Emerson Process Management 3-9000-522 Manual Do Utilizador

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.