Development and application of needle trap devices

Needle trap devices (NTDs), like solid-phase microextraction (SPME) fibers, represent a new approach to one-step, solvent-free sample preparation and injection. New NTDs, packed with divinylbenzene (DVB) or Carboxen 1000 particles, are prepared, characterized, and used for benzene, toluene, ethylbenzne, and xylene (BTEX) sampling in our laboratory. This paper describes optimization parameters, performance evaluation, and application of NTDs for the analysis of a BTEX mixture from air. For active sampling, a sampling flow rate is an essential optimization parameter. Using a very small amount of sorbent particles (less than 1mg DVB or Carboxen), 1.9 mL/min was the highest sampling flow rate that could be used with no breakthrough of any BTEX components. A single NTD was used to study breakthrough volumes (BTVs) and the breakthrough volume was proportional to the quantity of sorbent packed inside the needle. The Carboxen-packed NTD showed higher BTVs for all BTEX compared to the DVB-packed NTD. The performance of home-made NTDs was evaluated at different sampling flow rates, storage times, and for reusability. Finally, DVB packed NTDs were used to sample and analyze a BTEX mixture from permanent marker fumes, mosquito coil smoke, and at various points in the interior of a house. A very low concentration (10 pg/mL) of toluene was detected in the garage.