Certification of fat-soluble vitamins, carotenoids, and cholesterol in human serum: Standard Reference Material 968b.

In Standard Reference Material 968b, fat-soluble vitamins and cholesterol in human serum, certified values are provided for cholesterol, retinol, retinyl palmitate, alpha-tocopherol, trans-beta-carotene, total beta-carotene ( trans plus cis isomers), total alpha-carotene, and lutein. Non-certified values are also reported for gamma-tocopherol (includes beta-tocopherol), delta-tocopherol, zeaxanthin, beta-cryptoxanthin, trans-lycopene, trans-lycopene, trans-alpha-carotene, total lycopene, 9- cis-betacarotene, 13- plus 15- cis-beta-carotene, and 15- cis-beta-carotene. Both certified and non-certified values are based on the agreement among results from three different liquid chromatographic analytical procedures developed at NIST and from an interlaboratory comparison exercise among institutions that participate in a NIST-managed Micronutrients Measurement Quality Assurance Program. Cholesterol is certified in this material using the NIST isotope dilution/mass spectrometric definitive method.