Generation of tellurium hydride and its atomization in a dielectric barrier discharge for atomic absorption spectrometry
Abstrakt
Atomization of tellurium hydride in a dielectric barrier discharge (DBD) atomizer was investigated for the first time. First, the conditions of hydride generation were optimized with the use of a miniature diffusion flame atomizer and high-resolution continuum source atomic absorption spectrometry.
Generation efficiency of more than 90% was determined from a comparison of the response to solution nebulization with inductively coupled plasma mass spectrometry. Subsequently, atomization of tellurium hydride in a plane-parallel configuration of the DBD atomizer was optimized.
Argon was found as the best carrier gas under a flow rate of 75 mL min(-1) while the peak-to-peak high voltage was 18 kV. A limit of detection of 56 ng L-1 (3 sigma, n = 15) and repeatability (RSD) of 2.8% at 5 mu g L-1 were reached.
The accuracy and applicability of this methodology was verified by analysis of water Standard Reference Material NIST 1643f and two model samples of tap and stream water. Laser-induced fluorescence was employed to investigate a spatial distribution of free Te atoms and to estimate atomization efficiency in the DBD.
Significant fractions of free Te atoms were identified all over the length of the optical tube of the DBD atomizer covered by the electrodes and atomization efficiency of up to 100% was quantified. A feasibility of tellurium hydride in-situ collection in the DBD atomizer was studied and collection efficiency of around 50% was found promising for further studies.