Optimizing Falling Drop Hemoglobin Method by Comparing Capillary Versus Venous Blood and Determining the Stability of the Copper Sulfate Solution

This study found that capillary blood did not present a more accurate alternative to venous blood in the falling drop hemoglobin test, and copper sulfate did not degrade over 32 weeks at 37.7 °C. This lends support for the current use of venous blood in the test, and for use of copper sulfate solution in tropical climates, where the test is most necessary, with a shelf life of at least 32 weeks.