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GE Analytical Instruments ©2016 108 of 270 DLM 68100-09 EN Rev. A
Chapter 5: Calibration and Verification
Figure 31: Calibration Curve for Single-Point Calibration
The concentration of samples is calculated from a calibration equation of the form:
C = b*R
where,
R = Mass Response, μ g
b = Calibration constant (slope)
C = mg/L Carbon, ppm
In a single-point calibration, the calibration constant is the slope of the line shown in Figure 31 , and the response
of the Analyzer is assumed to pass through the origin.
Certain recommendations can be made about the use of single-point calibrations:
• Reagent water (TOC or IC concentration of zero) may not be used as the single point.
• If the highest accuracy is sought, calibrate using at least two points.
• The concentration of the calibration point in a single-point calibration should be greater than the
expected concentration of the samples, but not exceed them by too much.
• Because Auto Dilution contributes some uncertainty to the calibration, single-point calibrations using
Auto Dilution normally are not recommended.
• If you plan to use the Auto Range feature, calibration of the 50,000 ppm range is important because the
preliminary measurement used to determine the appropriate analysis range is performed in this range.
For best performance of the Auto Range feature, it is recommended that the 50,000 ppm range be
calibrated using a six-point, point-to-point calibration (see
page 112 ). The recommended points are:
Reagent Water, 100 ppm, 1,000 ppm, 5,000 ppm, 20,000 ppm and 50,000 ppm.