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Thermo Scientific Orion
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pH with LogR Temperature Module
Electrode Condition Icon
The electrode condition icon indicates the performance of the pH electrode, based on the last saved calibration and
electrode measurement stability.
Icon
pH Electrode Definition of Icon
Electrode condition is good and the electrode slope is 90 to 110 %.
Electrode condition is fair and the electrode slope is 80 to 120 %.
Electrode condition is bad and the electrode slope is less than 80 % or greater
than 120 %.
Consult the electrode user guide for instructions on how to clean, condition and troubleshoot
the electrode.
Multipoint Calibration Curve Feature
The Orion
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Meter and pH with LogR Temperature module systems utilize a point-to-point scheme for
multipoint calibrations in the pH mode. In this technique, straight line segments are drawn between each successive
pair of calibration points. Separate slope and E
0
values are calculated using the adjacent pair of data points.
For example, in a five point calibration, four slopes and five E
0
values are calculated to correspond to the four line
segments that connect the data. pH values for samples are calculated according to the segment that their potential
values fall into.
Those above or below the range of calibration are calculated by extrapolation from the top or bottom most segment.
The displayed slope is an average slope of the separate segments. The slope may be outside the range normally
expected for an electrode. For example, if the slope of one segment is low, then the average will be lower than
theoretical, even though the response may be Nernstian over most of the range.
The figure below is an example of a typical calibration curve using this method.