OPTIMIZATION OF SOLID-PHASE MICROEXTRACTION CONDITIONS FOR DETERMINATION OF PHENOLS

In solid-phase microextraction (SPME), sorbent-coated silica fibers are used to extract analytes from aqueous or gaseous samples. After extraction, the fibers are directly transferred to the injector of a gas chromatograph, where the analytes are thermally desorbed and subsequently separated and quantified. This is a fast and simple analytical technique, which does not require solvents. An SPME method based on poly(acrylate)coated fibers has been developed for the phenols regulated by U.S. EPA wastewater methods 604 and 625 and Ontario MISA Group 20 regulations. The method is capable of sub parts per billion detection limits of detection, and precision of 5-12 RSD, depending on the compound. Low pH levels and saturated salt conditions significantly increase the sensitivity of the method. Acid and salt conditions have been used to normalize the matrix of a sewage sample so that the amount extracted for heavier chlorinated phenols and nitrophenols is comparable to that for a spiked laboratory water sample. Chromatographic problems associated with free phenols have been overcome by simultaneous in situ derivatization and extraction of their acetates. The SPME of phenolics from the headspace over water has also been investigated. The results demonstrate suitability of the SPME approach to analysis of polar compounds.