In tube solid phase microextraction: A promising technique for extraction ultr-trace amounts of organic and inorganic pollutants from aqueous solutions

Sample preparation is important for isolating desired components from complex matrices and greatly influences the reliability and accuracy of their analysis. Solid phase microextraction, which integrates concentration,extraction and sample introduction in to a single step, was first introduced by Pawliszyn and et al. [1]. To further enhance the extraction capacity and improve the stability of the fiber in SPME methods, in-tube solid-phase microextraction (IT-SPME) as a form of capillary microextraction (CME) was developed in 1997 [2]. Since the length and surface area of the coating in IT-SPME method is much higher than that used in fiber SPME, this method can provide greater extracting phase loading, increase sample capacity and improveextraction sensitivity. In addition, IT-SPME offers easy automation of the extraction process by on-line coupling to HPLC. In general, the majority of the commercially available IT-SPMEs are mostly devoted to fused silica capillaries with different polymeric coatings. However,the utility of conventional capillary columns is limited by their low extraction efficiency because of the large breakthrough volume and the small amount of adsorbent phases, low stability, and, in some cases, the long extraction times involved due to the slow diffusion of the analytes from the sample to the capillary coating. Considerable efforts have been focused on developing new adsorbent phases, such as fiber packed, sorbent-packed, and rod-type monolith capillaries, to improve the extraction efficiency, stability, and selectivity [3]. In the present review electrochemically deposition of different coatings like as conducting polymers, lyered double hydroxides and various composits on the inner surface of a stainless-steel tube as the unbreakable substrate will be discussed. Coating of surface of metal beads, wires, etc with proper sorbents by electrochemical methods and packing of them into stainless-steel tube will be investigated. Also on line coupling of IT-SPME with HPLC-UV, atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry will be presented. Applications of IT-SPME and electrochemically controlled in-tube solid phase microextraction (EC-IT-SPME) for extraction and analysis of organic and inorganic species in aqueous matrices will be discussed. Finally IT-SPME’s potentials and limitations and its future view will be investigated [4-7].