Photometric determination of total protein in lipemic sera

We compared various procedures and biuret reagents suggested for determination of protein in lipemic sera. A modified procedure, consisting of the precipitation of serum protein with acetone and dissolution of the precipitate in a biuret reagent, has been developed. The sample (0.02 ml) is mixed with 0.1 ml of distilled water and 2 ml of acetone. The mixture is shaken, centrifuged, and the precipitate dissolved in 1.5 ml of ethylenediaminete-traacetate-chelated biuret reagent. This method is suitable for both clear and lipemic sera. Values obtained with the procedure proposed are in good agreement with values by the Kjeldahl method.