Abstract
Trace amounts of sodum alkylbenzenesulfonate (LAS) in river waters and sediments were determined by high-performance liquid chromatography (HPLC). The dried sediments were refluxed and extracted with methanol-benzeme mixture. After the concentration of the extract the residue was dissolved in hot water, and methylene blue active substances (MBAS) was extracted with 1, 2-dichloroethane using methylene blue colorimetry. Before MBAS was extracted with 1, 2-dichloroethane, some interfering substances were removed by pre-extraction with carbon tetrachloride. LAS in 1, 2-dichloroethane extract was determined by HPLC. LAS in river waters was determined in the similar way. Stationary phase of Shimadzugel PSG-100 and Shimadzu PCH-05 were compared, and it was found that PCH-05 has the following advantages over PSG-100: (i) In river waters and sediments the peaks of LAS were well separated from those of MBAS other than LAS. (ii) Homologous series of LAS with C10C14 alkyl groups were resolved according to the alkyl chain length. (iii) The positionary isomers of phenyl group of LAS were not separated. The method employing PCH-05 was applied to the determination and distribution of homologous series of LAS in river waters and sediment. Recommended conditions for HPLC were as follows: column, PCH-05 (Shimadzu), 4 mm i.d. × 250 mm; mobile phase, 0.08 % (w/v) disodium hydrogenphosphate in 50% ethanol; flow rate, 0.3 ml/min; column temperature, ambient; detector, UV 225 nm. The calibration curve for sodium dodecylbenzenesulfonate was linear within a range of (0.010.3) μg/5 μl (injection volume). The recoveries of known samples were (9199) %.
