Ionics Instruments 2004 Page 9-17 DLM 30007-08 Rev. A
7. Calculate the % difference between the average TC values and the average IC
values for the IC standard via the calculation given below. Record the value
on the Calibration Worksheet.
% difference = 100*(Average TC - Average IC) / Average TC
The accuracy of the analyzer is ±3% for TC; the TOC (TC-IC) on an IC
standard should be –750 ppb to + 750 ppb based on a 25ppm solution. Per
the above equation, if the percentage difference between the average TC and
IC values is within ±3% of the TC value, the IC channel is properly calibrated,
and there is no need to change the calibration constant. If the percentage
difference is not within ±3%, determine the new IC channel constant as
described below.
WARNING
If the TC channel has just been recalibrated, and there is a large difference
(>10%) between the TC and IC values, it is possible that the TC channel
calibration is incorrect due to incomplete oxidation of the TC/TOC standard.
Repeat the TC calibration procedure using a new TC/TOC standard and a
higher oxidizer flow rate before changing the IC calibration.
NOTE
Save the site-prepared IC standard or use another Ionics Instruments-prepared
vial for rechecking the calibration.
Step 3 – Enter the new IC Calibration Constant:
After the average TC and IC values have been recorded:
1. Press CLEAR to return to the MAIN menu.
2. Scroll to CALIBRATE.
3. Press ENTER to display the CALIBRATION menu.
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