Validation of a Rapid Test Method for the Quantification of Priority Anions inDrinking Water by Ion Chromatography-Suppressed Conductivity Detection

Abstract

A simple, rapid (8 min) ion chromatographic test method, using post-column electrolytic suppression, with conductivity detection, is validated for the quantification of Cl-, NO2 -, NO3 -, SO4 2- in river, dam, potable, waste water and in trade effluent, over the linear range: 1-100 mg/L for chloride, 0.05-5 mg/L for nitrite and nitrate, and 0.5-50 mg/L for sulphate. The ion chromatographic separation was carried out using a Dionex Ion PacTM AS22-fast 4 μm column (4 × 150 mm), with a flow rate of 1.2 mL/min, using Na2CO3/NaHCO3 (4.5 mM/1.4 mM) as eluent. The LOQ was in the range 0.025-0.50 mg/L, with an injection volume of 25 μL. The %RSD for retention time and peak area responses was <1%. Spiked recoveries were 87-107% for all 4 target anions. The method was suitable for routine drinking water quality assessment in line with the national regulations. The method was fully validated for accuracy, precision, recovery, LOQ, bias/trueness, selectivity, Measurement Uncertainty (MU), etc. The method validation data complied with the international requirements for testing laboratories for ISO/IEC 17025 accreditation.