4. CALCULATION OF CATALYTIC ACTIVITY CONCENTRATION
For routine determination of the catalytic activity concent–
ration of ALAT
in serum corrections for reagent and sample
blank rates may be omitted.
4.1 Molar absorption Coefficient of the Monitored Product
The
m~lar ab~<[rption coefficien~s
of NAQt_r are:
618 m x
~ol
a! 1 334 nm, 630 m x mol
at 340 nm,
and 340 m
x
mol
at 365 nm.
4.2 Calculation at eonstant Pathlength
Using measurement at
340
rum
as an example,
the catalytic ac–
tivity concentration of ALAT is calculated as follows:
Symbol
Type of quantity
b
d
Catalytic activity concentration
Decrease of (decadic) 340 nm absorbance
per seeond
Molar 340 nm absorption coefficient of
NADH
=
630
Light pathlength (0.01)
l
v
sample volume fraction: 0.0833
vol(L)/vol(L)
4.2.1 Calculation for a Pathlength of
0.01
m
d
d
b=
=
c
x
l
x
v
630
x
0.01
x
0.08333
d
b=
=
d
x
1.905
0.525
b=
d
l.
905
x
kat/m
3
x
b=
d
x
1905
x
pkat/L
Calculated for a Measuring !}me
o~
1
60
s:
b
=
d
x
1905
x
pmol
x
(60s)
x
L
b
=
d
x
1905
U/L
b
d
x
31.75
ykat/L
x
m
x
To
~onvert
fromykat / l to U/ L multiply by 60.
To convert from U/ L toykat / L diviqe by 60.
Klinisk kemi i Norden 2: suppl. 1990
2
Uni
t
pkat/L
-l
s
m
2
x
mol-l
m
l
-l s
-l
x
mol
x
m
mol
-l
x
s
3 m
67
