INFICON Explorer Portable Gas Chromatograph - Manual (Page 230)

Calibration
228
Figure 13 Linear Calibration Curve
Quadratic and Cubic Calibration Curve
A quadratic calibration curve fits a quadratic function to the points you have stored.
In order to use the quadratic calibration curve, you must store at least 2 or more
points. The curve will always start at (0, 0) and go through all the points you have
stored. In order to obtain the most accurate results you should store a point that is at
the top end of the concentration range at which you are looking. If you are interested
in the range 10 to 100 ppm, store a point at 100 ppm. Data past this point will be
extrapolated based on a tangent through the last stored point.
A cubic calibration curve fits a third order function to the points you have stored.
You must store at least three points in order to use a cubic calibration curve. As with
the quadratic curve, you should store a point at the top end of your concentration
range.