Sensitized immunochemical method for the specific detection of human haemoglobin in dried biological samples.

The authors describe a modified version of counterimmunoelectrophoresis of easy performance and high sensitivity. With this method human haemoglobin can easily and specifically be determined either in fresh or dried biological samples. Glutaraldehyde pretreatment of the samples results in the development of complexes with highly favourable electrophoretic mobility and precipitating capacity. By this chemical modification and use of a double set of samples with varying antigen-antibody proportion, the sensitivity of haemoglobin detection in erythrocyte-containing haemolysate and native blood was 300 ng/ml. The examination is easily performed, and without considerable outlay, even with conventional laboratory facilities. It is equally suitable for the detection of occult colorectal bleeding and for species-specific study of blood stains of unknown origin. The authors succeeded in identifying human haemoglobin even in a 42-month dried blood stain.