2009 Annual Report
1a.Objectives (from AD-416)
1) Develop robust multi-element methods and quality control materials for trace and ultratrace elements important to human health,.
2)develop method for total vitamin B12 in foods,.
3)develop elemental speciation methods for vitamin B12 (cobalamin),.
4)develop analytical methods for the determination of hemeprotein and heme Fe in meats, and.
5)develop elemental fingerprinting method for food and botanical materials.
1b.Approach (from AD-416)
Analytical methods for the trace and ultratrace elements will be based on graphite furnace atomic-absorption spectrometry (GF-AAS), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and ICP-mass spectrometry (ICP-MS). Total vitamin B12 and heme Fe will be determined using selective extraction and ICP-AES. Speciation of vitamin B12 will be based on capillary electrophoresis ICP-MS. Elemental fingerprinting methods will use semi-quantitative ICP-MS.
Over the five year period of this project, methods were developed and/or modified for the determination of trace elements in foods and biological materials using flame and graphite furnace atomic absorption spectrometry (FAAS and GF-AAS), inductively coupled plasma-atomic emission spectrometry (ICP-AES), and ICP-mass spectrometry (ICP-MS). Instrumental modifications were developed for coupling liquid chromatography and capillary electrophoresis to the ICP-MS. These methods were important for the support of on-going research on trace element content in foods and their organic complexes. In 2004, the Food Composition and Methods Development Laboratory (FCMDL) collaborated with the National Food Processors (NFP) Analytical Chemistry Subcommittee to develop more robust trace element methods. In 2006, FCMDL collaborated with the National Institute of Standards and Technology (NIST) to determining the concentration of aluminum (Al) in a bovine serum Standard Reference Material using GF-AAS. Subsequent research demonstrated that calcium (Ca) in soy milk settled out with time and was difficult to re-dissolve. Additional collaboration with NIST scientists characterized trace elements in a multivitamin/multielement Standard Reference Material (SRM 3280). Development of a method for profiling the trace element content of plant materials using the full scan mode (90 elements) of the ICP-MS was undertaken.
A method for the determination of iron in a porphoryn complex (heme Fe) based on the classic Hornsey extraction method using acidified acetone was developed. The concentration of heme Fe is of importance since it is absorbed by a different process than dietary inorganic Fe. A size exclusion chromatography-FAAS instrument for detection of Fe eluting as myoglobin, hemoglobin, ferritin, and transferrin was developed. Scientists collaborated with the Plant, Soil, and Nutrition Lab (USDA, Ithica, NY) on the evaluation of cooking on the bioavailability of Fe. The results indicated that 100% of the hemoglobin and myoglobin are denatured (and thus the protein and heme Fe separate) at 140 degrees F and that 30% of the heme form of Fe is destroyed during cooking.
Beecher, G., Stewart, K., Holden, J.M., Harnly, J.M., Wolf, W.R. 2009. Legacy of Wilbur O. Atwater: human nutrition research expansion at the USDA-interagency development of food composition research. Journal of Nutrition. 139:178-184.