Effects of the drug Disulphine Blue on routine biochemical investigations

Major interference by Disulphine Blue in the colorimetric determination of amylase, albumin, protein, iron and total iron-binding capacity is described. The drug, an intense blue dye, was administered intravenously to a patient before surgery to allow demarcation of devitalised bone. Successive sampling showed the drug to have a half-life of 30 hours, to remain visible for 150 hours in both urine and blood, and to cause significant interference with the five analytes for up to 21/2 days. The 640 nm absorbance peak of Disulphine Blue was shown to be pH-dependent, and therefore the reaction conditions of individual methods may influence the degree of interference.