Rapid quantitative HPLC analysis of polyethoxylated nonionics

Abstract

AbstractA rapid quantitative HPLC method for alkylethoxylate was studied. According to theoretical considerations based on the plate theory, it was expected that alkylethoxylate could be separated to give one chromatographic peak regardless of the carbon number distribution in hydrophobic moiety and adducted number of ethylene oxide by using a back flush technique.As expected, a single peak with good shape for quantitative use was obtained. Quantitative analytical methods were developed for (i) unconverted alkylethoxylate in alkylethoxysulfate, and (ii) alkylethoxylate nonionics formulated with anionics in detergents.As anionics generally were retained less than alkylethoxylates under the condition in which ODS‐column and a methanolic aqueous eluent were used, a single peak for alkylethoxylates was obtained by back flushing after anionics were eluted from the column. In the case of a heavy duty detergent, an additional column was needed to remove the interferences owing to co‐existing more retained species.