OPTIMIZATION OF SOLID-PHASE MICROEXTRACTION CONDITIONS FOR DETERMINATION OF PHENOLS

In solid-phase microextraction (SPME), sorbent-coated silica fibers ar e used to extract analytes from aqueous or gaseous samples. After extr action, the fibers are directly transferred to the injector of a gas c hromatograph, where the analytes are thermally desorbed and subsequent ly separated and quantified. This is a fast and simple analytical tech nique, which does not require solvents. An SPME method based on poly(a crylate)coated fibers has been developed for the phenols regulated by U.S. EPA wastewater methods 604 and 625 and Ontario MISA Group 20 regu lations. The method is capable of sub parts per billion detection limi ts of detection, and precision of 5-12 RSD, depending on the compound. Low pH levels and saturated salt conditions significantly increase th e sensitivity of the method. Acid and salt conditions have been used t o normalize the matrix of a sewage sample so that the amount extracted for heavier chlorinated phenols and nitrophenols is comparable to tha t for a spiked laboratory water sample. Chromatographic problems assoc iated with free phenols have been overcome by simultaneous in situ der ivatization and extraction of their acetates. The SPME of phenolics fr om the headspace over water has also been investigated. The results de monstrate suitability of the SPME approach to analysis of polar compou nds.