Determination of zinc in silicatl rocks by graphite furnace AAS with direct introduction of suspension.

Abstract

A simple method was investigated for the direct determination of zinc in silicate rocks using graphite furnace AAS. The method is based on atomization of zinc with introducing the powdered rock samples suspended in 10% glycerin solution into a furnace. The sample (smaller than 10 μm in size) of 0.55.0 mg containing less than 0.20 μg zinc was placed in a stoppered polystyrene test tube (50 ml). Adding 25 ml of 10% glycerin solution, the sample was uniformly dispersed into the suspension by an ultrasonic agitator for 1 min. Then, 10 μl portion of the suspension was injected into the graphite furnace. The injected sample was dried at 200°C for 20 s, heated at 800°C for 60 s, and atomized at 1600°C for 5 s in an argon atmosphere (argon flow rate; 2 1/min). The background was corrected with the non-absorption line at 213.5 nm, and the peak areas of the zinc signal at 213.8 nm were obtained. The relative standard deviation was 6.3% for 7 times determinations on 43 ppm zinc in a standard silicate rock sample ( JG-1).