Dissipation of diethyl aminoethyl hexanoate (DA-6) residues in pakchoi, cotton crops and soil.

QuEChERS procedure and acetonitrile extraction, oscillation and ultrasonic procedure followed by GC-MS and LC-MS/MS (QqQ) detections were established for determination of diethyl aminoethyl hexanoate (DA-6) residues in pakchoi, cotton leaf, cotton seed and soil. At concentration levels of 0.005-1 mg kg(-1), recoveries were in the range of 80.5%-103.3%, with a RSD less than 14.2%. The LOQs of methods were 0.005, 0.003, 0.005 and 0.001 mg kg(-1) for the pakchoi, cotton leaf, soil and cotton seed samples, respectively. DA-6 was applied in supervised field trials at GAP conditions to pakchoi and cotton. It was found that the dissipation half-lives of DA-6 were 5.4-8.2 days and 1.1-2.2 days and 1.5-1.9 days in cotton crop, pakchoi and soil respectively. At harvest, no detectable residues (<LOD) were found in cotton samples. However, residues was detected in pakchoi (0.007-0.013 mg/kg) in Beijing and soil (0.008-0.014 mg/kg) in Changsha in 2008.