Emerson Process Management 3-9000-745 manual Analysis computations

MON20/20 Software for Gas Chromatographs	User Manual
OCTOBER 2010	3-9000-745

The zero reference line will, in general, be non-horizontal, and thus compensates for any linear drift in the system from the time the peak sequence starts until it ends.

In a single peak situation, peak area is the area of the component peak between the curve and the zero reference line. The peak height is the distance from the zero reference line to the maximum point on the component curve. The value and location of the maximum point is determined from quadratic interpolation through the three highest points at the peak of the discrete valued curve stored in the controller assembly.

For fused peak sequences, this interpolation technique is used both for peaks, as well as, valleys (minimum points). In the latter case, lines are dropped from the interpolated valley points to the zero reference line to partition the fused peak areas into individual peaks.

The use of quadratic interpolation improves both area and height calculation accuracy and eliminates the effects of variations in the integration factor on these calculations.

For calibration, the controller assembly may average several analyses of the calibration stream.

B.3 Analysis computations

There are two basic analysis algorithms included in the GC:

•Area Analysis – calculates area under component peak

•Peak Height Analysis – measures height of component peak

B-3