Development of a Highly Sensitive and Simultaneous Analytical Method for 20 Elements in Raw and Tap Waters Using DRC-ICP/MS and Removal Characteristics of These Elements in the Process of Water Treatment

A simultaneous multi-component analytical method for 20 types of elements in raw and tap-water samples (Cd, Se, Pb, As, Cr, B, Zn, Al, Fe, Cu, Mn, Sb, U, Ni, Ba, Bi, Ag and Mo, as listed in the "Water Works Law", and Li and Sr, which are not-listed but are frequently detected) was studied using DRC-ICP/MS. The investigation revealed 1) that the optimum cell-gas flow rates to control plasma-based interferences was 0.3 mL min−1 for As and 0.6 mL min−1 for the other elements (Cr, Mn, Fe, Ni, Cu, Zn and Se), and 2) that Be, Ga, In and Tl are the most appropriate elements for the internal standards, except in the cases of Co and Y, which are influenced by their concentration level in raw water. Under these analytical conditions, verification by spiked recovery tests exhibited that the recovery rate is 90 – 110%, and that the variation coefficient is below 10%. The levels of the determination limits for each element were ng L−1 – μg L−1, which demonstrates the possibility of measurements for low-concentration samples. From all of these results, this analytical method has been confirmed to be both highly sensitive and accurate. Furthermore, studies of the removal performance for 20 different elements from raw to tap water in an advanced water-purification facility showed that Mn, U, Fe, Bi, Ag and Al can be easily removed (removal ratio of over 80%). On the other hand, Se, Li, Sb, Ba, B, Mo and Sr can hardly be removed (removal ratio of below 20%).