EKF Diagnostics Biosen C-Line GP+ - Page 57

Theoretical priciples
User Manual Biosen C_line Clinic / GP+
53
Figure 32 – Glucose-lactate-principle
The resulting current is proportional to the glucose/lactate concentration.
Unknown glucose/lactate concentrations can be determined relative to a
calibration with a solution of known concentration. After each
measurement the chip sensor is automatically cleaned with a buffer
solution. This washes out the old sample substance. The sensor system
is then ready for the next measurement.
15.3 Calibration
The calibration of the device takes place shortly before measurement.
To this end, a glucose/lactate solution of known concentration
(12mmol/l, thinned 1:51) is measured on the device. The measured
current signal and the corresponding glucose/lactate concentration are
used as base for calculation of unknown concentrations as
concentration and current signal are changing proportionally.
The value of the calibrator for glucose is traceable to NIST (National
Institute of Standards & Technology, Gaithersburg USA) Standard
Reference Material 917d (D-Glucose).
immobilized
glucose oxidase
glucose
L-lactate
other substances in blood
other substances in blood
immobilized
lactate oxidase
amperometric
H
2
O
2
-determination
amperometric
H
2
O
2
- determination
current signal
current signal
ß-D-glucose+
O
2
+H
2
O

D-gluconic acid
+H
2
O
2
H
2
O
2
2H
+
+O
2
+2e
H
2
O
2
2H
+
+O
2
+2e
L-Lactate+O
2

pyruvate+H
2
O
2