MC Calibration
Overview
UniCel DxC Systems Instructions For Use A13914 Troubleshooting Calibration and Result Errors
October 2005 Page 13-3
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MC Calibration
Overview
The DxC calibrates MC chemistries using two or three calibrator levels. Four
replicates are assayed per calibrator level. Of the four replicates, only the two middle
values are used to set calibration. The highest and lowest values are discarded. The
analog signals generated by the calibrator measurements are converted to digital form
(ADC values). The resulting ADC values are compared to pre programmed error
limits for back-to-back, span, and calibrator range to determine the integrity of the
calibration.
MC Calibration Checks
Both results and interim data are error checked when calibrating a chemistry. Standard
results errors, as well as interim error flags, are applied to the calibration data.
Back-to-Back
• The Back-to-Back error check is a measure of system precision during calibration.
• A back-to-back value is the difference between the two middle Sample-Reference
replicate values within a calibration level. If the back-to-back limit is exceeded the
calibration fails.
• Only the two replicates that meet back-to-back are used; all other replicates are
discarded.
• Select Calibrator Acceptance Limits under Options in the Rgts/Cal screen to view
current calibration limits.
Calibrator Range (High/Low)
• The Calibrator Range (High/Low) error check is a measure of reagent and electrode
performance or accuracy.
• Calibrator ADC values are compared to acceptable ranges for calibrator values.
Calibration fails if the calibrator ADC values fall outside the acceptable calibrator
limits.
• Select Calibrator Acceptance Limits under Options in the Rgts/Cal screen to view
current calibration limits.
DAC
• The DAC error check verifies proper operation of electrodes.
• The Digital-to-Analog Conversion (DAC) check mimics expected ranges of
electrode output. Failure to detect an output within a predetermined range for each
channel will trigger a DAC ERROR flag for the specific electrolyte.
• Limits are as shown in Table 13.2 at the top of the following page:
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