C-2 DATA COMPUTATIONS
MON2000
Peak Detection JULY 2010
where PW is given in seconds. All the various
details in the analysis process are independent
of the value of N. Allowable values of N are one
to 63 which corresponds to values of PW from 2
to 63 seconds.
The variable N is known as the integration
factor. This term is used because N determines
how many points are averaged or integrated to
form a single value. The integration of data
upon input before storing serves two purposes.
First, the statistical noise on the input signal is
reduced by the square root of N. In the case of
N = 4, a noise reduction of two would be
realized. Secondly, the integration factor
controls the bandwidth of the chromatograph
signal. It is necessary to match the bandwidth
of the input signal to that of the analysis
algorithms in the 2350A. This prevents small,
short duration perturbations from being
recognized as true peaks by the program. It is
therefore important to choose a Peak Width
corresponding to the narrowest peak in a group
under consideration.
C.2 PEAK DETECTION
For normal area or peak height concentration
evaluation, the determination of a peak's start,
peak point, and end is automatic. The manual
determination of start and end points is used
only for area calculations in the Forced
Integration mode. Automatic determination of
peak onset or start is initiated whenever
Integrate Inhibit is turned off. Analysis is
started in a region of signal quiescence and
stability such that the signal level and activity
can be considered as baseline values. It is
important that this be the case because the
assumption is made by the 2350A software.
