Pre-concentration by coprecipitation. Part 1. Rapid method for the determination of ultra-trace amounts of germanium in natural waters by hydride generation–atomic emission spectrometry

Abstract

A rapid method for the determination of ultra-trace amounts of germanium in sea-water, surface water and ground-water has been developed. This method initially involved coprecipitation of gallium and magnesium with hydroxide ions. Subsequent investigations have shown that gallium is unnecessary for quantitative recovery if calcium and carbonate ions are added with the magnesium and the precipitation is carried out at a high pH. The formation of a rather coarse precipitate aids in the filtration step, by reducing the filtration time from hours to minutes without any loss of analyte. The control of pH is crucial to the successful use of this method. Concentrations of germanium in waters have been determined by hydride generation atomic emission spectrometry, with a detection limit for the method of 0.6 pg ml^–1(3σ) for a 1 l sample. Determinations of germanium concentrations in ground, sea and surface waters range from 0.5 to 17 pg ml^–1(3 l sample). Initial experiments into the application of the method to samples spiked with 20 ng ml^–1 concentrations of copper, colbalt, nickel and zinc have proved to be effective.