Cloud Point Extraction coupled to Micellar Electrokinetic Capillary Chromatography: an efficient alternative for the environmental monitoring of phenolic pollutants

PATRICIA WANDA STEGE; LORENA L. SOMBRA; GERMÁN ALEJANDRO MESSINA; LUIS DANTE MARTINEZ; ROBERTO A. OLSINA; MARIA F. SILVA

Santiago de Chile, Chile

Congreso; 3thLatin American Symposium on Biotechnology, Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology; 2007

Introduction of toxic pollutants can have a severe impact on many organisms in every ecosystem. p-Nitrophenol (PNP) is an important fine chemical intermediate, serving as a precursor of pharmaceuticals, pesticides, diesel fuel and gasoline exhaust. PNP has been selected as one of the persistent, bioaccumulative and toxic (PBT) chemicals by the US Environmental Protection Agency. On the other hand, p-aminophenol (PAP) is recognized as a serious environmental pollutant, and its target sites are blood and kidney. PAP is used as an intermediate in the production of medicines such as clofibrates and paracetamol and Hydroquinone (HQ) has a variety of uses principally associated with its action as a reducing agent and its water solubility and it is a major component in most photographic developers. It is also used as a raw material of herbicides, rubber antioxidants and dye stuffs. The purpose of the present study was to demonstrate the feasibility of the coupling of a cloud point methodology to Micellar Electrokinetic Capillary Chromatography (MECK) for the preconcentration-simultaneous determination of phenolic pollutants in samples of environmental interest. Extraction percentages higher than 90.5% were achieved when the procedure was carried out under the optimal experimental conditions. Consequently, the enrichment factor achieved for a 15 mL sample volume was: 200-fold (PONPE 7.5) and with 180-fold (PONPE 10). The LODs for the preconcentration of 15 mL sample volume, based on an S/N of 3 were 0.005 mg/L for PNP, 0.01 for PAP and 0.008 mg/L for HQ. The calibration graphs using the preconcentration system were linear with a correlation coefficient of 0.9997 (p-nitrophenol), 0.998 (p-aminophenol) and 0.9994 (hydroquinone) at levels near the detection limits up to at least 10 mg/L. The analytes under study were baseline separated in less than 17 min, giving separation efficiencies of up to 368029 (p-nitrophenol) average experimental electrophoretic plates (N). This procedure have advantages over those currently available including low cost, safety, feasibility for simultaneous determination and high capacity to concentrate a wide variety of analytes of widely varying nature with high recoveries and very high concentration factors. The results of this study clearly demonstrate the potentiality and versatility of this method, which could be applied to routine environmental monitoring.