Determination of Selenium in Nuts by Cathodic Stripping Potentiometry (CSP)

Abstract

The aim of this work was to determine the selenium content in nut samples by cathodic stripping potentiometry. Dry-powdered nuts were digested by HNO(3) and dissolved with concentrated hydrochloric acid. To avoid the interference of natural oxygen, the potentiometric determination of selenium was carried out in an electrolyte solution consisting of 2 M CaCl(2) and 4 M HCl. The analysis was executed applying an electrolysis potential of -150 mV for 60 s and a constant current of -30 microA. Under these conditions, detection limits lower than 1.0 ng g(-)(1) were obtained for selenium analysis in nuts. The relative standard deviation of these measurements (expressed as rsd %) ranged from 0.44 to 0.88% while recoveries ranged from 90.2 to 95.3%. The results obtained with the proposed method were compared with those obtained via hydride vapor generation atomic absorption spectroscopy, a common method for determining selenium. The results of the two methods agreed within 5% for almond, hazelnut, and pistachio samples. The mean concentrations of selenium determined in Sicilian samples of almond, hazelnut, and pistachio were 531 +/- 1, 865 +/- 1, and 893 +/- 4 microg/kg, respectively.

Profiling selected phytochemicals and nutrients in different tissues of the multipurpose tree Moringa oleifera L., grown in Ghana

“…Selenium was determined using a previously described method (Dugo, La Pera, Lo Turco, Mavrogeni, & Alfa, 2003). Selenium data is expressed as mean ± SD percentage (%) of dry matter of tissue.…”

Composição química de nozes e sementes comestíveis e sua relação com a nutrição e saúde

“…Dentre eles, destacam-se o perfil de ácidos graxos, contendo, sobretudo os ácidos oléico (C18:1) e linoléico (C18:2) 2 e a relação ω-6:ω-3 da macadâmia 2 , noz 2 , castanha 9 e da amêndoa de baru 4,10 ; o conteúdo considerável de fitoesteróis, com 100 a 200 mg de β-sitosterol por 100 gramas de óleo 11,12 ; os altos teores de vitamina E e de selênio [13][14][15] e, em alguns casos, de fibra alimentar, especialmente de fibras insolúveis 2,16 . O consumo elevado desses fitoquí-micos está associado com a redução do risco de doenças cardiovasculares e de alguns tipos de cân-cer, como de próstata, esôfago, estômago, cólon e reto 17,18 .…”

“…Estudos constataram teores elevados de selênio em amêndoas 14 , avelãs 14,16 , pistache 14 , e, sobretudo, na castanha-do-pará (Tabela 4) 15 . Em adultos saudáveis, foi observado que a concentração do selênio plasmático aumentou significativamente após o consumo de 45g de castanhas--do-pará por dia 37 , durante duas semanas.…”

Cu, Fe, Mn and Zn distribution in protein fractions of Brazil-nut, cupuassu seed and coconut pulp by solid-liquid extraction and electrothermal atomic absorption spectrometry

“…[5][6][7][8] In the latest years, fruits and nuts from Amazon region have arisen interest among the scientific community due to the high concentrations of some essential elements in their compositions. [9][10][11][12][13][14][15][16][17] Special attention are devoted to Brazil-nut (Bertholletia excelsa), known as "castanha-doPará". This nut is a rich source of nutrients, such as proteins (10-20%, m/m), fat (50-70%, m/m), carbohydrates (10-20%, m/m), vitamins, minerals and dietary fiber.…”

“…The protein standard was prepared dissolving 4.0 mg of ovoalbumin in 2.0 mL of deionized water, submitted to Vortex stirring for 2 min and diluted 10 times with deionized water. The spectrophotometer calibration was performed using analytical reference solutions of 4,6,8,10,12,16 and 20 μg of ovoalbumin in 1.0 mL of Bradford reagent.Water, NaCl, and NaOH extracts of the Brazil-nut samples were diluted 100 times and ethanol extract was diluted 10 times. A volume of 50 μL of these solutions was used for protein determination.…”