Determination of gallium in soil by slurry-sampling graphite-furnace atomic-absorption spectrometry

A graphite-furnace atomic-absorption spectrometric method, utilizing ultrasonic slurry-sampling has been developed for the determination of Ga in soils. Calibration with aqueous standards and with slurries prepared from a certified soil reference material were both employed. When calibration with soil slurries was used no modifier was needed. Because lower and more variable sensitivity was obtained for Ga in aqueous standards than for Ga in slurry soil samples, external calibration with aqueous Ga standards required a suitable chemical modifier to level out the sensitivity difference. Of the many potential modifiers tested, i.e. Al, As, Co, Mg, Mo, Ni, Pd, Pd+Mg, Se, and Te, Ni was found to be best. When Ni (1.0 mg mL(-1), 10 micro L) was injected to the graphite tube with the aqueous standards or slurry samples (10 micro L) accurate results were obtained. Both methods of calibration gave acceptable accuracy and precision. The repeatability was