微波辅助萃取-液相色谱-串联质谱法测定植物源产品中的阿维菌素B1a残留量

Determination of Avermectin B1a Residues in Plant-originated Foodstuffs by Microwave Assisted Extraction-Liquid Chromatography Tandem Mass Spectrometry

建立了植物源产品茶叶、粮谷、中药材中阿维菌素B1a残留量的液相色谱–串联质谱(LC–MS/MS)测定方法。样品用丙酮–二氯甲烷(体积比1∶1)微波辅助提取,提取液经石墨化炭黑/氨基(Carb/NH2)固相萃取小柱净化。采用Hypersil Gold C18色谱柱(150 mm×2.1 mm,5μm),乙腈–2.5 mmol/L乙酸铵水溶液为流动相,以电喷雾电离正离子(ESI+)、多反应监测模式(MRM)定性、定量测定阿维菌素B1a,采用基质标准曲线外标法定量。在5～100μg/L范围内,阿维菌素B1a的峰面积与质量浓度呈线性关系,相关系数大于0.998,方法的检出限(S/N>3)为5μg/kg,定量限(S/N>10)为10μg/kg。取有代表性的绿茶、小麦、丹参阴性样品进行加标回收试验,在10,50μg/kg加标水平下,回收率为75%～87%,相对标准偏差为4.04%～6.38%(n=5)。该法提取效果好、净化较彻底,灵敏度满足国内外限量标准的要求,适合复杂基质植物源产品中阿维菌素B1a残留量的测定。

A microwave assisted extraction-liquid chromatography-tandem mass spectrometry method for the determiantion of avermectin B1a residues in tea, cereals and Chinese herbal medicine was developed. The sample was extracted by microwave assisted extraction with acetone-dichloromethane（volume ratio was 1 ： 1） as solvent, the extract was cleaned up by Carb/NH2 SPE column. The separation was performed on a Hypersil Gold CIS column（150 mm × 2.1 mm, 5 μm） and with the gradient elution of acetonitrile and water （containing 2.5 mmol / L ammonium acetate）. Avermectin B1a was determined in the mode of electrospry positive ionization （ESI＋） and multiple reaction monitoring（MRM）. The quantification was carried out by matrix-matched external standard curve, the calibration curves showed good linearity in the concentration range of 5-100μg/L and the correlation coefficient was more than 0.998. The limit of detection（S/N 〉 3） was 5 μ g/kg and the limit of quantification （S/N 〉 10） was 10 μg/kg. The recoveries in green tea, wheat and danshen samples at spiked levels of 10, 50 μ g / kg ranged from 75% to 87%, with the relative standard deviation of 4.04% - 6.38%（n=5）. The method established has advantages in extraction and purification and is sensitive enough in meeting the requirements of maximum residue limit （MRL） of avermectin B 1 a. The method is suitable for determination of avermectin B 1 a in plant-originated foodstuffs with complex matrix.