Research J. Pharm. and Tech. 12(12): December 2019 6149 ISSN 0974-3618 (Print) www.rjptonline.org 0974-360X (Online) REVIEW ARTICLE Methods of Spectroscopy for Selenium Determination: A Review Wissam Zam 1 , Mohamad Alshahneh 2 , Azez Hasan 2 1 Department of Analytical and Food Chemistry, Faculty of Pharmacy, Al-Andalus University for Medical Sciences, Tartous, Syrian Arab Republic. 2 Department of Analytical Chemistry, Faculty of Science, Tishreen University, Syrian Arab Republic. *Corresponding Author E-mail: ws.sarah2005@gmail.com, w.zam@au.edu.sy ABSTRACT: Selenium (Se) is cumulative nonmetallic element that occurs naturally in a range of oxidation states as volatile species or analogues of organic sulphur compounds. At low concentrations, selenium is an essential element; however at higher concentrations it possesses toxicological properties. Its determination requires a sampling procedure to be followed, an initial digestion stage of the sample matrix and the reduction of Se (VI) to Se (IV). Spectroscopic methods for the determination of Se including hydride generation atomic fluorescence spectrometry, hydride generation, graphite furnace, flame atomic absorption spectrometry and spectrophotometric methods are described detailing detection limits and sensitivity. KEYWORDS: Selenium; spectroscopic methods; review; detection limits; sensitivity. INTRODUCTION: Selenium is a cumulative nonmetallic element found in high concentrations in food and water. It has received high attention of researchers because of its dual role as an essential trace nutrient and a toxic element [1,2] . This dual effect has been recognized for many naturally occurring chemicals [1] . Selenium speciation has been attracting much attention in recent years because selenium compounds have been reported to have anticarcinogenic activity and prevent heavy metal toxic effects [3-5] . Selenium is extensively used not only in medicine but also in other fields such as material sciences and in the agronomical area [6] . Since that time many papers appeared devoted to determination of selenium in the environment and biological material. The most common spectroscopic methods used for determination of various species of selenium were hydride generation atomic fluorescence spectrometry [7,8] , hydride generation [9,10] , graphite furnace [11-13] and flame atomic absorption spectrometry [14,15] . In spite of some of the above methods, spectrophotometric methods are popular because of their simplicity and are based on complex formation between the reagents and selenium. In view of the profound recent interest in selenium and its vital biological importance in human health, reviewing modern spectroscopy methods of determination of this element seemed worthwhile. Received on 22.05.2019 Modified on 28.06.2019 Accepted on 24.07.2019 © RJPT All right reserved Research J. Pharm. and Tech. 2019; 12(12): 6149-6152. DOI: 10.5958/0974-360X.2019.01068.0 Methods of spectroscopy for selenium determination Visible absorption spectroscopy: A wide number of rapid, highly sensitive and selective spectrophotometric methods for the determination selenium (IV) were reported. These methods are based on piazselenol complex formation between the reagents and selenium. Selenium was detected in blood samples based on the oxidation of phenylhydrazine –p sulphonic acid coupled with acetyl acetone in an alkaline medium with a detection limit of 0.07μg/ml [16] . 5,6-diaminouracil hydrochloride reagent was developed and used for the determination of Se (IV). The reagent formed a yellow complex with the aqueous solutions of selenium in acidic medium with a detection limit of 0.05μg/ml [17] . Krishnaiah et al. developed a rapid and sensitive method for the determination of selenium in environmental samples based on either the oxidation of 2,4- dinitrophenyl hydrazine hydrochloride by selenium in HCl medium and coupling with N-(1-naphthyl) ethylenediamine dihydrochloride with a maximum absorption peak at 520nm or the oxidation of 4- aminoresorcinol hydrochloride by selenium in H2SO4 medium and coupling with 4-aminoresorcinol hydrochloride to yield a orange red colored product with a maximum absorption peak at 495nm. The detection limits reported were 0.0165 and 0.0335μg/ml, respectively [18] . A similar detection limit of 0.0124μg/ml resulted from the reaction of selenite ions with hydroxylamine hydrochloride, which in turn diazotizes p-Nitroaniline and then coupled with N-1-naphthyl- ethylenediamine dihydrochloride to form a red colored