INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH LOW-POWER NITROGEN AND OXYGEN PLASMAS

With a low-power radio-frequency generator (1.8 kW, 27.12 MHz), N2 and O2 plasmas were obtained by slightly modifying the load coil and matc hing circuit. After the Ar plasma was generated, the outer and carrier gases of Ar were gradually replaced by N2 or O2. The replacement of t he intermediate Ar gas by N2, however, was impossible. The detection l imits of inductively coupled mass spectrometry with the N2 and O2 plas mas, in which the outer and carrier gases were 100% N2 and O2, respect ively, were comparable or lower for the elements with ionization poten tials lower than 6.5 eV, but generally higher for the other elements, compared to those obtained with the Ar plasma. Polyatomic ions resulti ng from Ar, such as ArO+ and Ar2+, were considerably attenuated with t he N2 and O2 plasmas, although the intensities of ArN+ and analyte oxi de ions increased with these plasma, respectively.