Development of new SPME fibers by sol–gel technology for SPME-HPLC determination of organometals Original Research Article

Solid-phase micro-extraction (SPME), has advantages of simplicity, low cost, ease of use and rapid pre-concentration and extraction compared to other sample preparation techniques. The technique has found limited use in high performance liquid chromatographic applications because of the unavailability of fibers that are stable and durable in strong organic solvents. This study describes the preparation of fibers that are stable in strong organic solvents (xylene and methylene chloride) as well as acidic and basic solutions (pH 0.3 and 13) using the sol–gel process. The hydrolytic stability of these sol–gel-prepared SPME fibers towards organic solvents and high and low pH solutions can be attributed to the fact that the coating is chemically bonded to the surface of the fused silica substrate. These fibers have been subsequently used to extract organo-arsenic, organo-mercury and organo-tin compounds from aqueous solutions followed by separation using HPLC with UV absorbance detection. Under experimental conditions used, detection limits of 80, 412 and 647 μgl−1for triphenylarsine (Ph3As), diphenylmercury (Ph2Hg) and trimethylphenyltin (TMPhT), respectively, were obtained after extraction and HPLC separation. While these detection limits were comparable and/or slightly better than those obtained using commercial SPME fibers, the thinner coatings (resulting in faster extraction time) and the hydrolytic stability of the sol–gel fibers, towards strong organic solvents and high and low pH solutions, gave them superior characteristics when compared to commercially available fibers.