Studies on the Determination of Bile Pigments - Clinical Chemistry

Vol. 10, No. 5, 1964 DETERMINATION OF UROBILINOGEN 443
Assay of Iirines by the Modified “Quantitative” Procedure
“Pure urobilin” solutions taken through the procedure as described
for urine yielded a mean recovery of 90%. The final colored solutions
were quantitated by comparison with standards not taken through
the extraction procedure and which have been previously described
(5). However, recoveries of urobilin from urine varied erratically
from 50 to 80% of the added urobilin (Table 1).
Precision on normal urines containing low levels of urobilinogen
was poor, with duplicates differing as much as 65%.
Examination of absorption spectra of some reduction mixtures of
urobilin with urine revealed a peak in the 512 m region which was
obtained neither from the reduced urine nor from reduced urobilin
alone (Fig. 2).
Table 1. REcOVERY OF UltomLIN AS UROBILINOGEN FROM PURE SOLUTIONS AND FROM URINE
Added in filtrate Found in filtrate
Urobilin extracted (mg.) extracted (mg.) Recovery (%)
In pure aq. aol.
A 0.065 0.064 99
B 0.060 0.057 95
C 0.065 0.053 82
D 0.063 0.052 83
E 0.089 0.082 92
Added to urine
A 0.105 0.068 65
B 0.095 0.074 78
C 0.095 0.064 67
D 0.091 0.045 49
Urobiinogen
Added to urine 0.150 0.155 103
Fig. 2. Reduction mixtures of
urine (A), urobilin (B), and
urine plus urobilin (C).
a
0
f .100
0
4
450 475
mp