ANALYSIS OF FORMIC AND ACETIC ACID IN RAIN WATER BY CAPILLARY ELECTROPHORESIS

摘要

A simple technique is described for the routine capillary electrophoretic determination of formic and acetic acid in rain water. These acids were determined simultaneously in approximately 6 min using a carrier electrolyte containing 10 mM phosphate and 0.5 mM myristyltrimethylammonium bromide (MTAB) as electroos-motic flow (EOF) modifier at pH 6.5 and direct UV detection at 185 nm. The method is quantitative, with recoveries in the 99-101% range and linear up to 5 mg L~(-1). The precision is better than 2.1% and the procedure shows the appropriate sensitivity, with detection limits between 0.042 and 0.055 mg L~(-1). The proposed method was successfully employed for the determination of formic and acetic acid in 57 rain water samples, collected from October 2000 to February 2001 in four different sampling stations located in Galicia (NW Spain), by direct sample injection after filtration.