Tuesday, November 14, 2006 - 2:00 PM

Analytical Methods and Biotransformations of Selenium.

Donald Suarez, US Salinity Lab., USDA-ARS, 450 W Big Springs Rd., Riverside, CA 92507-4617

A major component of Dean’s research was development of analytical methods.  Lacking suitable existing methods, Dean developed methods for Se+IV and Se+VI  and As+III and As +V speciation using coupled ion chromatography and hydride generation AAS.  This methodology was first utilized in yet another analytical method, an improved  sequential extraction scheme for Se in soil. The first step extracted soluble Se+IV and Se+VI and ligand exchangeable Se-II without oxidation state change, followed by organic associated Se-II, and a total “insoluble” Se. These analytical methods were combined with published gas chromatographic methods in studies examining soil methylation pathways for selenoamino acids, transformations and volatilization of dimethyldiselenide and dimethydiselenide, mineralization of Se containing amino acids and Se speciation in soils, marine shales and evaporation basin soils in Central CA. Other developed analytical methods include a new method for determination of phenolic acids in plants and soils and a series of new analytical methods for soil saccharides, aminosaccharides, amino acids,  soil auxins and glycuronic acids using HPLC.