SIMPLE SIMULTANEOUS DETERMINATION OF SOLUBLE AND INSOLUBLE TRACE-METAL COMPONENTS IN SEA SALTS BY A COMBINED COPRECIPITATION X-RAY-FLUORESCENCE METHOD

An X-ray fluorescence method using the coprecipitation-preconcentratio n technique has been developed for simple determination of both acid-s oluble and insoluble trace metal components, such as manganese, iron, nickel, copper and zinc in sea salts. A salt sample is dissolved in a nitric acid solution, and the residue is filtered off onto a membrane filter. After the pH is adjusted to 7-8, the filtrate is boiled, follo wed by addition of aluminum carrier, oxine and thionalide solutions. T he solution is re-adjusted to pH 9, and kept at 80 - 85 degrees C for 60 min. The precipitates are filtered off onto another membrane filter . X-Ray fluorescence intensities from two filters loaded with the resi due and precipitates are measured and the concentrations of the elemen ts are determined simultaneously using the calibration curves. Detecti on limits were 0.01 mu g g(-1) for manganese and copper, 0.04 mu g g(- 1) for nickel and zinc, and 0.05 mu g g(-1) for iron, regardless of th e soluble and the insoluble components. The present method was success fully applied to the analysis of sea salt samples.