Nature of the sample for glow-discharge sampling

Samples to be used in dc discharges must be electrically conducting. Metals, alloys and even semiconductors work quite well in this mode. Non-conducting samples must be mixed with a conducting matrix such as pure copper or silver and pressed into a suitable form. On the other hand, an rf discharge allows non-conducting samples to be handled directly, thereby avoiding the need for matrix modification. 

Radio frequency-powered GD sources have been coupled with various analytical spectrometries for more than two decades [167]. Analyses are not limited to conducting samples in fact, electrical insulators such as glass, ceramics and geological materials — some of the most difficult samples to dissolve for solution methods of elemental analysis — can be readily examined. 

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