Determination of small amount of copper and silver in tin ingot by pobirized Zeeman atomic absorption spectrometry with direct atomization of solid sample in a grapMte-cup cuvette

Abstract

Copper 10 ppm) and silver {0.0 x~x ppm) in a small amount of tin were determined. A small sample {(0.l~l) mg} was prepared through cutting of tin ingot with a pair of nippers. A particle of the sample was atomized with an electrothermal graphite-cup cuvette in argon atmosphere (3 dm3/min). Analytical condition for copper was at 2800 °C for 45 s and for silver at 2500 °C for 45 s. Under these conditions, tin samples of up to 0.4mg for copper and of up to 1 mg for silver were atomized, and the area of absorption signal was measured. As the atomization temperature was high, an aerosol of matrix tin was evaporated. The background absorption (O.Ol'O.l in absorbance) of the aerosol was automatically corrected by polarized Zeeman atomic absorption spectrometer. Calibration curve for copper was constructed with standard solution of copper and for silver with the standard solution of silver together with high purity tin, in which silver content was less than detection limit. The relative standard deviations for copper and silver were (6~28)%. The detection limits (correspond to twice of the standard deviation of noise) were 0.082 ng of copper and 0.011 ng of silver. Those values correspond to copper content of 0.2 ppm (in sample 0.4 mg) and silver content of 0.01 ppm (in sample Img). One graphite cuvette could be repeatedly employed for atomization procedures of (120~200) times. Chemical treatments (dissolution, concentration etc.) for samples were not carried out, so the analytical period of one sample was around 5min. © 1983, The Japan Society for Analytical Chemistry. All rights reserved.