Beckman Coulter UniCel DxC 600, Instructions For Use Manual

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A13914AF
12-4
Troubleshooting Calibration and Result Errors
MC Calibration
Sample/Reference Deviation
•
The Sample and Reference deviation error checks are used as a measure of noise for
electrolytes.
•
Each Sample ADC and each Reference ADC is actually an average of ten readings.
•
The difference between the high and low values (deviation) of the ten electrode readings (taken
milliseconds apart) must be within the maximum deviation.
•
Maximum deviations are as shown in Table 12.3 below:
Span
•
Span is a measure of sensitivity and verifies that two consecutive calibrator level ADC values are
a minimum distance apart.
•
The difference between the average ADC value of Calibrator 1 and the average ADC value of
Calibrator 2 or between the average ADC value of Calibrator 2 and the average ADC value of
Calibrator 3 must exceed the minimum span limit.
•
Select Calibrator Acceptance Limits under Options in the
Rgts/Cal
screen to view current
calibration limits.
Calibration Reports
The Calibration Report can be a useful tool for identifying issues. Table 12.4 below defines the Fields
in the order they are shown for each chemistry on a typical ISE Module Calibration Report.
Table 12.3 Maximum Allowable Sample/Reference Deviations by Chemistry
Chemistry Maximum Deviations
Sample Reference
NA 200 200
K 150 150
CL 200 200
CALC 150 150
Table 12.4 ISE Module Calibration Report Field Definitions
Field Description
Sample Reference The difference between the sample and reference ADC values. This is used
for the back-to-back, range, and span checks.
For CO
2
, the sample reference value is the ratio between the sample and
reference readings.
Sample The average of eight ADC readings of the calibrator sample.
For CO
2
, the sample ADC represents the rate of pH change initiated by the
calibrator sample.