Optothermal measurement of haemoglobin in blood.

A prototype instrument based on optothermal spectroscopy has been developed for determining the haemoglobin content of blood. The optothermal detector is described and consists essentially of a thin sapphire disc glued to a piezoelectric ring. The optothermal instrument is also described. The results of clinical tests using 616 blood samples show excellent agreement with the standard cyanmethemoglobin method and a reproducibility of better than +/- 2%.