DETERMINATION OF BRANCHED AND LINEAR ALKYLBENZENE SULFONATES (BAS AND LAS) IN WATER USING HPLC

Analytical methodology has been developed for the simultaneous determination of branched and linear alkylbenzene sulfonates (BAS and LAS) in river water and wastewater samples. The samples were purified and concentrated by solid phase extraction, followed by HPLC separation and quantification using a C18 column. The LAS homologues were well separated with prominent peaks corresponding to the different alkyl groups with carbon chainlengths from C-10 to C-14. The elution of BAS shows a slightly broadened major peak with the same retention time as the C-11 peak of LAS. The C-12 peak, with no significant contribution from BAS components, has been chosen for the direct determination of LAS whereas the concentration of BAS can be calculated from the composite peak height of BAS after correcting for the C-11 contribution from LAS. The method has been applied for the determination of the levels of specific LAS and BAS in some river water and wastewater samples. Comparison with the anionic surfactant concentrations measured in terms of the standard MBAS (methylene blue active substances) values is presented.