Radiofrequency capacitively coupled plasma torch with central tubular electrode and outer ring electrode

In the capacitively coupled plasma torch with tip-ring geometry, a part of the sample remains in the mantle of the plasma, without any interaction wit h its hot core, where the dissipated power is at maximum. The authors desig ned a new Ar RF CCP torch with central tubular electrode and outer ring. Th is new torch uses a single Ar flow, which assures the introduction of the s ample through the tubular electrode into the central channel of the plasma. The argon plasma is generated at 275 W and 27.12 MHz and has a good stabil ity when the inner diameter of the tubular electrode is 3.5 mm. In this pap er the structure of the torch and the optimisation of main working paramete rs are presented, as well as the detection limits for Mg, Li, Na and Ca fro m liquid sample, as compared with those obtained in the torch in tip-ring e lectrode geometry. The improved interaction between the pneumatically nebul ized liquid sample and the plasma and the lower background signal assure li mits of detection for Mg, Ca, Na and Li (6, 9, 4, 5 ng/ml) 1.5-8 times bett er than the tip-ring type RF CCP.