Method development and optimization for the determination of selenium in bean and soil samples using hydride generation electrothermal atomic absorption spectrometry

Abstract

The present investigation is the first part of an initiative to prepare a regional map of the natural abundance of selenium in various areas of Brazil, based on the analysis of bean and soil samples. Continuous-flow hydride generation electrothermal atomic absorption spectrometry (HG-ET AAS) with in situ trapping on an iridium-coated graphite tube has been chosen because of the high sensitivity and relative simplicity. The microwave-assisted acid digestion for bean and soil samples was tested for complete recovery of inorganic and organic selenium compounds (selenomethionine). The reduction of Se(VI) to Se(IV) was optimized in order to guarantee that there is no back-oxidation, which is of importance when digested samples are not analyzed immediately after the reduction step. The limits of detection and quantification of the method were 30 ng L(-1) Se and 101 ng L(-1) Se, respectively, corresponding to about 3 ng g(-1) and 10 ng g(-1), respectively, in the solid samples, considering a typical dilution factor of 100 for the digestion process. The results obtained for two certified food reference materials (CRM), soybean and rice, and for a soil and sediment CRM confirmed the validity of the investigated method. The selenium content found in a number of selected bean samples varied between 5.5±0.4 ng g(-1) and 1726±55 ng g(-1), and that in soil samples varied between 113±6.5 ng g(-1) and 1692±21 ng g(-1).

Selenium status in preschool children receiving a Brazil nut–enriched diet

“…Throughout Brazil, the Se levels in soils, as well as the Se content of regional diets, are vastly different [12,30], and the development of region-specific food composition tables is difficult. Therefore, the duplicate-portion method analysis used in this study was important to assess Se intake accurately.…”

Natural variation of selenium in Brazil nuts and soils from the Amazon region

“…Selenium concentration in Brazil nuts can vary by about three orders of magnitude (0.2e512.0 mg kg À1 ) across several regions of South America (Chang et al, 1995;Secor and Lisk, 1989;Pacheco and Scussel, 2007;Parekh et al, 2008) and it has been speculated that this variation is mainly associated with differences in Se concentration in the soil (Reilly, 1999;Secor and Lisk, 1989). However, little is known about selenium concentration in these soils, with only a few studies in agricultural soils from the Amazon region reporting Se concentrations ranging from 419 mg kg À1 (in the state of Par a) to 604 mg kg À1 (in the state of Amazonas) (Shaltout et al, 2011) and in the tributaries of the Orinoco river, Venezuela, ranging from 60 to 5163 mg kg À1 (Yee et al, 1987). In addition, no systematic assessment of the relationship between Se concentration in Brazil nuts and in the soil has yet been reported.…”

Inadequação do consumo alimentar de nutrientes antioxidantes em nefropatas crônicos em hemodiálise

“…No entanto, estudos de consumo alimentar referente ao selênio têm seu valor limitado considerando que este mineral tem diferente distribuição geoquímica. 15 Assim as desse mineral, bem como não elucidam quais os solos produtores de consumo no Brasil, por exemplo.…”