Extraction media used in needle trap devices-Progress in development and application.

Analysis of trace compounds in complex matrices requires a preliminary step of sample preparation. From among widely used methodologies, microextraction techniques have become increasingly important as they tend towards being environmentally friendly. The needle trap (NT) extraction is a relatively new and promising technique which combines sampling, sample preparation and sample introduction. The core of the needle trap device is a suitable sorbent material packed inside the needle, that determines selectivity and efficiency of the method. In recent years, the effort towards improvement of needle trap extraction performance has led to development of new extraction media with higher selectivity and better adsorption properties, which may facilitate preconcentration of the target analytes. In this work, we present a review on the trends in development of sorbent materials used in the needle trap device including fibrous media, commercially available materials as well as sorbents prepared for special applications. This review also describes recent developments in the needle trap devices such as needle geometries, sorbent packing procedure and sampling methodologies. Comparison of needle trap extraction and solid phase microextraction (SPME) is presented to demonstrate the robustness of the former.