Chemical generation of volatile species of copper - Optimization, efficiency and investigation of volatile species nature

Jakub Šoukal; Oldřich Benada; Tomáš Matoušek; Jiří Dědina; Stanislav Musil

doi:10.1016/j.aca.2017.05.007

Chemical generation of volatile species of copper - Optimization, efficiency and investigation of volatile species nature

Anal Chim Acta. 2017 Jul 18:977:10-19. doi: 10.1016/j.aca.2017.05.007. Epub 2017 May 13.

Authors

Jakub Šoukal¹, Oldřich Benada², Tomáš Matoušek³, Jiří Dědina³, Stanislav Musil⁴

Affiliations

¹ Institute of Analytical Chemistry of the CAS, v. v. i., Veveří 97, 602 00 Brno, Czech Republic; Charles University in Prague, Faculty of Science, Department of Analytical Chemistry, Albertov 8, 128 43 Prague, Czech Republic.
² Institute of Microbiology of the CAS, v. v. i., Vídeňská 1083, 142 20 Prague 4, Czech Republic.
³ Institute of Analytical Chemistry of the CAS, v. v. i., Veveří 97, 602 00 Brno, Czech Republic.
⁴ Institute of Analytical Chemistry of the CAS, v. v. i., Veveří 97, 602 00 Brno, Czech Republic. Electronic address: stanomusil@biomed.cas.cz.

PMID: 28577593
DOI: 10.1016/j.aca.2017.05.007

Abstract

This work is a comprehensive study on chemical generation of volatile species (VSG) of copper for analytical atomic spectrometry. VSG was carried out in a flow injection mode in a special arrangement of the generator. Atomization in a diffusion flame atomizer (DF) with atomic absorption spectrometry detection was mostly used for VSG optimization. Inductively coupled plasma mass spectrometry (ICP-MS) was utilized to investigate generation efficiencies and feasibility of VSG system for ultratrace analysis. Concentration of individual reagents, namely of nitric acid, sodium tetrahydroborate and various reaction modifiers, was optimized with respect to generation efficiency. Triton X-100 and Antifoam B were chosen as the best combination of the modifiers owing to sixfold increase in sensitivity, decrease of tailing of measured signals and long-term repeatability. The addition of 500 μg L^-1 of Ag was found crucial to maintain identical generation efficiency at low concentrations of Cu. This phenomenon was ascribed to the change in the size of generated species. The release and generation efficiency were accurately determined as 56-58 and 31-32%, respectively. The contribution of co-generated aerosol to release and generation efficiency measured by means of Cs and Ba was found negligible, only 0.40 and 0.13%, respectively, which underlines highly efficient VSG of Cu. The nature of volatile species was investigated by various approaches. The results cannot provide the decisive evidence. However, experiments with the DF, ICP-MS and transmission electron microscopy (TEM) indicate that the generated species are not volatile in the true sense but that they are strongly associated with fine aerosol co-generated during VSG. Cu clusters or nanoparticles of very small size (< 10 nm) are presumed but the formation of metastable copper hydride cannot be conclusively excluded.

Keywords: Atomic absorption spectrometry; Copper; Generation of volatile species; Inductively coupled plasma mass spectrometry; Transmission electron microscopy.