INFICON Explorer Portable Gas Chromatograph - Manual (Page 228)

Calibration
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Multiple Point Calibration Curve
NOTE: Changes made to the library using Explorer directly, cannot be saved to disk. The
changes will be lost when a new method is loaded.
Multiple point calibration may be used to improve the accuracy of
Explorer’s response over a wide concentration range.
Within a library, each compound may be stored at up to 5 different concentration
points. The first point is always (0, 0), and you can store 4 additional concentration
points. You can also select one of four calibration curves; line segment, linear fit,
quadratic fit or cubic fit.
When you perform a calibration, the calibration curve is updated based on the single
concentration point contained in the calibration gas.
Line Segment Calibration Curve
If one concentration point is stored, Explorer draws a line from this (0, 0) to the
single point and uses the line as the calibration curve. If the compound is stored at
a second, higher concentration, sample concentrations are calculated using the first
sensitivity when the concentration is below the lower concentration. For
concentrations above the lower value,
Explorer uses a sensitivity value calculated
from the slope of the line connecting the two concentration response points.