Setting up and statistical evaluation of a new haemoglobin assay

A new method for the determination of haemoglobin concentration in human whole blood has been devised. The assay takes advantage of the lysis of erythrocytes that occurs when blood penetrates the pores of a microporous membrane by a strong capillary effect. The released haemoglobin reacts with the reagents previously dried on the membrane, diffuses through the pores of the membrane and produces a uniform coloured spot whose reflectance at 556 nm can be evaluated at the side opposite to that of application of the sample. In the experimental conditions used by authors, a linear relationship was obtained when the reciprocal reflectance was plotted against the haemoglobin concentration. Data obtained by the reflectometric method were compared with reference values on the same samples from centralizedlaboratories. Statistical analysis gave a correlation coefficient of 0.985 and only 4% of all haemoglobin determinations were outside the 95% confidence interval. No interference was observed by haematocrit, erythrocyte count, mean corpuscular volume or mean corpuscular haemoglobin concentration and leukocyte count. This method proved to be useful for rapid, accurate and precise assay of total haemoglobin on both capillary and venous blood.