Pulsed glow discharge in thin-walled metallic hollow cathode. Analytical possibilities in atomic and mass spectrometry

Abstract

In this article investigation of atomization and ionization processes in pulsed glow discharge with atomic absorption and mass spectrometry is reported. It was shown that sample sputtering and atomization in a thin-walled metallic hollow cathode (TMHC) is highly efficient in pulsed glow discharge plasma. Using a TMHC as an atomizer with a Zeeman AAS system a background absorption influence for samples with high matrix concentration was significantly reduced compared with graphite furnace AAS. This effect is attributed to the high efficiency of dissociation of matrix components in pulsed glow discharge. TMHC was also used as an ion source for an analytical system with time-of-flight mass-spectrometry (TOF-MS). Ionization processes in pulsed glow discharge were theoretically simulated using modified algorithms and the results of the simulation were experimentally confirmed. It was shown that Penning ionization significantly contributes to ionization yield even after pulsed discharge termination. Sample sputtering dynamics for different discharge regimes were explained and transportation processes from TMHC to TOF-MS were optimized. Limits of detection for Cd and Cu were 20 and 15 ng l⁻¹, respectively.