separated on a Waters XBridge C18column(3.0 mm×50 mm,3.5μm),with methanol,acetonitrile and 0.1%(volume fraction)formic acid as mobile phase for gradient elution.Electrospray positive ion source and multiple reaction monitoring mode were used for mass spectrometry analysis.External standard method was used for quantification.Linear relationship between values of the quantitative ion peak area and the mass concentration of azoxystrobin was obtained in the range of 0.001-0.10mg·L-1,with the detection limit(3S/N)of 0.10μg·kg^-1.The proposed method was applied to determination of azoxystrobin residues in strawberries,giving values of recovery obtained by standard addition method in the range of 78.0%-95.2%,and RSDs(n=6)less than 7.0%.