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Journal of Automatic Chemistry
Volume 11 (1989), Issue 6, Pages 254-259

Comparative interference by haemolysis in automated assays for bilirubin at multiple analyte concentrations

1Department of Pathology, Loyala University Medical Center, Maywood, Illinois 60153, USA
2Department of Biochemistry and Office of Consolidated Laboratory Services—Clinical Chemistry, Rush- Presbyterian-St Luke's Medical Center, Chicago, Illinois 60612, USA

Copyright © 1989 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The negative interference caused by haemolysis in manual bilirubin assays contrasts with the positive interference reported for some automated methods utilizing the same basic chemistry. A comparison was therefore made of the haemolysis interference associated with several automated bilirubin methodologies: multilayer film (Kodak Ektachem- total bilirubin (TBil), direct bilirubin (DBil), conjugated bilirubin (Bc), unconjugated bilirubin (Bu),; tableted reagents (Baxter Paramax- TBil, DBil); continuous flow (Technicon SMAC — TBil). Thirty serum pools were analysed (five concentrations of bilirubin, 2-229 μmol/l; six concentrations of haemoglobin, 0.00002-0.052 mmol/1). All methods, except one (Bc), exhibited both positive and negative interference, depending upon the relative haemoglobin and bilirubin concentrations. This interference, at any given haemoglobin concentration, was neither constant nor proportional with increasing bilirubin concentration. These complex patterns of interference suggest that the best characterization of interference is obtained when (1) both percentage-difference and absolute-difference ‘interferographs’ are plotted; and (2) the interference is determined at multiple analyte concentrations.