Simultaneous detection for residue of imidacloprid and nitenpyram in cowpea using HPLC method

The maximum absorption wavelength of imidacloprid and nitenpyram detected by UV spectrophotometer were 270 nm and 246 nm. To get optimum retention time and separation,the mobile phase should be acetonitrile and water( V / V,3 ∶ 7). Standard curves of two pesticides were developed,which fit a linear regression ranging from 0. 05 to 5 μg·mL- 1. After extracted by homogenate with acetonitrile and purified by C18 SPE column,the recovery rates of the two pesticides were 75% ~ 110% at the levels of 0. 1mg·kg- 1,0. 5mg·kg- 1and 1. 5mg·kg- 1with a RSD less than 5%,which showed a good accuracy and stability. This method with a limit of quantification( LOQ) of 0. 01μg·g- 1could be used in the practical detections.