TENSAMMETRIC STUDIES OF THE SEPARATION OF SURFACTANTS .1. INVESTIGATION OF SOURCES OF ERROR IN PRECIPITATION OF NONIONIC SURFACTANTS WITH MODIFIED DRAGENDORFF REAGENT

Precipitation of surfactants with modified Dragendorff reagent, being a part of the bismuth active substance (BiAS) standard procedure, was investigated with the use of adsorptive stripping tensammetry and an i ndirect tensammetric method. Triton X-100 was used as a representative surfactant. The washing step with glacial acetic acid, part of the in vestigated procedure, was found to be a serious source of loss of prec ipitate and therefore the main source of error of determination in the BiAS procedure. The concentration of surfactant in the filtrate and a dsorptive losses on the filter were also determined.