Abaxis VetScan vs2 - Rate Methods

Principles of Procedure and Operation 9-3
The equation for calculating absorbance is this:
where:
A = Absorbance at wavelength 1, referenced to wavelength 2
I
O1RC
= Intensity of light transmitted through the reaction cuvette at wavelength 1
I
O2RC
= Intensity of light transmitted through the reaction cuvette at wavelength 2
I
O1
0
= Intensity of light transmitted through the dark cuvette at wavelength 1
I
O2
0
= Intensity of light transmitted through the dark cuvette at wavelength 2
I
O1OC
= Intensity of light transmitted through the open cuvette at wavelength 1
I
O2OC
= Intensity of light transmitted through the open cuvette at wavelength 2
This is the basic equation for measuring analyte concentrations in the rate methods and endpoint
reactions used in chemistries.
Rate Methods
The rate of the reaction is calculated from the difference between absorbances measured at certain
defined intervals on the linear portion of the reaction curve. Absorbances are taken throughout the
read time to confirm the linearity of the reaction curve. The absorbance rates are converted to ana-
lyte concentrations using the rotor-specific calibration factors encoded on the bar code ring.
The equation for rate methods is:
where:
'A/'W = Rate of change of absorbance
F = Measurements taken at time F on linear portion of reaction curve
B = Measurements taken at time B on linear portion of reaction curve
t = Time in minutes
I
OXX
= Other intensities, same as described above
(I
λ1RC
- I
λ1
0
) / (I
λ2RC
- I
λ2
0
)
(I
λ1OC
- I
λ1
0
) / (I
λ2OC
- I
λ2
0
)
A = -log
{
-log
{
-log
F
}
(I
λ1RC
- I
λ1
0
) / (I
λ2RC
- I
λ2
0
)
(I
λ1OC
- I
λ1
0
) / (I
λ2OC
- I
λ2
0
)
B
}
(I
λ1RC
- I
λ1
0
) / (Iλ2RC - I
λ2
0
)
(I
λ1OC
- Iλ1
0
) / (
I
λ2OC - I
λ2
0
)
Time Period