Introduction & Objective: The use of modern microextraction techniques for determination and evaluation of pollutants is progressively increasing nowadays. Needle trap microextraction (NTME) technique has privileges compared to the other techniques for sampling occupa-tional and environmental pollutants from air. In this study the application of NTD technique packed with polydimethylsiloxane as sorbent for determination of two organohalogen com-pounds (carbon tetrachloride and trichloroethylene) was investigated.

Material & Methods: In this experimental study NTDs were prepared with the same length of proposed sorbent and used after calibration of sampling pump. The parameters related to performance of NTD and proposed sorbent including temperature and relative humidity, sampling storage time and breakthrough volume were investigated. In analytical performances, the capability of NTD on time and temperature of desorption also carryover of analytes were assessed. Finally, the results for NTD microextraction e were compared to the NIOSH 1003 method.

Results: Results have shown that, temperature and relative humidity had effects on the per-formance of NTD and it's sorbent, and NTD contained PDMS showed better performance in the lower temperature and relative humidity at the range of assessment. The performance of NTD and it's sorbent for storage of sampled analytes was more than 95% of analytes mass after 4 days of sampling. The proposed technique also showed a good performance for de-sorption parameters and desorption temperature and time was 290°C and 4 minutes, respectively. After desorption, the carryover was also investigated and measured as 4 min. Relative standard division (RSD) for repeatability of method for NTD from different concentration levels of 1-250 µgL^-1 were 4.1-7.5%.

Conclusions: The NTD technique as an active sampling method with high enrichment factor showed a good performance for sampling and analysis of volatile organohalogen compounds in air. The low cost and rapid determination of compounds makes NTD a proper technique for indoor and outdoor monitoring of air pollution.