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ARS Home » Northeast Area » Beltsville, Maryland (BHNRC) » Beltsville Human Nutrition Research Center » Food Composition and Methods Development Laboratory » Research » Publications at this Location » Publication #169231
Title: DETERMINATION OF SELENOMETHIONINE IN YEAST USING CNBR DERIVATIZATION AND SPECIES SPECIFIC ISOTOPE DILUTION GC ICP-MS AND GC-MS

Author
item YANG, LU - INMS, ONTARIO, CANADA
item STURGEON, RALPH - INMS, ONTARIO, CANADA
item MESTER, ZOLTAN - INMS, ONTARIO, CANADA
item Wolf, Wayne
item Goldschmidt, Robert

Submitted to: Journal of Analytical Atomic Spectrometry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2004
Publication Date: 5/30/2004
Citation: Yang, L., Sturgeon, R.E., Mester, Z., Wolf, W.R., Goldschmidt, R.J. 2004. Determination of selenomethionine in yeast using CNBR derivatization and species specific isotope dilution GC ICP-MS and GC-MS. Journal of Analytical Atomic Spectrometry. 19:1448-1453.

Interpretive Summary: A comparison of several methods for quantization of Selenomethionine (SeMet) in yeast was undertaken using species specific isotope dilution with a 74Se enriched SeMet spike in combination with GC ICP-MS. An in-house method was based on digestion of samples by refluxing for 16 hours with 4 M methanesulfonic acid (MSA), derivatization of SeMet with cyanogen bromide (CNBr) and its extraction into chloroform for determination by GC ICP-MS. Based on 78Se/74Se ratio, concentration of 3434 ± 19 µg g-1 (n=6) with a RSD of 0.55 % was obtained. These results are in agreement with a value of 3417 ± 27 µg g-1(n=6) obtained using ID GC-MS detection based on the 106/100 ion ratio. The SeMet accounts for 67 % of the total Se. Based on a 0.25 g subsample, method detection limit was 0.9 µg g-1 . Similar SeMet concentrations of 3415 ± 200 (n=6) and precision of 5.8 % were obtained in yeast following digestion with 4 M MSA and derivatization with methyl chloroformate. These data will be used for government and private sector laboratories analyzing foods and dietary supplements for SeMet.

Technical Abstract: A comparison of several methods for quantization of Selenomethionine (SeMet) in yeast was undertaken using species specific isotope dilution with a 74Se enriched SeMet spike in combination with GC ICP-MS. An in-house method was based on digestion of samples by refluxing for 16 hours with 4 M methanesulfonic acid (MSA), derivatization of SeMet with cyanogen bromide (CNBr) and its extraction into chloroform for determination by GC ICP-MS. Concentrations of 3434 ± 19 (n=6) with relative standard deviation of 0.55 % for SeMet were obtained in yeast based on 78Se/74Se ratio. These results are in agreement with data [3417 ± 27 µg g-1(n=6)] obtained using ID GC-MS detection based on the 106/100 ion ratio. The SeMet accounts for 67 % of the total Se, with a method detection limit of 0.9 µg g-1 for SeMet based on a 0.25 g subsample. Similar SeMet concentrations of 3415 ± 200 (n=6) and precision of 5.8 % were obtained in yeast using 78Se/74Se, following digestion with 4 M MSA and derivatization with methyl chloroformate.