Sampling free and particle-bound chemicals using solid-phase microextraction and needle trap device simultaneously.

The possibility of sampling the free and particle-bound concentrations of organic compounds was studied using two different sampling techniques at the same time: needle trap device (NTD) and solid-phase microextraction (SPME). In this study, a mosquito coil was used to produce gaseous (free) and particle-bound compounds. Allethrin, the active ingredient in mosquito coils, was chosen as the target analyte. Under the same sampling conditions, the amount of allethrin extracted from the mosquito-coil smoke was higher for the NTD compared to the SPME fiber, while the extracted amounts were almost the same for both devices when sampling gaseous samples of allethrin. These results can be explained by the fact that the SPME fiber can only extract free molecules (based on diffusion), whereas the NTD, an exhaustive sampling device, collects both free and particle-bound allethrin. Breakthrough for NTD and carryover for both NTD and SPME were negligible under the given sampling and desorption conditions.