Chemistry Parameters
Calculation Factor
User Defined Reagents
UniCel DxC Systems Instructions For Use A13914
Page 9-8
October 2005
Calculation Factor
A calculation factor should be entered if no calibrators are defined. If a calculation
factor is not defined, the system will not accept the default value of 0, and the user
must type 1. For downgoing reactions, the entry must be a negative number.
Additional slope and offset adjustments may be made at the Reagent Status/
Calibration Status screen.
For calculating the appropriate factor for rate chemistries, a derivation of the Beer's
Law formula as applied to bichromatic chemistries can be used as follows:
where:
e
1
=
The extinction coefficient of the chromophore at the primary
wavelength.
e
2
=
The extinction coefficient of the chromophore at the
secondary wavelength.
Extinction coefficients for the chromophore MUST be obtained from the
reagent manufacturer or determined experimentally (refer to
Determination of Extinction Coefficients
T.V.
=
Total reaction volume (sample plus reagent, µL)
S.V.
=
Sample volume (µL)
0.5
=
Cuvette pathlength (cm)
1000
=
Units correction factor
Table 9.10
Allowable Entries for a Calculation Factor
-99999.000 to 99999.000, except 0
E014426L.EPS
×
0.5
(e
1
– e
2
)
1000
S.V.
T.V.
