GLOW-DISCHARGE OPTICAL-EMISSION SPECTROSCOPY AS APPLIED TO THE ANALYSIS OF POWDERED MATERIALS

The qualification of glow discharge optical emission spectroscopy (GDOES) for the analysis of powdered materials briquetted to pellets after blending with an excess of copper powder is investigated. Two fields of application result: (a) Due to atomic transport processes during GD excitation, influences of the kind of binding and of the surrounding of analyte elements are reduced to such a degree that universal techniques can be elaborated. By the technique described here the true contents are matched in a wide variety of analytical substances to within a factor of about 1.5. The power of detection should then be improved. (b) Matrix-specific calibrations enable quantitative determinations with a RSD of about 12%, if penetration of air into the excitation atmosphere is prevented. Therefore a special device, called "cap", is described; it maintains the excitation atmosphere also at the back of the pellet. For further improvement in the precision, the influence of the grain size below 60-mu-m on the homogeneity of the plasma has still to be investigated.