Automated cyanide-free method for haemoglobin determination on Technicon H.1

We have developed a cyanide-free haemoglobin method for our Technicon H.1 counter. By adding 2.5 mmol/l of the ionic surfactant sodium dodecyl sulphate in 154 mmol/l sodium chloride, the haemoglobins are converted to a stable product, denatured globin haemichrome, within the 25 s available on the instrument. The method is as precise and accurate as the original H.1 method, and the reagent is easily made in the laboratory at a very low price. Since the method is relatively safe with regard to waste disposal, the effluent from the counter can be drained into the laboratory sink. The method, a 'SDS-haemichrome method', has now worked very satisfactorily in routine use for a year. Manufacturers of haematological analysers should consider this haemoglobin method for their automated instruments.