The direct and accurate determination of major elements Ca, K, Mg and Na in water by HR-ICPMS

A direct, accurate and precise method is reported for major elements Ca, K, Mg and Na measurements in river and drinking water using a high resolution ICP-MS. Double isotope dilution calibration was used for the determination of Mg whereas the combined standard addition and internal standardization (Sc) was used for Ca, K and Na measurements. The method is validated by analysis fresh water SLRS-5, SLRS-6 and SRM1640a with satisfactory results characterized by high precisions of 0.055% to 0.66% RSD (or 0.29\u20131.8% relative combined uncertainty) for all four analytes, superior to those reported in earlier studies. As noted, use of internal standard Sc has significantly (3\u201333 times) improved measurement precisions for Ca, K and Na compared to standard addition calibration alone. The proposed method was applied for the determination of major elements Ca, K, Mg and Na in a candidate drinking water CRM AQUA-1. Values of 1.908\u2009\ub1\u20090.007\u2009\ub5g\u2009g 121, 8.27\u2009\ub1\u20090.14\u2009\ub5g\u2009g 121, 0.660\u2009\ub1\u20090.010\u2009\ub5g\u2009g 121 and 13.76\u2009\ub1\u20090.05\u2009\ub5g\u2009g 121 (u, k\u2009=\u20091) were obtained for Mg, Ca, K and Na in AQUA-1 drinking water, respectively.Peer reviewed: YesNRC publication: Ye