Molar absorptivities of bilirubin (NIST SRM 916a) and its neutral and alkaline azopigments.
Three laboratories in the U.S. and two in the Netherlands determined molar absorptivities (epsilon) of Standard Reference Material (SRM) 916a Bilirubin from the National Institute of Standards and Technology. In caffeine reagent the average epsilon values were 50,060 and 48, 980 L.mol-1.cm-1 at 432 and 457 nm, respectively. The epsilon value of the blue azopigment, obtained with the Reference Method for total serum bilirubin, was 76,490 L.mol-1.cm-1 at 598 nm. When the addition of alkaline tartrate was omitted, the molar absorptivity of the red azopigment was 56,600 L.mol-1.cm-1 at 530 nm.
Department of Pathology, Medical College of Wisconsin, Milwaukee 53226.
B T
BT
Doumas
B W
BW
Perry
R B
RB
McComb
A
A
Kessner
H L
HL
Vader
K L
KL
Vink
J C
JC
Koedam
R C
RC
Paule
D001391:Azo Compounds / Q000032:analysis*; D001663:Bilirubin / Q000032:analysis* / Q000592:standards; D002624:Chemistry, Clinical / Q000592:standards*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007753:Laboratories / Q000592:standards; D012015:Reference Standards; D013053:Spectrophotometry / Q000592:standards
D001391:Azo Compounds; D007202:Indicators and Reagents; D001663:Bilirubin