COMPARISON BETWEEN DIRECT-CURRENT AND RADIOFREQUENCY GLOW-DISCHARGE MASS-SPECTROMETRY FOR THE ANALYSIS OF OXIDE-BASED SAMPLES

Glow discharge mass spectrometry (GDMS) using either a direct current (de) or a radiofrequency (rf) discharge has been evaluated. For conduc ting samples, comparable results are obtained, as indicated by the uni formity in relative sensitivity factors (RSFs). For the analysis of ra re earth oxide materials, the RSFs for de GDMS are far less affected b y changes in discharge pressure and sample to exit-orifice distance th an those obtained for rf GDMS. Despite the higher variability of RSFs for rf GDMS, very stable and reproducible plasma conditions are obtain ed when working at a fixed pressure and distance. The latter is indica ted by the internal (within-sample) and external (sample-to-sample) re producibility of less than 5 and 15%, respectively.