4.2.2 Calculation for Other Pathlengths and for Other Volume
Fractions
Insert the pathlength (unit: meter) and the volume fraction
(unit L) in the equation instead of the figures given above.
4.3 Calculation at Variable Pathlengths (longitudinal
measurement)
Certain (centrifugal) analyzers measure
longitudinally
through the cuvettes. The pathlength thus becomes proportio–
nal to the total assay volume in the cuvette. Dilution of the
assay medium in the cuvettes with an inactive fluid eauses a
corresponding elongation of the pathlength, and the absorban–
ce remains constant. The net effect is that the calculation
factor becomes proportional to the sample volume and indepen–
dent of the sample volume fraction in the cuvette. (Ref. 34,
CK) In the example below the sample volume is
30
uL.
Symbols Type of quantity
a
Area of cuvette end
v
d
Sample volume
Equals decrease in absorb–
ance at 340
nrn
per seeond
Other symbols as given above
Exarop
le
0.25
x
10-
4
30
x
10-
6
Uni
t
2
m
L
-l
s
d
x a
d
x
0.25
x
10-
4
-l
2
b=
b=
b=
b=
=
€
x v
630
x
30
x
l0- 6
d
x
25
189000
d
x
0.001323
x
kat/L
d x 1323 pJcat/L
Calculated for a Measuring Time of
60
s:
b=
d
x
1323 U/L
b
=
d x 22.05 ykat/L
x
x
s
x m
2
-l
m
x
mol
mol
x
s
L
x L
-l
68
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