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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

2013 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:
A “dilute and shoot” method developed at FCMDL for the determination of vitamin D as well as triacylglycerols (TAGs) in the excipient oil in dietary supplement gelatin capsules was improved and expanded (see Accomplishment). The method was used to survey the vitamin D content of various oil-filled dietary supplements. Data are being processed and prepared for publication.

A new method for the quantification of TAGs was developed based on response factors obtained from the comparison of HPLC-MS results with those obtained by gas chromatography with flame ionization detection (GC-FID). AOCS method Ce-1b-89 was implemented for GC-FID analysis but required modification and improvement to allow the very long chain fatty acid methyl esters to elute. GC-FID data were obtained for all oils in the dietary supplements (olive oil, soybean oil, sunflower oil, safflower oil, rice bran oil, canola oil) for comparison to results by LC-MS. A manuscript describing this new development has been submitted and is undergoing the first stage of review.

The “dilute and shoot” method was applied to the analysis of solid powdered dietary supplement capsules and NIST SRM 3280 compressed powder supplement tablets. The “dilute and shoot” method was also applied to the determination of vitamin D in irradiated mushroom powders. Preliminary data suggests that this approach is feasible for solid samples and further research will be included in the new project goals.


4.Accomplishments
1. A quadruple parallel mass spectrometer. Scientists at USDA in Beltsville, MD, have developed a “quadruple parallel mass spectrometer” for the analysis of vitamin D and triacylglycerols (TAGs) in dietary supplements. The instrumental design employs high performance liquid chromatography with seven detectors, including four mass spectrometer, for the identification and quantification of vitamin D3 and the TAGs in the oil. The data from these experiments allow a much higher degree of confidence in quantitative results, because multiple instruments acquire qualitative information on the same samples at the same time, in parallel. This represents a new ‘high water mark’ for mass spectrometry that demonstrates a unique capability here at FCMDL that no one else currently possesses.


Review Publications
Byrdwell, W.C., Horst, R.L., Phillips, K.M., Holden, J.M., Patterson, K.Y., Harnly, J.M., Exler, J. 2013. Vitamin D levels in fish and shellfish determined by liquid chromatography with ultraviolet detection and mass spectrometry. Journal of Food Composition and Analysis. 10:1016/j.jfca.2013.01.005.

Last Modified: 7/22/2014
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