Analysis of permethrin treated fabric using ToF-SIMS

Abstract

Recent studies have shown that it is possible to use ToF-SIMS to identify and quantify mosquito insecticides, such as permethrin and deltamethrin, on mosquito netting. The insecticide in those studies was incorporated in the netting fiber. Permethrin treated fabric is in common usage to provide mosquito repellent clothing and is the only approved insecticide for apparel. The insecticide is applied to the fabric and will no longer be effective after a certain number of washing cycles. ToF-SIMS analyses have now been conducted on fabric composed of nylon and cotton before washing and after 10 and 30 washes to measure the reduction in insecticides. The results show a significant decrease in the insecticide between 10 and 30 washes. The 30 washes sample was known to be no longer effective against mosquitoes. ToF-SIMS was also able to differentiate cotton and nylon fibers. A cross-sectional analysis of cryomicrotomed samples showed the distribution of the insecticide in the individual fibers. The insecticide was found to penetrate completely through the fibers during its application. After ten washes, the insecticide was depleted more rapidly in the cotton than the nylon fibers. The results have implications for the number of acceptable washes for mosquito repellent fabric.