Photometric Assay of Plasma Heparin. ∗

Abstract

Summary

A photometric assay of heparin sodium is described. This consists of a preliminary precipitation of 5 ml of plasma with n-octylamine, reprecipitation with zinc hydroxide, decomposition of this precipitate with phosphate buffer solution, and final precipitation with toluidine blue O. After washing, the red-purple residue is taken up in alkaline alcohol and read photometrically. The heparin is a component of the red-purple dye precipitate. Normal plasma contains non-active heparin-like substances, amounting to 0.02 to 0.54 mg%. Added heparin sodium to plasma is quantitatively recovered. Intravenous heparin sodium and “depo-heparin” levels follow the clotting inhibition effects. Normal urines contain from 3 to 12 mg% of non-active metachromatic substance expressed as heparin sodium. Heparin sodium added to urine may be recovered.