APPLICATION OF AN ALL-SOLID-STATE ION-SELECTIVE ELECTRODE FOR THE AUTOMATED TITRATION OF ANIONIC SURFACTANTS

A poly(vinyl chloride) matrix membrane electrode responsive to anionic surfactants in an all-solid-state graphite-epoxy support was applied to the determination of anionic surfactants by potentiometric titratio n, using Hyamine 1622 as the titrant, in a pH 2.2 phosphate buffer. Th e results from this method compare favourably with those of the two-ph ase mixed indicator titration method for several commercial anionic su rfactants (alkylsulfates, alkylbenzenesulfonates, alpha-alkene sulfona tes, alkyl ether sulfates and sulfosuccinates). The performance charac teristics improve the commercially available surfactant electrodes: th e standard deviation for the titration of 4 mmol dm(-3) dodecylsulfate with 4 mmol dm(-3) titrant is 0.15% (n = 23), the relative standard d eviation of the end-point potential is 0.95% and the average value of the potential jump is 140 mV, which allows for the titration of surfac tants at concentrations down to 10 mu mol dm(-3) and shows its applica bility in routine analysis.