Chromic acid assay for quantification of total lipids in pollen v1

This protocol quantifies total lipid contents of pollen through colorimetric oxidation of lipids by chromic acid (adapted from Amenta, 1970). Small pollen samples (10 mg) are fractured by cell homogenization and lipids are extracted by Folch extraction. Lipid amounts are measured by colorimetric changes when hexavalent (+6 oxidation state) chromium ion is reduced to a trivalent (+3 oxidation state) state during lipid oxidation. The accuracy of the assay depends on how thoroughly the initial extraction excludes non-lipid compounds such as sugars and proteins. A considerable drawback of this method is the toxicity, carcinogenicity, and environmental toxicity of the hexavalent chromium reagents used in this assay. Amenta, J.S. (1970). A rapid extraction and quantification of total lipids and lipid fractions in blood and feces. Clinical Chemistry, 16, 339-346. National Program Number: NP 305 Project Number: 2022-21000-022-000D, 2022-21000-022-053-I Carl Hayden Bee Research Center, USDA-ARS PWA, Tucson, Arizona, USA Grand Challenge - Assessing the Nutrient Contents of Pollen for Bees