A ROD-FLAME SYSTEM IN DIRECT LASER ENHANCED IONIZATION ANALYSIS OF HIGH-PURITY SUBSTANCES

Laser enhanced ionization in conjunction with electrothermal microsample evaporation from a heated graphite rod into the flame has been used for the direct analysis of high-purity germanium and CdHgTe alloys. Methods for determining microquantities of copper in germanium and indium in these alloys have been developed. Samples in the form of both solutions and powders of 1-20 mg in weight are used. The interferences of the sample matrix in the two cases are shown to be small and consist of additive ionization background. The detection limit for indium in the CdHgTe solutions is as low as 10(-4)mu-g/g and with the solid samples it can be reduced to 10(-6)mu-g/g. For determinations of copper in germanium, the detection limit is higher since it is limited by the rod material purity. The germanium and CdHgTe samples are analysed using the standard addition and calibration curve methods. A good correlation of the results obtained for the solutions and powders through calibration with aqueous standard solutions indicates that the approach proposed in this work ensures direct analysis of the solid and liquid samples with a high accuracy.