CL-10 Plus – User Manual
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ECPUS vers 0.2 eng
2)
SLOPE
.
Second step: run of an analysis cycle injecting 25
µ
L of urea standard (100 mg/dL):
D1: both the electrodes contain the same solution, standard, and their pH difference
is always approx. the same, 20
∆
mpH.
D2: EL 1 contains standard, EL 2 st urease enzyme, which
promotes the reaction:
DL1 = D2 - D1 = 30 - 20 = 10
∆
mpH
But, also in this case, not all the 10
∆
mpH are caused by the urea hydrolysis, we have to
subtract 1
∆
mpH, the “acidity” of urease:
STD 100 mg/dL: 10 - 1 = 9
∆
mpH.
Correcting to 100/9 = 11.11 mg/mpH [slope value].
The instrument, after calibration, will store in the method settings the OFFSET and SLOPE
values and calculate the concentration (of the samples unknown) according to the formula
[sample] = [
∆
mpH sample - offset] * slope
∆
mpH
t (s)
20
5
30
21
(DL1)
30
D1 time
D2 time
