Characterization of Selenium Species in Brazil Nuts by HPLC−ICP-MS and ES-MS

Abstract

Brazil nuts have been classified as the foodstuffs that contain the highest level of unadulterated selenium, an essential trace element that appears to prevent cancer. To date, characterization of the selenium species in brazil nuts has not yet been investigated. In this work, various sample preparation approaches, including microwave extractions and enzymatic treatments, are examined with the goal of species preservation and subsequent selenium speciation; of these approaches, an enzymatic treatment with Proteinase K proved most effective. High-performance liquid chromatography (HPLC) separation strategies and inductively coupled plasma mass spectrometry (ICP-MS) detection schemes will also be presented. Extracts are evaluated against available standards for the commercially obtainable seleno-amino acids, selenomethionine (SeMet), selenoethionine (SeEt), and selenocystine (SeCys); selenomethionine was demonstrated to be the most abundant of these seleno-amino acids. Further characterization of unidentified selenium-containing peaks is attempted by the employment of several procedures, including electrospray-mass spectrometry (ES-MS). A peptide structure was identified; however, this was considered a tentative proposal due to the large background produced by the extremely complicated brazil nut matrix.

Selenium speciation by high-performance anion-exchange chromatography–post-column UV irradiation coupled with atomic fluorescence spectrometry

“…KBH 4 (Tianjin Refined Chemical Institution, China) and KOH (Acros, USA) were of analytical grade. 1.5% (w/v) KBH 4 was prepared in 0.2% (w/v) KOH solution.…”

“…Only one UV cracker supplied by the manufacturer was utilized to realize the transformation of all selenium species. No other reductant except HCl and KBH 4 were added. The simplification of the hyphenation equipment reduced the peak breadth effectively and gave symmetric and sharp chromatographic peaks.…”

“…While HPLC is simpler than GC because it does not imply complicated derivatisation steps to form volatile compounds before injection. The most widely used liquid chromatographic modes are reversed-phase ion-pair [4][5][6] and ion-exchange chromatography [7,8]. Generally, reversed-phase ion-pair chromatography was used for separation of organic selenium, such as selenoamino acids, while ion-exchange chromatography has great advantage for separation of inorganic selenite and selenate.…”

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

“…Caruso and co-workers 18 studied the distribution of various elements of nutritional and toxicological interest in different molecular weight fractions, ranging from 0.18 to 14 kDa. Chemical speciation has been accomplished for As and Se in Brazilnut [20][21][22] and Ni, Cu, Zn and Mn in different edible nuts. 19,23 Cupuassu (Theobroma grandiflorum) has a whiteyellow pulp with pleasant acidic taste and a strong fragrance, which is widely consumed as juice, ice cream and jam.…”

Studying the distribution of Selenium in buffalo and cow's milk whey

“…[6][7][8] In fact, studies have shown that selenium in the form of seleno-amino acids is more easily absorbed by the body than inorganic forms. 9 The scientific community has shown increasing interest in the determination of the elemental composition of milk, because of its important role in human health. 10,11 The concentration of selenium in milk has been reported to vary by geographical region, and depends on factors such as selenium levels in soil and water, as well as in local plants and food.…”