Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/2009
Publication Date: 5/15/2009
Citation: Patterson, K.K., Holden, J.M. 2009. USDA’s National Food and Nutrient Analysis Program: analytical quality control procedures for food composition research. International Symposium on Analysis Program for Constructing Database about Nutrient Composition of Foods, May 11-15, 2009, Seoul, Korea.
Technical Abstract: Representative food samples collected under the United States Department of Agriculture's (USDA) National Food and Nutrient Analysis Program (NFNAP) are analyzed for composition of nutrients and other bioactive components. Standard procedures have been developed to describe how these primary food samples are to be homogenized, composited, and stored following their shipment from nationwide locations to the centralized processing laboratory before they are analyzed. Those laboratory procedures ensure that nutrients are not lost from the samples before they can be analyzed. Some of the aliquots of each sample composite are sent to laboratories for analysis while other aliquots are retained as reserves and archives in case additional sample material is needed. Three types of laboratories are used to analyze the samples: commercial, government, and university. Some of these laboratories have expertise for specific nutrients, e.g., carotenoids and vitamin D, while others analyze samples for many nutrients. Laboratories are required to use valid methods and to have demonstrated their ability by analyzing certified reference materials (CRM) and achieving acceptable results. CRM are homogeneous quality control (QC) materials that are commercially available from recognized organizations, e.g., National Institute of Standards and Technology, USA, and have certificates which provide nutrient values and uncertainty ranges for selected nutrients. Every laboratory used has been validated for the specific method used to analyze each nutrient. When the homogenized food samples are sent to the laboratories for analysis, each group of samples includes QC material. These may be either CRM or control composites (CC) developed for NFNAP. Since CRM are expensive and in limited supply, CC have been developed to be used as a secondary QC material. The CC are derived from large homogenous batches of foods that have been produced, packaged, and stored in the same way that the test food samples are stored. Generally the nutrient content of these CC have been established and validated by analysis of the CC and a CRM at the same time. Use of a rigorous analytical quality control program which includes CRM and CC can support the continuous monitoring of accuracy and precision of analysis. The procedures developed for the NFNAP help to ensure that the estimates for the nutrient content of the foods are valid and reliable.