Modified method for the analysis of anionic surfactants as Methylene Blue active substances

Abstract

Determination of anionic surfactants as Methylene Blue active substances (MBAS) in water, waste water and sludge samples is of increasing importance because of the rapidly growing use of different types of anionic surfactants in household and industrial applications. We have developed a modified method for MBAS measurement, using sodium dodecyl sulfate (SDS), an alkyl sulfate anionic surfactant compound, as the reference anionic surfactant compound for the MBAS analysis. The modified method has achieved a reduction in sample size, elimination of the use of expensive glassware, and a decrease in the quantity of chloroform used compared with the standard method. The theoretical relationship between the modified method and the standard method was confirmed by the experimental calibration curves. The linear calibration curves had r² values between 0.994 and 0.999. On the basis of the statistical analysis on the MBAS recoveries from standard addition and spiked samples, the modified method is equally capable of extracting anionic surfactant compounds from the samples, when compared with the standard method.