Determination of trace gallium by electrothermal atomic absorption spectrometry after preconcentration on a membrane filter with a finely pulverized anion-exchange resin

A sensitive method based on preconcentration on a membrane filter with a finely pulverized anion-exchange resin has been developed for the determination of gallium in water samples by electrothermal atomic absorption spectrometry. Gallium (10 - 60) ng, in 20 - 500 mi of a sample solution, was retained as a Pyrocatechol Violet complex anion on a resin at pH 5; the resulting resin was filtered through a membrane filter. A portion of the resin with the membrane filter (3 mm in diameter) was inserted into a cuvette, and the absorbance of gallium was measured at 294.4 nm. The relative standard deviations for five measurements at 30 ng of gallium was 5%. The detection limit was 1.5 ng of gallium in 500 mi (3 ngGal(-1)) of the water sample. The interference of various ions was studied, and the optimum conditions were developed for the determination of gallium in mine-drainage and river-water samples.