Hemoglobin (Hb or Hgb) is a globular protein found primarily in erythrocytes that carries oxygen from the lungs to tissue where it releases oxygen and then returns carbon dioxide (CO2) from the tissue to the lungs. Hemoglobin also binds CO2, carbon monoxide (CO), and nitric oxide (NO). Cayman's Hemoglobin Colorimetric Assay provides a quick, reliable method for determining total hemoglobin concentration in a variety of biological samples, including blood, tissue homogenates and cell lysates. Unlike the universally accepted reference method of hemoglobin determination, which uses potassium cyanide as a reagent and commonly under-estimates hemoglobin levels, Cayman's Hemoglobin Colorimetric Assay utilizes an optimized detection reagent which is non-toxic, reporting accurate measurements of total hemoglobin concentrations with an absorbance between 560-590 nm.