Determination of phenolic compounds in industrial wastewaters by gas chromatography after extraction and preconcentration by microextraction procedure

This paper presents an efficient, simple, and fast method for the derivatization, extraction, and preconcentration of several phenolic compounds (phenol, o–, m– and p–cresol, 4–chlorophenol, and 2–nitrophenol) from wastewater samples and analysis of those samples by gas chromatography–flame ionization detection. In this method, initially the phenolic compounds are derivatized with acetic anhydride in an alkaline pH. In the following, the derivatized analytes are extracted into mL–volume of acetonitrile during homogeneous liquid–liquid extraction and further enrichment of the analytes are accomplished by their extraction into µL–volume of 1,1,2–trichloroethane through dispersive liquid–liquid microextraction step. Effective parameters controlling the performance of the proposed method such as type and volume of derivatization agent and catalyst, type and volume of extraction/disperser solvent in homogeneous liquid–liquid extraction, and type and volume of extraction solvent and salt addition in dispersive liquid–liquid microextraction are optimized. Under optimum conditions linear range of the proposed method was obtained 0.7–4000 µg L–1. Limits of detection and quantification were in the ranges of 0.07–0.20 and 0.23–0.70 µg L–1, respectively. Enrichment factors and extraction recoveries were ranged from 220 to 440 and 44 to 88%, respectively.