DisplayTitle

Rapid Trichloroacetic Acid Extraction and Liquid Chromatography Method for Determination of Nicotinamide in Commercial Cereals

¹Food Composition Laboratory, Beltsville Human Nutrition Research Center (BHNRC), United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Building 161, Beltsville, MD 20705-2350. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Phone: 301-504-8927. Fax: 301-504-8314. E-mail: Wolfw@ba.ars.usda.gov ³Student intern, Eleanor Roosevelt High School, Greenbelt, MD. Current Address: University of Wisconsin, Madison, WI.

Determination of niacin in fortified infant and dairy products has been accomplished using a variety of analytical liquid chromatography (LC) methods. Applications of these LC techniques to other food matrices suffer due to the presence of endogenous absorbing peaks at 260 nm that co-chromatograph with the nicotinic acid and nicotinamide vitamers. We have successfully adapted the LC method of Woollard and Indyk for the determination of nicotinamide in reference and commercial cereal products. Unbound nicotinamide in fortified cereal was extracted with 0.6M tri-chloroacetic acid and chromatographed on a C₁₈ reversed-phase column using a mobile phase of 75% methanol and water (pH 2.8, with formic acid) with sodium dioctylsulphosuccinate (0.1%) as the ion-pairing agent. Using Spectral Analysis ChromQuest software, a three-dimensional view showed only nicotinamide under the LC peak. Similarity index spectral matches of nicotinamide standard and the LC peak were ≈100%, indicating the absence of interferences. Nicotinamide recoveries for the reference cereals of VMA195 and VMA 399 (from AACC International, St. Paul, MN) and GM 19B (from General Mills, Medallion Laboratories, Minneapolis, MN) were 90–103% of assigned value. Experimental values for oat, corn, rice, and bran cereals showed that actual niacin content in commercial cereals may be significantly above (111–170%) declared label values. Because manufacturers may fortify at a level higher than the declared label level to ensure shelf life compliance, these data do have significant implications when making precise estimates of niacin intake based on label claims.