Matrix Modifiers for Feedstuff Selenium Analysis by Graphite Furnace Atomic Absorption Spectroscopy

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Abstract
Gallium, Co, Mn, Ni, Cd, Cu, and Zn, dissolved in methanol, were evaluated for efficacy as an alternative volume matrix modifier in Se analysis of forages and concentrates. Gallium, Co, Mn, and Zn were unsuitable as modifiers. Nickel, Cd, Cu, and modifier "M" (Ni + CD + Cu) were used to test recovery of Se addition (.025, 050, .100, .200, and .500 .mu.g) in meat and bone meal, pelleted grain dust, dry milk replacer, whole soybeans, and alfalfa hay. Recovery of Se with Cu, Cd, and "M" had large and variable SD of means within Se concentrations across feedstuffs and within feedstuff across Se concentrations. Mean percent recoveries of Se with the Ni modifier for the five concentrations over all feedstuffs were 106.4, 102.4, 100.2, 97.5, and 97.4, respectively. Repeated analyses of these same five feedstuffs, plus National Bureau of Standards citrus leaves and corn stalk (recommended Se = .016 .mu.g/g), gave Se concentrations (means .mu.g/g) of .423, .104, .168, .196, .624, .027, and .015, respectively. Results obtained with Cd, Cu, and "M" had larger SD than did results obtained with Ni. Nickel nitrate in methanol as an alternative volume matrix modifier for Se provided reliable and sensitive Se analyses for a variety of feedstuffs.