Hemoglobinometry: evaluation of a new method with a stable primary standard.

Using purified chlorohemin as a stable standard, a newly described hemoglobinometry method was evaluated. All blood samples as well as chlorohemin gave identical absorption spectra in an alkaline-detergent solution with a broad peak at 575 nm. Both the reagent mixture and the chlorohemin standard were stable for at least 250 days when stored between 8 degrees C and 32 degrees C in brown glass bottles. The new method showed close correlation when compared to the cyanmethemoglobin technique. Compared to the cyanmethemoglobin method the advantages included a stable standard, shorter conversion time, reduced plasma background and improved hemoglobin ligands conversion. We conclude that the new method confers significant advantages over the cyanmethemoglobin method and in particular provides a stable primary standard with a long shelf-life.