Simultaneous quantification of peracetic acid and hydrogen peroxide in different water matrices using HPLC-UV

With low potential to generate harmful by-products, peracetic acid (PAA) has drawn increasing attention as an alternative oxidant for disinfection and advanced oxidation processes in wastewater treatment. Commercial formulations contain significant concentrations of both PAA and H₂O₂ in aqueous solutions and a robust method to distinctively quantify the two respective oxidants simultaneously is needed. This study aimed to improve the accuracy of employing methyl p-tolyl sulfide (MTS) and triphenylphosphine (TPP) as indicators for PAA and H₂O₂, respectively, under various environmental conditions, by the detection of the oxidation products of sulfoxide MTSO and phosphine oxide TPPO using HPLC-UV. To improve the analytical method, the reaction rates of MTS and TPP with PAA and H₂O₂, impact of pH on the detection, and matrix effects of real wastewater effluents and produce wash water were evaluated to minimize the interference of H₂O₂ with PAA determination. The determined rate constants of PAA reaction with MTS (k_PAA/MTS=34.6±0.4M^-1s^-1 in 2/1 H₂O/acetonitrile (ACN) (v/v)) and H₂O₂ reaction with TPP ( [Formula: see text] in 1/1 H₂O/ACN (v/v)) provided the fundamental guidance to optimize the method. Overall, a highly accurate and sensitive method for simultaneous quantification of PAA and H₂O₂ (method quantification limit = 0.8 and 6.0 μM, respectively) is established and will be useful for various environmental samples with PAA and H₂O₂ applications.