High Selective Determination of Anionic Surfactant Using Its Parallel Catalytic Hydrogen Wave

A faradaic response of anionic surfactants (AS), such as linear alkylbenzene sulfonate (LAS), dodecyl benzene sulfonate and dodecyl sulfate, was observed in weak acidic medium. The faradaic response of AS includes (1) a catalytic hydrogen wave of AS in HAc/NaAc buffer that was attributed to the reduction of proton associated with the sulfo-group of AS, and (2) a parallel catalytic hydrogen wave of AS in the presence of hydrogen peroxide, which was due to the catalysis of the catalytic hydrogen wave of AS by hydroxyl radical OH electrogenerated in the reduction of hydrogen peroxide. The parallel catalytic hydrogen wave is about 50 times as sensitive as the catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave, a high selective method for the determination of AS was developed. In 0.1 mol/L HAc/NaAc (pH = 6.2 ± 0.1)/1.0 ± 10⁻³ mol/L H₂O₂ supporting electrolyte, the second-order derivative peak current of the parallel catalytic hydrogen wave located at-1. 33 V (vs. SCE) was rectilinear to AS concentration in the range or 3.0 × 10–⁶-2.5 × 10–⁴ mol/L, without the interference of other surfactants. The proposed method was evaluated by quantitative analysis of AS in environmental waste water.