MICROEXTRACTION OF CHLORINATED BENZENES AND SELECTED ORGANOCHLORINES FROM ENVIRONMENTAL WATER

This study describes the extraction of CBs and OCs from water by conve ntional means using only a few millilitres of solvent. The parameters investigated were volume of n-hexane versus time of extraction. The re sults clearly show several alternatives to the analyst, i.e., smaller volume-longer time or larger volume-shorter time. Typically, good reco veries could be achieved with as little as 5 mL of n-hexane in a singl e step 10-minute extraction of a one-litre water sample, bur more cons istent results were obtained with environmental water with two success ive extractions using 2 mt of solvent and a few drops of acetone to re duce emulsions. For instance, average recoveries of 83.29% and 87.75% were obtained for CBs and OCs, respectively, in a multi-residue analys is of environmental water comprising 22 components at the 0.01-0.25 pp b level. Thus, the microextraction approach looks very promising as an alternative to the lengthy and often more costly traditional liquid-l iquid extraction approach for the analysis of CBs and OCs from environ mental water. In fact recoveries are better for volatile analytes such as low molecular weight chlorobenzenes because the evaporation step i s eliminated. Also, precision of the data for individual congeners is better.