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Calibration
Number of Calibration Points
A 1- or 2-point calibration can be completed for all channels on the TAL-PC and TAL-PE sensors. A 1-point calibration,
typically completed in clear deionized or distilled water, is simply a re-zeroing of the sensor.
Although a 1-point calibration is more convenient (faster and no Rhodamine WT solution is needed), a 1-point
calibration does not reset the second point entered during the most recent 2-point calibration. The consequence is
that error will be alleviated at and near zero, but more error can accumulate in the measurement the farther away from
zero the measured value is. The amount of that error can be different from sensor to sensor, and use case to use case.
It is dependent upon how much that second point may drift, which is not always equivalent to how much the zero point
drifts.
For many users, especially those with sites where pigment is rarely detected and values are at or near zero most of the
time, the far-from-zero accumulation of error is a non-issue. For others, a 1-point calibration should be viewed as a
procedure that will yield semi-quantitative data in the region of the second calibration point.
Users will often perform a calibration check in water to assess if the sensor has drifted beyond an acceptable
limit defined by that user. When drift has occurred or the sensor is new, it is best to perform a 2-point calibration.
Rhodamine WT solution is needed when performing a 2-point calibration. When there isn't an opportunity to prepare
the Rhodamine WT solution, users may choose to at least re-zero the sensor by completing a 1-point calibration.
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