Simultaneous determination of four non paraben preservatives (benzyl alcohol, phenoxyethanol, sodium benzoate, and salicylic acid) in shampoos by an isocratic HPLC method

Abstract

Salicylic acid (SA), sodium benzoate (SB), phenoxyethanol (PO), and benzyl alcohol (BA) are “non paraben” preservatives commonly used in cosmetic products like shampoos, and often in combination of at least two compounds to assure their antimicrobial effectiveness at low concentrations. In this study, an HPLC-DAD method was developed and validated for simultaneous determination of SA, SB, PO, and BA in commercial shampoos. The method was carried out using an YMC Triart C18 (250 × 4.6 mm, 5 µm) column with a mixture of methanol and 0.02 M solution of phosphate buffer pH 2.7 (35 : 65, v/v) as mobile phase. The flow rate of mobile phase was maintained at 1.0 mL per minute, the injection volume was 20 µL and the UV detection was done at 208 nm for BA and at 230 nm for SA, SB and PO. The method was fully validated according to requirements on analytical method performance of AOAC International and validation results confirmed its reliability and suitability for intended application. The method was employed to determine the four “non paraben” preservatives in 18 commercial shampoos, finding the actual content of these substances in all samples conformed to their regulatory limits.