Ultramicro method for serum bilirubin by diazo blue reaction.

ROPER CLINICAL MANAGEMENT of infants with erythroblastosis fetalis necessitates the determination of total serum bilirubin. Of the many modifications of the original diazo reaction on blood serum (1) a micromethod using capillary blood is preferable. One tenth miffiliter of serum was used by Davidson et al. (2) in their modification of the Ernst and F#{246}rster (3) method and by With (4, 5) in his modification of the (alkaline) diazo blue method of Jendrassik and Gr#{244}f (7). Hsia et at. (8) used 0.05 0.1 ml. of serum in a modification of the Malloy and Evelyn (9) method with the microcell attachment of the Evelyn colorimeter. Caraway and Fanger (10) have recently described a modification of the Malloy and Evelyn method using 0.02 ml. of serum in the Beckman DU spectrophotometer with the microadaptation of Lowry and Bessey (11). The method to be described determines the serum bilirubin on 0.02 to 0.05 ml. of serum using the Coleman Junior spectrophotometer.1 It is a modification of the (acid) diazo blue reaction used by Thannhauser and Anderson (12) with precipitation of the serum proteins (13, 14). It has been used successfully in our hospital since 1953.