Determination of Abundances of Fifty‐Two Elements in Natural Waters by ICP‐MS with Freeze‐Drying Pre‐concentration

Abstract

To precisely determine the abundances of fifty‐two elements found within natural water samples, with mass fractions down to fg g−1 level, we have developed a method which combines freeze‐drying pre‐concentration (FDC) and isotope dilution internal standardisation (ID‐IS). By sublimation of H2O, the sample solution was reduced to < 1/50 of the original volume. To determine element abundance with accuracy better than 10%, we found that for solutions being analysed by mass spectrometry the HNO3 concentration should be > 0.3 mol l−1 to avoid hydrolysis. Matrix‐affected signal suppression was not significant for the solutions with NaCl concentrations lower than 0.2 and 0.1 cg g−1 for quadrupole ICP‐MS and sector field ICP‐MS, respectively. The recovery yields of elements after FDC were 97–105%. The detection limits for the sample solutions prepared by FDC were ≤ 10 pg g−1, except for Na, K and Ca. Blanks prepared using FDC were at pg‐levels, except for eleven elements (Na, Mg, Al, P, Ca, Mn, Fe, Co, Ni, Cu and Zn). The abundances of fifty‐two elements in bottled drinking water were determined from five different geological sources with mass fractions ranging from the fg g−1 to μg g−1 level with high accuracy.