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Project Areas

Nutritional Elements

The FDA requires the content of sodium, calcium, iron, and potassium be provided on the nutritional label of any processed or packaged food sold in the US. In addition, other elements of nutritional interest, such as magnesium, phosphorus, or zinc, may be declared on nutritional labels to bolster or prove the food label or marketing claim. Prior to analytical measurement, the food sample is most often digested in concentrated acid using a microwave or open beaker technique. The NIST approach for elemental analysis includes the addition of internal standards and determination by inductively coupled plasma with optical emission spectrometry (ICP-OES) or with mass spectrometric detection (ICP-MS) [5].  In addition, NIST uses X-ray fluorescence spectrometry (XRF) and the use of  multiple neutron activation analysis techniques, instrumental neutron activation analysis (INAA), radiochemical neutron activation analysis (RNAA), and prompt gamma neutron activation analysis (PGAA), for elemental measurements.  To date, over 35 food-matrix reference materials have been issued with values assigned for nutritional elements. For additional technical information, contact Laura Wood (laura.wood [at] nist.gov).

Water-Soluble Vitamins

Declaration of water-soluble vitamin content is not required on nutritional labels, but many are included as optional values to bolster or prove food label or marketing claims. Water-soluble vitamins may be present in foods in a variety of forms, with varying levels of individual vitamers depending on the type of food product. Prior to analytical measurement, vitamins are extracted from the food sample, which may include weak hydrolysis to release protein- or lipid-bound forms. The NIST approach for water-soluble vitamin measurement includes the addition of labeled vitamins as internal standards and determination by liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) [6, 7, 8]. To date, over 15 food-matrix reference materials have been issued with values assigned for water-soluble vitamins. For additional technical information, contact Melissa Phillips (melissa.phillips [at] nist.gov).

Fat-Soluble Vitamins and Carotenoids

The FDA requires the content of vitamin D be provided on the nutritional label of any processed or packaged food sold in the US. Declaration of other fat-soluble vitamin content is not required on nutritional labels, but many are included as optional values to bolster or prove food label or marketing claims. Fat-soluble vitamins may be present in foods in a variety of forms, with varying levels of individual vitamers depending on the type of food product. Prior to analytical measurement, vitamins are extracted from the food sample, which may include saponification to release lipid-bound forms and/or esters. The NIST approach for fat-soluble vitamin measurement includes the addition of labeled vitamins or related compounds as internal standards and determination by liquid chromatography with absorbance detection (LC-absorbance), with fluorescence detection (LC-fluorescence), or with tandem mass spectrometric detection (LC-MS/MS). To date, over 15 food-matrix reference materials have been issued with values assigned for fat-soluble vitamins. For additional technical information, contact Carolyn Burdette (carolyn.burdette [at] nist.gov).

Fatty Acids

The FDA requires the content of total fat, calories due to fat, and total saturated and trans fats be provided on the nutritional label of any processed or packaged food sold in the US. In addition, other fatty acids of nutritional interest, such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), often are declared on nutritional labels to bolster or prove the food label or marketing claim. Fatty acids are typically present in plant and animal tissues as triglycerides and/or phospholipids, with varying levels of individual fatty acids depending on the type of food product. Prior to analytical measurement, fat is extracted from the food sample, triglycerides and phospholipids are saponified (hydrolyzed) into their free fatty acid components, then all free fatty acids are converted to fatty acid methyl esters (FAMEs). The NIST approach for fatty acid measurement includes the addition of deuterated fatty acids as internal standards and determination by gas chromatography with flame ionization detection (GC-FID) or with mass spectrometric detection (GC‑MS) [9, 10]. To date, over 20 food-matrix reference materials have been issued with values assigned for fatty acids. For additional technical information, contact Ben Place (benjamin.place [at] nist.gov).

Cholesterol

The FDA requires the cholesterol content be provided on the nutritional label of any processed or packaged food sold in the US. Cholesterol is present in animal tissues as free cholesterol and also bound in triglycerides. Prior to analytical measurement, cholesterol is extracted from the food sample, cholesterol esters are saponified (hydrolyzed) into free cholesterol, then derivatized. The NIST approach for cholesterol measurement includes the addition of labeled cholesterol as an internal standard and determination by gas chromatography with mass spectrometric detection (GC‑MS) [11, 12]. Currently, 5 food-matrix reference materials have been issued with values assigned for cholesterol. For additional technical information, contact Melissa Phillips (melissa.phillips [at] nist.gov).

Created June 22, 2020, Updated August 17, 2020