An assessment of a liquid-liquid extraction procedure for the gas chromatographic analysis of chloroform in algal media

Abstract

The purpose of this study was to evaluate the effects of several factors which might alter the analysis of chloroform in aqueous samples by the liquid-liquid extraction (LLE) method developed by Glaze at North Texas State University. A Bendix gas chromatograph (GC) was used. The factors examined were the effect of the ionic strength of the sample on the extraction method, the relative extraction efficiency when three pentane-to-sample ratios were used, the change in the response of the GC to a set of samples during a several hours lengthy analysis, the precision of the data obtained by the analysis procedure, and the precision of analyses of aqueous chloroform standards made from one set of secondary standards. These factors were examined to aid in the development in this laboratory of an analysis program to study the role of algal extracellular metabolites as trihaloomethanes precursors.

Ionic strength up to 0.0116 (strengths of algal media) did not affect the results. Few differences in the extent of linearity or extraction efficiency were detected when pentane-to-sample ratios of 1:1, 2:1, or 1:2 were used. The extraction efficiencies of the three ratios deviated 11 percent of their mean, with four values not included. The GC's response to a set of samples analyzed at the beginning and end of a nine-to-twelve hour experiment may change significantly. Standards prepared in pentane did not change during the test period. Four replicate analyses of the same sample were found to be highly precise.