Thermo Scientific VSTAR-ISE, Справочное руководство

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Thermo Scientific Orion VERSA STAR pH/ISE/Temperature Module
Multipoint Calibration Curve Feature
The Orion VERSA STAR Meter with pH/ISE/Temperature module systems utilize a point-to-point scheme for multipoint
calibrations in the pH and ISE modes. 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 or concentration 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.