Thiocyanate determination by ion pair chromatography

Department of Analytical and Environmental Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania A simple and rapid ion pair chromatographic method has been developed for the determination of thiocyanate. Separation was carried out on a 25 cm × 4.6 mm Ascentis C18 column (5 μm particle size) with a mobile phase containing 2 mmol/l tetrabutylammonium (TBA)-phosphate (pH 6.5) in 40 (v/v) % acetonitrile at a flow rate of 0.5 ml/min. Detection was performed by direct UV absorption at 210 nm. This study investigated the effect of various experimental factors, such as acetonitrile content, pH, and ion-pairing cation concentration in the mobile phase on the retention behaviour of anions. Under optimized conditions, four anions (Br -, NO3 -, Iand SCN-) were effectively separated within 8 minutes. The calibration curve was linear in the thiocyanate concentration range from 5×10-6 to 5×10-4 mol/l with an excellent correlation coefficient of more than 0.999. The limit of detection was 1.5×10-6 mol/l (signal / noise = 3). The method was applied for determination of thiocyanate ions in human saliva. Saliva sample preparation involved only centrifugation and appropriate dilution.