Indirect determination of surfactants by adsorptive voltammetry: Part 2: Determination of hexadecyl trimethyl ammonium bromide and cetyl pyridinium chloride in industrial and consumer products

A method is described for the indirect determination of trace and ultratrace concentrations of hexadecyltrimethylammonium bromide (HTMAB) and cetyl pyridinium chloride (CPC) in industrial and consumer products by adsorptive voltammetry The determination of HTMAB at the trace concentration was accomplished by an indirect adsorptive polarography on a dropping mercury electrode (DME), while the determination of ultratrace amounts of CPC was performed by an indirect adsorptive stripping voltammetry on a hanging mercury drop electrode (HMDE). The detection limits accomplished for these surfactants were 5 mg/L and 10 μg/L, respectively. These were up to 100 times lower than those obtained by the spectrophotometric method. The linear concentration ranges accomplished for the surfactants under the specified conditions were 0–65 mg/L and 0–300 μg/L, respectively. The development and the incorporation of a simple and rapid separation scheme based on the use of a C₁₈ sep‐pak cartridge with the adsorptive polarographic and voltammetric techniques were effective in overcoming the matrix interference problem from commercial domestic products. The application of the method to industrial and consumer products, such as disinfectant, lozenges, and mouth wash solutions was successful, resulting in an average recovery efficiency of 93 ± 9% for both surfactants.