The Lowry protein assay, or Lowry Method, is a biochemical test to measure the amount of protein in a sample. Copper(II) ion in alkaline solution reacts with protein to form complexes, which react with the Folin-phenol reagent, a mixture of phosphotungstic acid and phosphomolybdic acid in phenol. The product becomes reduced to molybdenum/tungsten blue and can be detected colorimetrically by absorbance at 750 nm. The higher the concentration of protein, the darker the solution. Presence of strong acids or ammonium sulfate can interfere with the assay.
