液相色谱-串联质谱法快速测定植物源性食品中的百草枯

Determination of paraquat residue in plant-derived foodstuffs by high performance liquid chromatographytandem mass spectrometry

建立了水果、蔬菜、豆类和粮谷中百草枯残留的高效液相色谱-串联质谱(HPLC-MS/MS)分析方法。用水提取样品中的百草枯,弱阳离子交换(WCX)固相萃取柱(SPE)净化。采用CAPCELL PAK ST色谱柱(150 mm×2.0mm),乙腈-10 mmol/L乙酸铵水溶液(用甲酸调至pH 4.0)为流动相,以电喷雾离子源正离子模式多反应监测(MRM)定性、定量测定百草枯。百草枯在0.01～0.1 mg/L范围内峰面积与质量浓度呈线性关系,相关系数为0.993。在空白样品中添加百草枯,测得方法的回收率为84.0%～106.0%,相对标准偏差(RSD)为7.8%～18.8%。果蔬和粮谷样品中百草枯的定量限分别为0.01 mg/kg和0.05 mg/kg,满足各国残留限量要求。

A sensitive and selective method is presented for the determination of paraquat residue in fruits, vegetables, beans and grain by high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS）. Paraquat in samples was extracted with water and cleaned-up with a weak cation exchange （WCX） column to obtain an extract suitable for analysis using HPLC-MS/MS. The paraquat was separated by a CAPCELL PAK ST column （ 150mm×2.0 mm） and with acetonitrile-10 mmol/L ammonium acetate solution （ adjusted to pH 4.0 by formic acid） as the mobile phase, and multiple reaction monitoring （MRM） was used with electrospray ionization in the positive ion mode. The calibration curve was linear between the peak area and the mass concentration of paraquat from 0.01 to 0.1 mg/L with the correlation coefficient of 0. 993. Recoveries of paraquat spiked in samples at three levels ranged from 84.0% to 106.0% with the relative standard deviations of 7.8% - 18.8%. The limits of detection （LODs） of paraquat were 0. 01 mg/kg in fruits and vegetables and 0.05 mg/kg in beans and grain. The LODs can meet the requirements of international maximum residue limit.