Abstract
Determimtion of a trace (010 ppm) of nonionic and ionic surfactants in water has been studied. The method is based on the difference of adsorption ability between polyoxyethylene nonionic (POENPE) and alkylbenzene sulfonate anionic (LAS) surfactants. It was found that POENPE was effectively adsorbed on XAD-2 resin, but LAS was slightly adsorbed. The difference of adsorption ability of XAD-2 for these surfactants seems to be due to the non-polar character of surface of the resin. In order to separate POENPE from LAS, 100 ml of water sample was shaken with 0.2 g of XAD-2. POENPE adsorbed on resin was readily eluted with methanol. After the eluate was evaporated, the residue was dissolved in water, and then POENPE was determined by the cobalt-thiocyanate method spectrophotometrically. LAS in the filtrate was determined by the Methylene Blue method spectrophotometrically. The surfactants in the standard water sample were determined, and the recoveries of POENPE, LAS and Lauryl sulfate in the standard water sample were about 90 %. This proposed method can be applied for routine analysis of surfactants in water. For the complete separation of surfactants, however, it seems to be necessary to search a more suitable adsorbent.
