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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 #78949


item Wolf, Wayne
item Lacroix, Denis

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Modern measurement systems for food components often require use of smaller and smaller sample sizes down to mg sizes for some new micro techniques. This puts a stronger demand on development of reference materials with defined homogeneity for subsampling at these lower levels. One approach to evaluate the homogeneity of materials is characterization of sampling constants, defined as that amount of material that gives a 1% error for subsampling. This approach was developed for geological sampling and has been applied in a limited way for inorganic components in food/biological materials. We have extended this approach to the determination of the sampling constants for an organic component, niacin, in the SRM 1846 Infant Formula material. This material was produced by blending of a dry vitamin mix (5% weight) into the bulk spray dried powder, for long term stability purposes. By analyzing similar aliquots of a reconstituted homogeneous fluid solution of a large sample size, in comparison to smalle portions of dry powder, an estimate of the variation due to sampling can be separated from estimates of variation due to analysis. Using either the AOAC microbiological method or a newly developed HPLC method of analysis, sampling constants for the niacin content of SRM 1846 are in the range of 1-3 grams. Extending this sampling constant approach to organic components in foods will significantly aid food analysts to obtain more reliable data on components required for labeling and research.