[Determination and identification of anions and cations in cosmetics]

A method was developed for the determination of anions and cations (Na+, NH4+, K+, Mg2+, Ca2+,Cl-, Br-, NO2- , NO3- and SO4(2-)) in cosmetics by using ion chromatography with conductometric detection. The eluent for determining anions was 1,2,4,5-benzenetetracarboxylic acid (2.0 mmol/L) with 1.0 mL/min flow rate on anion exchange column (ICS-C25), while that for cations was o-phthalic acid (2.5 mmol/L) and trihydroxyaminomethane (2.4 mmol/L ) with 0.6 mL/min flow rate on cation exchange column (Shim-pack IC-Al). The ions had good linear relations in wide range, and the recoveries were from 93% to 102%.