Gas chromatographic method for the analysis of permethrin isomers in some forestry substrates

Abstract

A simple and specific method was developed to quantitate individually the cis and trans isomers of permethrin present in forestry substrates at residue levels. Permethrin isomers were extracted from the substrates with hexane, followed by acetonitrile partition, purification by Florisil^®, Nuchar SN^® charcoal‐cellulose microcolumn adsorption chromatography, elution by dichloromethane and eventual quantification by gas‐liquid chromatography with electron capture detector (GLC‐EC) with a glass column (1.2 m × 2 mm i.d.) packed with 6% QF‐1 + 3% DC‐200 on 80–100 mesh Chromosorb W‐HP. The method exhibits good recovery (>80%) and reproducibility (SD <10% and C.V. <12%) for both the isomers of permethrin at fortification levels ranging from 0.05 mg/kg to 1.00 mg/kg in conifer foliage, leaf litter, forest soil, sediment and fish and from 0.05 μg/kg to 1.00 pg/kg in natural waters. Limits of detection and quantification levels are 0.01 and 0.02 mg/kg respectively for terrestrial substrates, fish and sediment and 0.01 and 0.02 μg/kg for natural waters.

Key words:

• Permethrin
• residue analysis
• forestry substrates
• microcolumn cleanup