Development and application of GC-MS method for monitoring of long-term exposure to the pesticide cypermethrin.

Cypermethrin (CPMN) is a synthetic pyrethroid used as an insecticide in large-scale commercial agricultural applications as well as for domestic purposes. In the present study a gas chromatography-mass spectrometry (GC-MS) based method was developed and validated for the quantitation of CPMN metabolites, 3-phenoxybenzoic acid (3-PBA) and cis- and trans- 3-(2,2-dichlorovinyl)-2,2-dimethyl-1-cyclopropane (cis- and trans- Cl2 CA). The developed method was applied for the monitoring of CPMN metabolites in hair of laboratory animals (rabbits) intentionally exposed per os to CPMN at 40 (low dose) and 80 (high dose) mg/kg weight/day for 16 weeks. The analytical method comprises three main steps: isolation of analytes from hair, analytes derivatization, and subsequent instrumental analysis by GC-MS. The limits of detection ensured by the method are 4.0, 3.9 and 1.0 pg/mg hair for cis-Cl2 CA, trans-Cl2 CA and 3-PBA, respectively. The instrument responce is linear (r(2)  > 0.99) in the investigated concentrations range from 25 to 1000 pg/mg. With and between-run precision as well as accuracy were estimated and found satisfactory. Analytes were efficiently isolated by solid-liquid extraction from hair with recoveries greater than 84.8% for cis-Cl2 CA, 87.2% for trans-Cl2 CA and 96.4% for 3-PBA. Rabbit's hair showed increasing levels for all metabolites (metabolites accumulation in a time and dose dependent manner) over time and in a dose-dependent manner. The developed experimental procedure could be used for biomonitoring of population exposure to CPMN.