Source: AGRICULTURAL RESEARCH SERVICE submitted to NRP
DETERMINATION OF SELECTED TRACE ELEMENTS AND ELEMENTAL SPECIES IN FOODS
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
0405707
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Jul 16, 2002
Project End Date
Feb 21, 2004
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
AGRICULTURAL RESEARCH SERVICE
RM 331, BLDG 003, BARC-W
BELTSVILLE,MD 20705-2351
Performing Department
(N/A)
Non Technical Summary
(N/A)
Animal Health Component
50%
Research Effort Categories
Basic
0%
Applied
50%
Developmental
50%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
70150102000100%
Knowledge Area
701 - Nutrient Composition of Food;

Subject Of Investigation
5010 - Food;

Field Of Science
2000 - Chemistry;
Goals / Objectives
Develop single and multielement methods for determination of trace elements of nutritional and health concern; Develop new/improved methods permitting direct analysis of solids by graphite furnace atomic absorption spectrometry and electrothermal vaporization inductively coupled plasma mass spectrometry; Develop methods for determination of different chemical forms of nutritionally important elements (e.g. Fe, Se, Co, K and Cr).
Project Methods
Graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and ICP-mass spectrometry (ICP-MS) will be used to develop robust validated single element and multielement methods for health-related elements such as Co and Cr (in addition to those elements normally studied: Mn, Zn, Fe, Cu, Mg, Ca, Na, K, P). Methods will be peer validated to gain official status, recognition and facilitate technology transfer. A primary focus will be direct solids analysis using ultrasonic slurry sampling with both electrothermal vaporization ICP-MS (USS-ETV-ICP-MS) and USS-GFAAS. An international collaborative study will be conducted using a specified method for analysis of 4 different slurries. To facilitate chemical speciation measurements, capillary zone electrophoresis (CZE) will be coupled with ICP-MS. Also a 2-step furnace will be used to thermally separate suitable species. Multielement GFAAS will be compared with a commercial ICP-MS system to assess the strength/weakness of each approach.

Progress 07/16/02 to 02/21/04

Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Trace elements play a major role in human metabolism and food composition data are needed to ensure health promotion and disease prevention. In addition, there is a need for chemical speciation data because the metabolism and bioavailability of an element is very often dependent on the exact chemical form. At the present time, methods for those elements which are present at lower concentrations are often not sensitive enough. Recent reviews of food composition databases indicate there is a lack of high quality elemental food composition data and there is almost no data for metal species. We are developing single element and multielement methods for determining trace metals using: inductively coupled plasma- atomic emission spectrometry (ICP-AES), inductively coupled plasma-mass spectrometry (ICP-MS) and graphite furnace-atomic absorption spectrometry (GF-AAS). For speciation measurements, a separation method and an elemental detection method must be combined. This has been done at the Food Composition Laboratory by coupling capillary electrophoresis (CE), gas chromatography (GC), and high pressure liquid chromatography (HPLC) to the detector systems described above. Nutritional science now focuses on optimum dietary intakes for health maintenance and reduced disease risk. As such, there is interest in the establishment of nutrient databases that allow evaluation of requirements and bioavailability of food components and their effect on health. The lack of rugged and accurate analytical methodology for trace element data is a serious problem because the analytical community which produces food composition data relies heavily on the use of official analytical methods from organizations such as AOAC (Association of Official Analytical Chemists), ILSI (International Life Sciences Institute), etc. The current lack of methods for chemical speciation poses problems to nutritionists and medical professionals as they try to diagnose diseases and develop strategies for health promotion. The research to be undertaken falls under National Program 107 - Human Nutrition and addresses performance goal 3.1.2.B as described in the National Program Action Plan. Goal 3.1.2 is "Food Composition and Consumption: Develop techniques for determining food composition, maintain national food composition databases, monitor the food and nutrient consumption of the U.S. population, and develop and transfer effective nutrition intervention strategies." This project directly addresses Priority Objective B. Develop Analytical Methodology for Nutrients. This research will benefit the field of analytical chemistry, the medical community, and the general public. New and/or improved analytical methods will provide data on nutrients and bioactive compounds found in foods, will provide medical and nutrition researchers with data necessary to evaluate the efficacy of a variety of food components, and will expand the National Nutrient Database for Standard Reference which is on the Web and available to anyone in the U.S. or the world. 2. List the milestones (indicators of progress) from your Project Plan. There were no milestones when the original CRIS project was developed. The objectives were to: Develop robust single element and multi-element methods for determination of trace elements of nutritional and health concern. Develop new/improved methods for direct analysis of solids by ultrasonic slurry sampling with graphite furnace atomic absorption spectrometry and electrothermal vaporization inductively coupled plasma mass spectrometry. Develop methods for the determination of different chemical forms of nutritionally important elements. 3. Milestones: A: List the milestones (from the list in Question #2) that were scheduled to be addressed in FY 2004. How many milestones did you fully or substantially meet in FY 2004 and indicate which ones were not fully or substantially met, briefly explain why not, and your plans to do so. All of the objectives were met. B. List the milestones (from the list in Question #2) that you expect to address over the next 3 years (FY 2005, 2006, & 2007). What do you expect to accomplish, year by year, over the next 3 years under each milestone? None, this CRIS was terminated in September of 2003. 4. What were the most significant accomplishments this past year? A. Single most significant accomplishment during FY 2004: CRIS 1235-52000-040-00D was a bridging project for CRIS 1235-52000-034- 00D (Determination of selected trace elements and elemental species in foods) which expired 7/16/02. The bridging CRIS was replaced by a new CRIS 1235-52000-046-00D (Development of analytical methods for trace elements and elemental species in foods). We received notification from Office of Scientific Quality Review (OSQR) of our score (6 - minor revision) for the new CRIS in September 2003 and the letter of certification from the Dr. Johnson in December 2003. We have conducted research based on the new CRIS objectives since september 2003. Consequently, all research has been reported under the new project, CRIS 1235-52000-046-00D. B. Other significant accomplishments: None. C. Significant accomplishments/activities that support special target population: None. D. Progress Report: None. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. A brief summation of the research covered by CRIS 1235-52000-034-00D and CRIS 1235-52000-040-00D from 10/01/97 through 9/30/03 is listed below. A multielement ICP-MS method was developed for the simultaneous determination of 13 elements (Na, Mg, P, K, Ca , V, Cr, Fe, Mn, Co, Ni, Cu, and Zn) in water samples. This method was used in collaboration with Nutrient Data Laboratory for the determination of trace elements in municipal water supplies and bottled waters as well as soft drinks. These data permit accurate assessment of trace elements in U.S. diets. Ultrasonic slurry sampling was used to characterize the homogeneity of a variety of metals at the mg and sub-mg level in NIST reference materials SRM 1548a Mixed Diet and RM 8431 Total Diet. RSDs better than 3% (for elements including Mn, Cu, Fe and Ni) at the 1 mg level were achieved. This research enhances the value of the reference materials, demonstrating their homogeneity at the mg level (typical certificates recommend a minimum mass of 250 mg). This technology has made a significant impact on the analytical community and resulted in numerous publications related to direct analysis of solid samples. An analytical method suitable for the detection of metallo-thioneins as well as cobalamin (Vitamin B-12), was designed and tested, based on CE- ICP-MS. Optimal separation of four cobalamin species (cyanocobalamin, hydroxocobalamin, methylcobalamin, and 5'-deoxyadenosylcobalamin) and a potentially harmful corrinoid analogue (cobinamide dicyanide) was obtained using 20 mM formate buffer at a pH of 2.5. Solution detection limits were approximately 50 ng/mL (corresponding to approximately 4 ng of cobalt). A rapid screening method was developed for the determination of cyanocobalamin in fortified foods and supplements and results were achieved in less than 10 minutes. These methods will permit more accurate assessment of the forms of Vitamin B-12 found in foods. HPLC methods were developed for the quantification of four iron- containing proteins (hemoglobin, myoglobin, ferritin and transferrin) found in foods. Size exclusion and hydrophobic interaction chromatography were combined with UV/Vis and flame AAS sequential detection to provide species specific information. This research addressed problems related to the lack of high purity Fe species specific standards. This method has the potential for supplying simultaneous values for heme and non-heme iron in foods. A method for the determination of selenomethionine (SeMet) was developed which is based on a "textbook" reaction with cyanogen bromide to cleave proteins at methionine. This reaction occurs similarly for SeMet and results in a methylthio(seleno) cyanide reaction product that can be quantified by GC-MS. Use of 74Se isotopically labeled SeMet as an internal standard allows accurate quantification and high precision. This method will be used to characterize SeMet content of various type of wheat, an important source of dietary Se.

Impacts
(N/A)

Publications

  • Miller-Ihli, N.J., Pehrsson, P.R., Cutrufelli, R.L., Holden, J.M. Fluoride content of municipal water in the United States: What percentage is fluoridated? Journal of Food Composition and Analysis. 2003. v.16(5). p. 615-622.
  • Yanes Santos, E.G., Miller-Ihli, N.J. Characterization of microconcentric nebulizer uptake rates for capillary electrophoresis inductively coupled plasma mass spectrometry. Spectrochimica Acta. 58:949-955
  • Miller-Ihli, N.J. CE-ICP-MS and ETV-ICP-MS: Microsmples are a reality. Pittcon 2003. March 9-14, 2003, Orlando, Florida. Paper #1000-3.


Progress 10/01/02 to 09/30/03

Outputs
1. What major problem or issue is being resolved and how are you resolving it? Trace elements play a major role in human metabolism and food composition data are needed to ensure health promotion and disease prevention. In addition, there is a need for chemical speciation data because the metabolism and bioavailability of an element is very often dependent on the exact chemical form. At the present time, methods for those elements which are present at lower concentrations are often not sensitive enough. Recent reviews of food composition data bases indicate there is a lack of high quality elemental food composition data and there is almost no data for metal species. We are developing single element and multielement methods for determining trace metals using: inductively coupled plasma- atomic emission spectrometry (ICP-AES), inductively coupled plasma-mass spectrometry (ICP-MS) and graphite furnace-atomic absorption spectrometry (GF-AAS). For speciation measurements, a separation method and an elemental detection method must be combined. This has been done at the Food Composition Laboratory (FCL) by coupling capillary electrophoresis (CE), gas chromatography (GC), and high pressure liquid chromatography (HPLC) to the detector systems described above. 2. How serious is the problem? Why does it matter? Nutritional science now focuses on optimum dietary intakes for health maintenance and reduced disease risk. As such, there is interest in the establishment of nutrient databases that allow evaluation of requirements and bioavailability of food components and their effect on health. The lack of rugged and accurate analytical methodology for trace element data is a serious problem because the analytical community which produces food composition data relies heavily on the use of official analytical methods from organizations such as AOAC (Association of Official Analytical Chemists), ILSI (International Life Sciences Institute), etc. The current lack of methods for chemical speciation poses problems to nutritionists and medical professionals as they try to diagnose diseases and develop strategies for health promotion. 3. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? This program meets the need described under National Program 107, REE General Goal III: A Healthy and Well-Nourished Population Who Have Knowledge, Desire and Means to Make Health Promoting Choices; specifically under Objection 3.1 Nutritious Food with Strategy 3.1.2. for Food Composition and Consumption, among others to develop new methods for measuring selected nutrients and food components, and to transfer new measurement techniques and data to users. 4. What were the most significant accomplishments this past year? A. Single Most Significant Accomplishment During FY 2003: Methods are needed to measure individual species of vitamin B12, because absorption and bioavailability are dependent on the chemical form or species. Scientists in Food Composition Laboratory (FCL) have combined micro-separation techniques, including capillary electrophoresis (CE) and micro-high-performance liquid chromatography (micro-HPLC), with element specific detection using inductively coupled plasma mass spectrometry (ICP-MS) to allow the determination of all the individual species. Methods developed have demonstrated that the various species can be separated and quantified at very low levels in a few hours offering a significant improvement over the "official AOAC microbiological method" for B12 which takes several days to complete and which cannot quantify the individual species. Methods developed will offer rapid, multi-species determination of individual cobalamins as well as a very rapid method for cyanocobalamin alone, which is used in supplements and for fortification in the United States. B. Other Significant Accomplishments: Well characterized, high quality reference materials are critical for high accuracy trace element determinations. Scientists in FCL contributed nutritionally important trace element data for the certification of fish tissue reference materials produced by National Institute of Standards and Technology (NIST) and National Food Processors Association (NFPA). We also participated in an inter-laboratory comparison, at the request of the European Commission, providing trace element data for a rice sample. These activities should have a significant positive impact on food composition data quality. C. Significant Accomplishments/Activities that Support Special Target Populations: None. D. Progress Report: Determination of Fe species in meats. A method based on size exclusion chromatography and tandem detection (UV/Vis spectrophotometry and flame atomic absorption spectrometry) has been developed that allows for the determination of Fe as hemoprotein (hemoglobin or myoglobin). Material balance studies have shown that all the hemoprotein is extracted and that the remainder of the Fe is accounted for in the extraction solution or the solid. A second method is being developed to determine heme Fe, Fe in the porphyrin ring with the globin protein removed. These two methods, coupled with the determination of total Fe, using conventional sample digestion and flame AAS, will provide clarification as to the availability of the hemoprotein Fe and heme Fe species for absorption in the intestine. This methodology will ultimately be used, in collaboration with the Nutrient Data Laboratory, to establish a database for Fe species in foods. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. 1) A multi-element ICP-MS method was developed for the simultaneous determination of 13 elements (Na, Mg, P, K, Ca , V, Cr, Fe, Mn, Co, Ni, Cu, and Zn) in water samples. This method was used in collaboration with Nutrient Data Laboratory for the determination of trace elements in municipal water supplies and bottled waters as well as soft drinks. These data permit accurate assessment of trace elements in U.S. diets. 2) Ultrasonic slurry sampling was used to characterize the homogeneity of a variety of metals at the mg and sub-mg level in NIST reference materials SRM 1548a Mixed Diet and RM 8431 Total Diet. RSDs better than 3% (for elements including Mn, Cu, Fe and Ni) at the 1 mg level were achieved. This research enhances the value of the reference materials, demonstrating their homogeneity at the mg level (typical certificates recommend a minimum mass of 250 mg). This technology has made a significant impact on the analytical community and resulted in numerous publications related to direct analysis of solid samples. 3) An analytical method suitable for the detection of metallo-thioneins as well as cobalamin (Vitamin B-12), was designed and tested, based on CE- ICP-MS. Optimal separation of four cobalamin species (cyanocobalamin, hydroxocobalamin, methylcobalamin, and 5'-deoxyadenosylcobalamin) and a potentially harmful corrinoid analogue (cobinamide dicyanide) was obtained using 20 mM formate buffer at a pH of 2.5. Solution detection limits were approximately 50 ng/mL (corresponding to approximately 4 ng of cobalt). A rapid screening method was developed for the determination of cyanocobalamin in fortified foods and supplements and results were achieved in less than 10 minutes. These methods will permit more accurate assessment of the forms of vitamin B-12 found in foods. 4) HPLC methods were developed for the quantification of four iron containing proteins (hemoglobin, myoglobin, ferritin and transferrin) found in foods. Size exclusion and hydrophobic interaction chromatography were combined with UV/Vis and flame AAS sequential detection to provide species specific information. This research addressed problems related to the lack of high purity Fe species specific standards. This method has the potential for supplying simultaneous values for heme and non-heme iron in foods. 5) A method for the determination of selenomethionine (SeMet) was developed which is based on a "textbook" reaction with cyanogen bromide to cleave proteins at methionine. This reaction occurs similarly for SeMet and results in a methylthio(seleno) cyanide reaction product that can be quantified by Gas Chromatography-Mass Spectrometry, (GC-MS). Use of 74Se isotopically labeled SeMet as an internal standard allows accurate quantification and high precision. This method will be used to characterize SeMet content of various type of wheat, an important source of dietary Se. 6. What do you expect to accomplish, year by year, over the next 3 years? This project will be replaced by a new project that is currently being peer reviewed. The new project is not yet approved by Office of Scientific Quality Review (OSQR).

Impacts
(N/A)

Publications

  • Miller-Ihli, N.J., Pehrsson, P.R., Cutrufelli, R.L., Holden, J.M. Fluoride content of municipal water in the United States: What percentage is fluoridated? Journal of Food Composition and Analysis. 2003. v.16(5). p. 615-622.
  • Yanes Santos, E.G., Miller-Ihli, N.J. Characterization of microconcentric nebulizer uptake rates for capillary electrophoresis inductively coupled plasma mass spectrometry. Spectrochimica Acta. 58:949-955
  • Miller-Ihli, N.J. CE-ICP-MS and ETV-ICP-MS: Microsmples are a reality. Pittcon 2003. March 9-14, 2003, Orlando, Florida. Paper #1000-3.