Investigation and optimization of particle dimensions for needle trap device as an exhaustive active sampler

Various needle trap devices (NTDs) with different designs have been developed during the past decade. A theoretical model on the fundamentals of the NTD was recently proposed, which employed the theory of frontal (gas-solid) chromatography to describe the sampling process. In the current work, different types of sorbent particles with different dimensions were packed into the needle as the adsorbent. The effects of particle dimensions, which would affect the packing density and consequently affect the capacity, the extraction efficiency and desorption efficiency of the NTD were experimentally investigated and the proposed theory was validated. The results demonstrated that NTDs packed with small particles possess higher extraction capacity and efficiency but much higher resistances to flow as well. The higher resistance did not necessarily result in poor desorption efficiency. The observed relationships among those physical parameters provide valuable guidance on how to design a NTD with high performance for future applications.