DETERMINATION OF TRACE-ELEMENTS IN ARIMA SPRING WATER BY ICP-AES AFTER COPRECIPITATION WITH IRON(III) HYDROXIDE

ICP-AES was applied to the determination of trace elements (Al, Co, Cr , Cu, La, Mn, Ni, Ti, V, Y, Zn and Zr) dissolved in Arima spring water after the preconcentration of those elements by coprecipitation with iron(III) hydroxide. Arima spa is located in Hyogo prefecture and has a salinity twice that of sea water. The spa waters also contains a hig h concentration of iron with a wide concentration range of 10 similar to 150 ppm as Fe. Accordingly, for the coprecipitation treatment the h igh amount of iron dissolved in the spring water sample itself were us ed. The analytical procedure proposed is as follows. The dissolved iro n was first oxidized by HNO3 treatment and was diluted to around 30 pp m as Fe. The pH of the solution was adjusted to 8.5 with 6 M sodium hy droxide solution before warming for 45 min at 80 degrees C for aging. The iron precipitate was dissolved with 6 M hydrochloric acid after se paration of the precipitate by centrifuging. Almost all the iron was e xtracted into 4-metyl-2-pentanone to remove the iron interference on t he ICP-AES measurement. Ten milliliters of the remaining solution was used to determine the trace elements by ICP-AES after adding Cd ion as an internal standard element. Each recovery of the trace elements was more than 96% and its relative standard deviation was less than 7%. B ased on the analytical results, the water quality of Arima spring has been divided into three groups specified by the determined trace eleme nts as well as major components; group 1 of Na-Cl-Fe type containing l ittle trace elements, group 2 of Na-Cl-HCO3 type containing a high con centration of Y and La and group 3 of HCO3 type with low salinity show ing a high concentration of Ti, La, Al, Cr, Cu and Ni.