Determination of Abamectin Residues in Grain by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry
A new analytical method has been developed for the simultaneous determination of abamectin residues such as abamectin,ivermectin and emamectin benzoate in grain. The samples of brown rice,wheat and corn were extracted with acetonitrile by an oscillator,cleaned up by acid alumina column,and analyzed by gradient ultra performance liquid chromatography-tandem mass spectrometry with electrospray ionization in positive mode( ESI+) using a UPLC BEH C18Column. The method was validated using fortified brown rice,wheat and corn. Mean recoveries of grain at four spiked levels( 10,50,100. 0 and 1000 μg / kg) were found between 87% and 109% with good precision( RSD 8%) for brown rice,wheat and corn. Mean recovery of within-laboratory reproducibility was between 97% and 107% with good precision( RSD 9%) for all the pesticides at the spiked level of 50 μg / kg. Limits of detection( LODs) for abamectin,ivermectin and emamectin benzoate in brown rice,wheat and corn were 0. 5,0. 5 and 0. 1 μg / kg,which are lower than the maximum residue limit( MRL) established by Chinese,Japanese and European legislation in grain. Good linear relationships were obtained in the range of 2. 0-64 μg / L for abamectin and ivermectin,and in the range of 0. 5-32 μg / L for emamectin benzoate with the correlation coefficient over 0. 997.