Method for quantification of insecticide in mosquito netting using ion implantation and ToF-SIMS analysis

Abstract

Permethrin is used worldwide as a mosquito insecticide for netting and fabric. Permethrin is a contact insecticide so only the permethrin on the surface can directly impact the mosquito. Therefore, knowledge of the surface concentration of the insecticide is essential to measure the effectiveness of the treated material. Time-of-flight secondary ion mass spectrometry analysis of permethrin showed Cl− as the predominant species in the negative ion mass spectrum. The netting material in this study is composed of high density polyethylene (HDPE). Ion implantation was used to place a known amount of chlorine into the netting material, sheet HDPE, and silicon samples. Depth profile analysis of the implanted samples showed distinct chlorine implant profiles, with the silicon sample used to verify implant dose. Quantification and detection limit for chlorine have been obtained for HDPE sheet and netting. The chlorine detection limit in HDPE is approximately 2 × 1018 atoms/cm3, and the chlorine concentration in netting fibers ranged from 4 × 1019 to 1.2 × 1020 atoms/cm3, which compares very well with the amount of insecticide put into the netting during fabrication. The results make possible the study of insecticide content at the surface and in the bulk of the netting. Investigation is in progress for the effect of washing mosquito nets on surface chlorine concentration.