Determination of germanium species by hydride generation atomic absorption spectrometry: searching for efficient atomizer
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| Year of publication | 2024 |
| Type | Conference abstract |
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| Description | Concentration trends of Ge species in the environment are now in focus as the industrial consumption of Ge as a technology critical element is increasing. This study included three types of hydride atomizers: diffusion flame (DF), multiple microflame quartz tube atomizer (MMQTA), and dielectric barrier discharge (DBD) for Ge species detection by atomic absorption spectrometry (AAS) after hydride generation (HG). The atomization conditions of three volatile Ge species, which encompass germane (GeH4), monomethyl germanium hydride (CH3GeH3) and dimethyl germanium hydride ((CH3)2GeH2), were thoroughly optimized. Comparable sensitivity was observed among Ge species within each atomizer type. However, sensitivity values were extremely low for Ge, when compared with those reached by HG-AAS for other hydride forming elements. As generation efficiency of Ge species was found quantitative by means of ICP-MS, low sensitivity in HG-AAS is caused either by low atomization efficiency or by the rapid decay of free Ge atoms. The atomization processes and the fate of free Ge atoms were studied by several advanced spectrometric techniques including laser induced fluorescence (LIF), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) employing GeH4 as a model species. Spatial distribution of free Ge atoms can be visualized and their absolute concentration quantified by LIF. Free atoms were found only in the central part of the DBD discharge by LIF at a concentration 20 times lower than expected theoretically. The analyte deposited by decay reactions of free atoms at inner surface of the DF atomizer was characterized by SEM and EDS, implying that Ge is deposited as particles containing elemental Ge rather than Ge oxide. The deposited fraction was also quantified by leaching experiments with ICP-MS detection being around 80% in DBD and MMQTA and below 10% in DF. The results indicate fast decay of free Ge atoms. Another type of hydride atomizer based on a plasma sustained between two tip-shaped rod electrodes in a quartz tube without a dielectric barrier was optimized for atomization of Ge species. The potential of HG-AAS to determine Ge species and mechanism of their atomization in flame and plasma atomizers will be discussed. |
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