Abstract
A simple and selective method is proposed for the determination of alkylbenzenesulfonate (LAS) in water by high-performance liquid chromatography (HPLC). LAS was extracted with methyl isobutyl ketone (MIBK) from aqueous media quantitatively in the presence of sodium chloride. LAS in MIBK extract was determined by HPLC without other pre-treatment. A Nippon bunko SIL C-18 was used as a stationary phase (stainless steel column 4.6 mm i.d.×250 mm) and a 80 % ethanol solution was used as an eluent (flow rate, 1 ml/min; column temperature, ambient; detector, UV 225 nm). The peak of LAS was very sharp and separated completely from that of MIBK. Homologous LAS were separated by using a Unicil C-18 column (4.6 mm i.d.×250 mm) as a stationary phase and a mixture of 0.005 M tetrabutylammonium bromide and 0.001 M disodium hydrogenphosphate in 80 % ethanol solution was used as an eluent (flowrate, 1.5 ml/min). The effect of pH and sodium chloride concentration on the determination of LAS were examined. The recommended conditions are as follows:pH, higher than 9 (adjust the pH with sodium hydroxide solution) ; sodium chloride concentration, 1 w/v %; final volume of aqous phas, 100 ml; MIBK, 10 ml. The calibration curve for sodium dodecylbenzenesulfonate was linear within a range of (0.0050.2) p.g/5μl (injection volume of MIBK layer). The coefficient of variation was 2.3 % for 0.025 μg of LAS. The recovery of LAS from river water and sewage water were (90104) % and (8187) %, respectively.
