Chapter 22 Selenium

Abstract

This chapter focuses on the determination of total selenium in clinical materials, especially body fluids such as whole blood, serum, and urine. An overview of various techniques with particular emphasis on those techniques used currently for both routine and research applications is provided. The analytical chemistry of organic and biochemical selenium covering glutathione peroxidase, selenoamino acids, and metabolites such as dimethyl- and dimetyldiselenide, trimethylselenonium and hydrogen selenide is discussed. A broad range of analytical methods are capable of determining selenium in human materials few of them satisfy clinical laboratory requirements of simplicity, reliability and speed. The definitive methods are those that represent the ultimate in quality and are generally so sophisticated that they are not in common usage. Such methods for selenium are Neutron Activation Analyses (NAA) and mass spectrometry that employ isotope-dilution techniques negating the use of an external standard. Reference methods are those that are tested against the definitive methods and/or represent the best method available for use under well controlled routine conditions. The Hydride Generation Atomic Absorption Spectrometry (HG-AAS) is also used. The fluorometric method is a popular technique and is one of the methods of longest standing in the determination of selenium in biological materials.