Quantification of anions and cations in environmental water samples - Measurements with capillary electrophoresis and indirect-UV detection

The aim of this study was to validate two separation methods for determinat ion of inorganic anions and cations from natural waters with capillary elec trophoresis (CE) by using indirect-UV detection. The research is related to method development for screening of groundwater samples obtained in site i nvestigations for spent fuel of the Finnish nuclear industry. In CE analysi s, anions were separated in pyromellitic acid (pH 7.7) in the order bromide , chloride, sulphate, nitrite, nitrate, fluoride and dihydrogenphosphate. C ations were separated at pH 3.6 after anions using an 18-crown-6-ether solu tion. In these analyses, ammonium migrated first followed by potassium, cal cium, sodium and magnesium. The concentrations of the ions in the natural w ater samples were calculated by using two or three calibration curves made using reference solutions at concentration levels of 0.5-250 mg/l. The repe atabilities of the anion and cation methods were tested using laboratory-ma de reference sample mixtures with high and low salt concentrations. The lim its of quantification in the analyses were between 0.02 and 0.1 mg/l, depen ding on the ion. Concentrations of ions tested in natural waters varied fro m a few milligrams to tens of grams per litre. (C) 1999 Elsevier Science B. V. All rights reserved.