Effect of contamination by oxygen at trace level in miniature flame hydride atomizers

Abstract

A new type of atomization interference, caused by traces of oxygen in gases supplied to the atomizer, has been identified in three different types of miniature flame hydride atomizer for atomic fluorescence spectrometry, namely argon–hydrogen diffusion flame (MDF), flame-in-gas shield (FIGS) and double flame (DF), which is a combination of MDF and FIGS. The interference magnitude is dramatically dependent on the analyte element (Se ≪ As ≤ Sb), on the type of atomizer and on the atomizer operating parameters. The thresholds of interference could be as low as a few parts per million (μl l⁻¹) of oxygen in the carrier gas. The main sources of interfering oxygen are, in order, the oxygen stripped out from sample and reagent solutions in the hydride generation step followed by the oxygen diffusing inside the gas circuit of hydride generation apparatus.