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United States Department of Agriculture

Agricultural Research Service

Title: Determination of Niacin in Food Materials by Isotope Dilution Mass Spectrometry

Authors
item Goldschmidt, Robert
item Wolf, Wayne

Submitted to: Journal of Association of Official Analytical Chemists International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2007
Publication Date: June 1, 2007
Citation: Goldschmidt, R.J., Wolf, W.R. 2007. Determination of niacin in food materials by isotope dilution mass spectrometry. Journal of Association of Official Analytical Chemists International. 90(4):1080-1089.

Interpretive Summary: The availability of deuterium-labeled nicotinic acid makes stable isotope dilution mass spectrometry (SIDMS) coupled with liquid chromatography (LC) an attractive option for the determination of the water-soluble B-vitamin, niacin, in food samples. We present a method based on acid digestion, solid phase extraction (SPE) with a strong cation exchange (SCX) column, and reversed phase chromatography with a C18 column. Ionization is by positive ion electrospray. Although analysis can be accomplished in selected ion recording (SIR) mode, it is subject to interference problems similar to those found with other LC determinations of niacin. The additional selectivity of multiple reaction monitoring (MRM) mode, however, largely eliminates interference problems. The method is applied to both fortified samples and samples with only endogenous niacin, including milk samples with sub-ppm niacin levels. The method is capable of determining niacin levels even to the ppb range. These data will be used by food analysis laboratories in the public and private sector to determine niacin in food materials to meet requirements for food labeling, data bases and research purposes.

Technical Abstract: The availability of deuterium-labeled nicotinic acid makes stable isotope dilution mass spectrometry (SIDMS) coupled with liquid chromatography (LC) an attractive option for the determination of the water-soluble B-vitamin, niacin, in food samples. We present a method based on acid digestion, solid phase extraction (SPE) with a strong cation exchange (SCX) column, and reversed phase chromatography with a C18 column. Ionization is by positive ion electrospray. Although analysis can be accomplished in selected ion recording (SIR) mode, it is subject to interference problems similar to those found with other LC determinations of niacin. The additional selectivity of multiple reaction monitoring (MRM) mode, however, largely eliminates interference problems. The method is applied to both fortified samples and samples with only endogenous niacin, including milk samples with sub-ppm niacin levels. The method is capable of determining niacin levels even to the ppb range.

Last Modified: 7/22/2014
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