|Chlorpyrifos is one of the most-widely used active ingredients for pest control products in the world. It is used to protect a number of important agricultural crops, such as corn, citrus, alfalfa, peanuts, and others from pest insect attack. In California ~1.43 million pounds of chlopyrifos were used in 2007 of which 750,000 were used in Fresno, Kern and Tulare County. Occupational exposure occurs in workers involved in the manufacturing of chlopyrifos, pest control applications, and farmers. The pyrethroids are used as insecticides to control mosquitoes. Pyrethroids have been linked to disruption of endocrine system which can adversely affect reproductive and sexual development, interfere with immune system and increase chances of breast cancer. |
The chlorpyrifos and pyrethroids, like all organophosphate (OP) pesticides, act as a competitive inhibitor of acetyl cholinesterase. Unfortunately, high doses affect humans especially vulnerable population such as children. To access the exposure, California Environmental Contaminant Biomonitoring Program requires that our laboratory develop techniques to quantify the metabolites of these pesticides in human urine samples.
The 3, 5, 6 trichloro-pyridinol (TCPy) is a specific metabolite for chlorpyrifos and 3-phenoxy benzoic acid (3-PBA) is a specific metabolite for pyrethroids. We have validated a method to analyze these metabolites in urine. The analytes are extracted and concentrated from the urine matrix using solid phase extraction cartridges, separated through high pressure liquid chromatography, and analyzed on a triple quadrupole mass spectrometer using API 5000 LC-MS/MS using heated electrospray (H-ESI) technique. Different MRM transitions were evaluated for TCPy test. The detection limit for TCPy is 0.14ng/mL and for 3-PBA is 0.16ng/mL. The analytical precision for TCPy is 17.8% at 16ppb, 7.8% at 8.0ppb, and 7.6% at 16.0ppb. The analytical precision for 3-PBA between-day variation (CV) is 14.0% for 1.0 ppb, 10.8% at 8.0 ppb, and 11.0% at 16ppb concentration. The extraction recoveries of TCPy ranged from 98-110% and for 3-PBA from 94-116%.