SCHEDULED MAINTENANCE
Determination of Selenomethionine in Wheat Samples: Comparison of Gas Chromatography-Microwave-induced Plasma Atomic Emission Spectrometry, Gas Chromatography-Flame Photometric Detection and Gas Chromatography–Mass Spectrometry
Abstract
A method is described for the selective determination of
selenomethionine in wheat samples. The method is based on three steps
prior to the determination: (1) hydrolysis of the proteins with
tetramethylammonium hydroxide, (2) clean-up on an aluminium oxide column
(acid form), (3) derivatization to convert selenomethionine into a
compound suitable for GC. The derivatization reaction consists in
esterification of the carboxylic acid group with propan-2-ol in 4 mol
l
-1
HCl medium and subsequent acylation of the amino
group with heptafluorobutyric anhydride. The parameters affecting the
efficiency of both reactions were optimized, as well as the esterification
medium. Other esterification and acylation reagents were also tested.
Three different detection techniques were evaluated using selenomethionine
standard solutions: FPD, MIP-AES and MS. Electrothermal AAS was also
tested, but proved to be unreliable. MS was selected as the best
option.
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