pH-Sensitive Minisensors
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3.3 Characteristics of a typical pH sensor
The characteristic of a typical sensor are listed below:
Dynamic range: pH 5.5 to 9
Resolution: 0.01 pH
Drift due to bleaching: 0.003 pH per 1000 measuring points
Response time: less then 30 sec
Please note that the given values may differ from your special device and sensoric
application.
3.4 Cross
sensitivities
The optical pH measurement is interfered by ionic strength of the sample. This can be
overcome by a calibration with buffers of ionic strength similar to the sample.
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phas
e
pH
is50
is100
is200
Cross-sensitivity to ionic strength.
A lower ionic strength than used in the calibration will pretend a lower pH and vice versa.
Also small fluorescent molecules like fluorescein can influence the measurement. They will
pretend a higher pH.
We recommend to calibrate the sensor in pH-adjusted media in these cases.