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United States Department of Agriculture

Agricultural Research Service

Research Project: MEASUREMENT SYSTEMS FOR DETERMINATION OF VITAMINS IN FOODS AND DIETARY SUPPLEMENTS

Location: Food Composition and Methods Development Lab

2009 Annual Report


1a.Objectives (from AD-416)
Objective 1: Evaluate existing measurement systems and determine the need for improved measurements for water and lipid soluble vitamins (e.g., vitamins D and E and selected B vitamins), for which significant public health concern and inadequate composition data exists in foods and dietary supplements. Sub-Objective 1.A: Systematically evaluate public health concerns and adequacy of food composition data for vitamins and matrices to prioritize improved measurement needs, including methods and available Reference Materials. Sub-Objective 1.B. Develop detailed evaluations of measurement systems for priority analytes and matrices. Sub-Objective 1.C. Develop specific purpose statements for development and/or updating of methods for measurements of single or multiple vitamins.

Objective 2: Develop and validate new or updated analytical methods using current technology to determine the levels of water-soluble vitamins (WSV), lipid soluble vitamins (LSV) and/or other components for foods and dietary supplements. Sub-Objective 2.A: Develop/update and optimize measurement procedures to establish validated capability for simultaneous measurements of multiple WSV (SimWSV). Sub-Objective 2.B: Develop and validate analytical methods for the determination and quantification of LSV (A, D, E, and K) and lipids in food matrices and dietary supplements. Sub-Objective 2.C Develop/update and optimize measurement procedures to establish validated capability for measurements of vitamin B12 in dietary supplements and foods. Sub-Objective 2.D Develop multivariate calibration methods for simultaneous determination of multiple vitamins in extracts with no prior chromatographic separations.

Objective 3: Develop and validate sample preparation procedures to optimize extraction, remove interferences, and/or to concentrate difficult to analyze vitamins in foods and dietary supplements.

Objective 4: Catalyze cooperative activities to identify and provide improved measurement systems and essential Reference Materials for vitamins in foods and dietary supplements. Provide analytical data to characterize the vitamin content of selected Reference Materials. Sub-Objective 4.A: Generate information with developed and validated methods to assign value-added information on vitamin content to available Reference Materials. Sub-Objective 4.B: Catalyze development of overall measurement systems for vitamins in foods and dietary supplements.


1b.Approach (from AD-416)
Objective 1: Evidence-based reviews will provide priorities for specific vitamins, define adequacy of existing data, and define quality of data required for future needs. The present state of the performance of individual labs and the adequacy of analysis of specific vitamin measurement systems will be evaluated from extensive data available from the USDA contract analyses conducted as part of NFNAP and DSID. Clearly defined purpose statements will be developed for specific applications. Objective 2: Improved procedures will be developed to simultaneously measure water soluble vitamins (SIMWSV) [thiamin, riboflavin, niacin, pyridoxine, folic acid, pantothenic acid, biotin, choline, and ascorbic acid] in foods and dietary supplements (DS). SIMWSV and LC-IDMS methods for DS will be extended to fortified foods. The additional challenges of natural levels of vitamins in unfortified foods require different approaches or compromise conditions to obtain acceptable analytical results. We will examine newer chromatographic separation modes such as hydrophilic interaction liquid chromatography (HILIC) and aqueous normal phase (ANP) chromatography to improve these separations. A defined protocol of intra-laboratory validation will be carried out following AOAC guidelines. The FCMDLVitamin D method is implemented for analysis of food samples, and additional foods, dietary supplements and reference materials will be analyzed. IDMS methods will be initiated for other lipid soluble vitamins A, E, and K. The FCMDL method to determine the low levels of B12 in vitamin supplements using dual column LC/UV will be extended to fortified foods using sensitive LC/MS techniques and collaboratively cross-validated to the microbiological method. The possibility to calibrate spectral fingerprints (information with no chromatographic separation) of extracts of various types of food and dietary supplement materials to obtain quantitative information about vitamin content will be explored. Calibration models will be developed and validated.

Objective 3: Multiple extractions for WSV with different buffers, pHs, and multiple extraction approaches (including classical and modern methods such as pressurized liquid extraction [PLE], microwave-assisted extraction [MAE], ultrasonic irradiation, stirring, shaking, and Soxhlet) will be systematically explored to ensure complete extraction and compare extraction efficiencies of different procedures. The lipid soluble vitamins (LSV) (A, D, E, K) would be similarily extracted with a organic solvents of different polarities.

Objective 4: FCMDL capability for high quality vitamin determinations will be applied to provide reference measurements to value to NIST SRMs such as the Adult/Infant Formula SRM and Fortified Cereal SRM. Through initiating and providing guidance for a number of nutrition metrology-related activities, FCMDL will catalyze improvement of the overall measurement system for vitamins. FCMDL will participate as collaborators in method validation studies as appropriate. FCMDL will continue to organize and advise the development and conduct of symposia, and other appropriate workshops.


3.Progress Report
The research program has evolved from focusing on specific method development for determination of vitamins to a broader aspect of improving the overall measurement system for vitamins in foods and supplements. This approach requires the establishment and validation of capability within the Food Composition and Methods Development Laboratory (FCMDL) to make high quality measurements of vitamins, and then to apply this capability to specific projects, including generating definitive data in collaboration with the National Institute of Standards and Technology (NIST) to provide appropriate new Standard Reference Materials (SRM) for this measurement system.

The FCMDL liquid chromatography/ultraviolet/fluorometric/mass spectrometry (LC/UV/FL/MS) method for Vitamin B6 has been chosen by an AOAC Expert Review Panel to be included for development as a “World Class” method for vitamin analysis in dietary supplements. A method for vitamin B12, collaboratively developed by FCMDL with the Department of Food Safety and Nutrition, National Institute of Health, Lisbon, Portugal, was also considered by this expert panel. Definitive data from FCMDL was utilized to assign values for water soluble vitamins (WSV) and vitamin D to the new Standard Reference Material 1849 Infant/Adult formula released by NIST in July 2009. Initial results have been generated to compare a variety of extraction techniques for vitamins in dietary supplements and fortified cereals.

Vitamin-fortified cereal samples collected regionally for the USDA National Food and Nutrient Analysis Program (NFNAP) have been analyzed for WSV content. Almost all cereal samples analyzed had vitamin levels significantly higher than label-claim values, in line with general manufacturing practice of over-fortifying to provide adequate shelf life.

The improved vitamin D method which combined the extraction procedure from AOAC 992.26 with the chromatographic system from AOAC 2002.05 previously developed for food analysis was modified recently to allow analysis of vitamin D2 in mushrooms. Vitamin D3 was used as an internal standard for quantification of vitamin D2, and samples were run with and without internal standard to allow the small amount of endogenous vitamin D3 to be determined along with vitamin D2.


6.Technology Transfer

None

Review Publications
Chen, P., Atkinson, R.L., Wolf, W.R. 2009. Single lab validation of a LC/UV/FLD/MS method for simultaneous determination of water-soluble vitamins in multi-vitamin dietary supplements. Journal of the Association of Official Analytical Chemists. 92(2):680-688.

Last Modified: 8/30/2014
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