A comparison of three methods for the convenient determination of sodium dodecyl sulfate in aqueous solutions

Three methods for determining the concentration of sodium dodecyl sulfate (SDS) in aqueous solutions have been investigated. The first was to titrate SDS by cetyltrimethylammonium bromide (CTAB), where the endpoint (corresponding to 1:1 neutralization) was determined by measuring the potential drop between a surfactant ion selective electrode and a silver/silver chloride reference electrode. The second was to measure the endpoint of an analogous titration by following the formation of the insoluble CTAB/SDS complex with turbidimetry. The third was to measure the turbidity of a solution as a function of SDS concentration in the presence of myristyltrimethylammonium bromide (MTAB). Of these methods, which all provide a reasonable assessment of the SDS concentration, the last was certainly the fastest and most convenient, particularly for large numbers of samples. (C) 1998 Academic Press.