RESUMO
The monitoring of Phosdrin (mevinphos; insecticide) from foliage and foliage extracts was achieved by an aspiration-type ion mobility spectrometer. This technique is based on ion mobility, which is proportional to the molecular weight, shape, and charge. The operation principle of the ion mobility spectrometer is to measure mobility distribution changes of product and reactant ions. This technique can measure positive and negative ion clusters at the same time in six different measuring electrodes. Each measuring electrode detects a different portion of the ion mobility distribution formed within the cell's radioactive source. The pattern recognition used is based on differences in the gas profiles for different compounds. This study shows that an ion mobility spectrometer can be used to monitor Phosdrin from foliage without the need for any time-consuming extraction procedure. The responses for Phosdrin-containing and background (control) samples were easily separated from each other. The responses declined as a function of time in the positive and sum response channels. In addition, the sum of the absolute values of signals at six measuring channels (sum response) were linearly proportional to the concentration of Phosdrin. Just before application (i.e., in background), this value was 41 bits, whereas these values were 10-fold, 11-fold, 8-fold, 6-fold, 5-fold, and 3.5-fold at the time points 4, 8, 11, 24, 50, and 72 hours after the spraying of Phosdrin.
