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Solid Phase Extraction/Liquid Chromatography Method for the Determination of Niacin in Commercial Flour Products
Author(s) -
LaCroix Denis E.,
Wolf Wayne R.
Publication year - 2007
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-84-2-0116
Subject(s) - research center , library science , agriculture , engineering , agricultural economics , geography , political science , archaeology , law , computer science , economics
The Food Composition Laboratory has previously reported on successful methods to determine niacin (or nicotinarnide) in a variety of food matrices. Various problems previously encountered in applying these approaches to determination of niacin in enriched commercial flour products have now been overcome. We had previously employed solid phase extraction (SPE) following a standard acid digestion procedure (Methods 944.13, 960.46; AOAC 2000) as a sample clean-up step before analysis of infant formula and processed cereal samples for nicotinic acid by liquid chromatography (LC) (LaCroix et al 2001, 2002a,b). This SPE/LC method was then successfully applied for determination of niacin in wheat flour reference materials but was unsuccessful for commercial all-purpose wheat flour due to the co-elution of excessive endogenous 260-nm absorbing LC peaks occurring for this matrix (LaCroix 1999). Since nicotinamide is the main form of niacin added to formulated or enriched products, Woollard and lndyk (2002) have developed a trichloroacetic acid (TCA) extraction of nicotinamide in milk products before LC analysis, eliminating the acid digestion step. We have investigated the application of Woollard's TCAILC method with modifications for the successful quantitative analysis of processed enriched cereal products for nicotinamide (LaCroix et al 2005) but were unable to utilize this method for enriched commercial wheat flour due to the presence of excessive fine particles that were not removed by 0.25-pm filtration. Therefore, we have reexamined our earlier acid digestion SPE/LC method to determine niacin in the enriched commercial flours as nicotinic acid. As described in earlier reports (LaCroix et al 2002h, 2005), use of a multiwavelength photodiode array detector and analysis of the subsequent spectral scans allows definitive visual information of the presence of one or more compounds under an LC peak, allowing confirmation of the purity of the chromatographic peak.