Quantification of High Concentration Sodium Alkylbenzenesulfonates Standard Solution Using Relative Sensitivity Based on Molar Absorption Coefficient

Abstract

Sodium alkylbenzenesulfonates (ABS) have been used as reference materials for the analysis of anionic surfactants in tap and environmental waters. In this study, we developed a method to quantify the total amount of benzenesulfonic acids in solution based on the molar absorption coefficients of the analogues. After confirming the same absorption spectra among the analogues, we quantified LAS and ABS at approximately 1000 mg L⁻¹ using linear dodecylbenzenesulfonic acid (12C-LAS), then we compared these results with those obtained by quantitative ¹H NMR. To validate ABS quantification, we compared results from two laboratories. The results for all target compounds agreed with the reference values within a range of approximately 2 %, and the difference between the two laboratories was approximately 1 %. Considering concentration dependence and peak shapes as sources of uncertainty, the relative value of the expanded uncertainty was less than 6 % for the alkylbenzenesulfonate standard solution at approximately 1000 mg L⁻¹, which should be acceptable for routine analyses of anionic surfactants in tap and environmental waters.