"Little Adjustment of Lowry and Biuret Methods to Get Better Absorbance of Proteins"

Abstract

Copper sulfate has been staying as a major source of Cu 2+ for copper based colorimetric protein determinations. Hemi-penta hydrated Copper nitrate furnish Cu 2+ ions which can be used as an alternative to Penta hydrated Copper sulfate in Copper based colorimetric protein determinations. We describe herein the development of a new modified Lowry and Biuret procedures which replace penta-hydrated Copper sulfate of the original reagents (Cu SO 4 .5H 2 O) by hemi penta-hydrated Copper nitrate (Cu 2 (NO 3) 2 2.5 H 2 O). Those methods were applied for measuring different standard samples of protein. We favorably compared the modified methods with the original Lowry and Biuret methods for reliability, assay time and resistance by interferences of non-proteinaceous compounds. Those modified methods showed better reliability, rapid assay time of color development and strong resistance of interfering substances. The modified procedures might be applicable as better options for the determination of protein in a biological sample.