Determination of S-Methyl-, S-Propyl-, and S-Propenyl-L-Cysteine Sulfoxides by Gas Chromatography-Mass Spectrometry after tert-Butyldimethylsilylatio
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- 作者：Kouichiro Tsuge ; Mieko Kataoka ; and Yasuo Seto
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2002
- 出版时间：July 31, 2002
- 年：2002
- 卷：50
- 期：16
- 页码：4445 - 4451
- 全文大小：110K
- 年卷期：v.50,no.16(July 31, 2002)
- ISSN：1520-5118
文摘
A gas chromatographic-mass spectrometric method for the determination of S-methyl-L-cysteinesulfoxide (1), S-propyl-L-cysteine sulfoxide (2), and S-propenyl-L-cysteine sulfoxide (3), specific markercompounds in the genus Allium, is described. The target amino acids were converted to the tert-butyldimethylsilyl derivatives. The products were silylated on the amino and carboxyl groups and onan additional oxygen atom and were separated on a nonpolar capillary column. That incorporation ofthree tert-butyldimethylsilyl groups had occurred was verified by mass spectrometry, which gave anm/z 302 fragment as base peak (amino acid side chain eliminated ion) and m/z 436 (1), 464 (2), or462 (3) as major peaks (tert-butyl function eliminated ion), by electron impact ionization. The detectionlimits for 1 and 2 under selected ion monitoring at m/z 436 (1) and m/z 464 (2), respectively, weredetermined to be 0.3 and 1.8 ng per injection. To clean up the analytes from the solvent extract ofonion, as a representative food material, onion, the sample solution was subjected to combined solidphase extraction. The eluate from a Sep-Pak C18 cartridge was applied to a Bond Elut SCX cartridge(H+ form), followed by washing with 0.1 M hydrochloric acid and elution with 0.5 M ammonia. Froma simulated matrix solution containing 5% sucrose, 1 and 2 were extracted quantitatively, and thedetection yield was ~75%. The contents of 1, 2, and 3 in commercial onion were estimated to be0.3, 3.1, and 3.0 mg, respectively, per gram of fresh weight.Keywords: S-Alk(en)yl-L-cysteine sulfoxide; onion; GC-MS; solid phase extraction; tert-butyldimethylsilylation