Negative Ion Chemical Ionization-Gas Chromatographic-Mass Spectrometric Determination of Residues of Different Pyrethroid Insecticides in Whole Blood and Serum

A new rapid and sensitive analytical method using negative ion chemical ionization-gas chromatography-mass spectrometry in selective ion monitoring mode has been developed for the determination of residues of different synthetic pyrethroid insecticides, allethrin, bifenthrin, cypermethrin, cyphonothrin, cyfluthrin, lambda-cyhalothrin, deltamethrin, fenvalerate, fenpropathrin, permethrin, prallethrin, and trans-fluthrin, in whole blood. The residues of pyrethroid molecules were extracted from the whole blood using a hexane and acetone (8:2, v/v) solvent mixture without separating the serum. The method was found sensitive to detect the residues of pyrethroids up to the level 0.2 pg/mL. Experiments conducted with the whole blood samples at the fortification level 1-100 pg/mL showed 91-103% recovery, whereas blood serum samples collected after the fortification of pyrethroids in whole blood showed 36-54% recovery. Recovery experiments conducted by direct fortification of pyrethroids in blood serum samples showed 96-108%. The applications of the analytical method was tested by analyzing 73 human blood samples collected from the population exposed continuously to different pyrethroid-based formulations. None of the blood samples showed residues of pyrethroids. The results were also confirmed by the detection of the appropriate amounts in a number of these samples, which had subsequently been spiked with known quantity of pyrethroids.