Chiang Mai Journal of Science

 A gas chromatographic-electron capture detection (GC-ECD) method was developed for determinating six synthetic pyrethroids insecticides (i.e. cyhalothrin, permethrin, cyfluthrin, cypermethrin, fenvalerate, and deltamethrin) which have been widely used in fruit orchards and vegetable growing.  The synthetic pyrethroid insecticides were extracted using dichloromethane and cleaned up by loading onto the graphitized carbon cartridge.  Limit of detection (LOD) ranged from 1 to 5 ng g^-1 and limit of quantitation (LOQ) ranged from 2.5 to 10 ng g^-1. The relative standard deviation (RSD) of intra-batch and inter-batch ranged from 1.8 to 7.4% and 8.9  to 15.7%, respectively.  Recoveries at spiked levels (5, 10 and 50 ng g^-1.) ranged from 96.8-109.3%, 86.5-96.9 % and 83.8-98.4%, respectively. The developed method was successfully applied to quantify pyrethroid residues in fruit and vegetable samples from Chiang Mai province, northern Thailand. All samples had detectable levels of at least one synthetic pyrethoid insecticide residue.   This developed method is practical for analysis of six synthetic pyrethroid insecticide residues, especially for screening of large quantities of samples because of its short extraction time.  Moreover,   GC-ECD which is a typical equipment in organic trace laboratory was successfully employed and provided practical achievement of sensitivity.