The effect of the presence of volatile organoselenium compounds on the determination of inorganic selenium by hydride generation

Abstract

As a result of microbiological activity it is possible to find dimethylselenium (DMSe) and dimethyldiselenium (DMDSe) in a wide type of environmental samples, such as soils, sediments, sewage sludges and plants where methylation can take place. Selenium determination by hydride-generation (HG) techniques requires its presence as Se(IV). Consequently, inorganic speciation by hydride generation techniques is done by first determining Se(IV) and then, after reduction of Se (VI) to Se(IV), the total selenium. Therefore, the concentration of Se (VI) is evaluated as the difference between total inorganic selenium and Se(IV). In the present work it could be demonstrated that DMSe and DMDSe are forming other volatile species by reaction with sodium borohydride, applying the same reduction condition as for inorganic selenium. These species are subsequently detected by several atomic techniques (atomic absorption AAS, atomic fluorescence AFS and inductively coupled plasma-mass spectrometry ICP-MS). The error that their presence can cause in determination of inorganic selenium has been evaluated. The magnitude of this error depends on the specific analytical detector used.The coupling of pervaporation-atomic fluorescence is proposed for the identification of these species and pervaporation-gas chromatography-atomic fluorescence for their individual quantification.

State of the art report of selenium speciation in biological samples

“…The comparison of detection (LOD) limit for inorganic selenium species shows 10 ng, and 1 ng for flame AAS and graphite-furnace AAS. 126 More recently, matrix interferences have been investigated for hydride generation coupled to AAS, AFS, and ICP-MS. 127 Atomic emission detection (AED) based on a previously commercial available microwave induced plasma source was a very cost-effective selenium-specific detector for gas chromatography, but has been replaced more and more by an alternative atmospheric-pressure plasma source, e.g. the inductively coupled plasma (ICP), which is a good choice for HPLC and GC detection in particular in combination with mass spectrometry.…”

Hollow fiber liquid phase microextraction followed by high performance liquid chromatography for determination of ultra-trace levels of Se(IV) after derivatization in urine, plasma and natural water samples

“…However, GF-AAS is very sensitive to matrix interferences [16]. Several reports based on high performance liquid chromatography (HPLC) [17], gas chromatography (GC) [18] and capillary electrophoresis (CE) [19] coupled with ICP-MS for selenium analysis have been published. Indeed, selenium detection using ICP-MS suffers from two main difficulties.…”

Mild sample pretreatment procedures based on photolysis and sonolysis-promoted redox reactions as a new approach for determination of Se(iv), Se(vi) and Se(−II) in model solutions by the hydride generation technique with atomic absorption and fluorescence detection

“…25 Recently, other Se species that could be present in soil, sediment and plants, such as dimethylselenium and dimethyldiselenium, have been shown to contribute to the Se(IV) signal when hydride generation is employed, hence causing interference. 33 The occurrence of these species in the soil sample analyzed here is thought to cause a negligible error on Se(IV) determination, since both concentration in the sample and sensitivity are much lower than that of Se(IV) by FI-HGAAS.…”