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INFICON HAPSITE ER Chemical Identification System User Manual

Page 382

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HAPSITE ER Operating Manual

Peak Resolution (dx) . . . . . . . . . . . This number indicates the minimum number

of scans between two peaks. It is used to
determine whether a peak should be split into
two or considered only one.

Noise Level Mult. . . . . . . . . . . . . . . A peak intensity must be greater than this

number multiplied by the baseline noise in
order to be called an analyte.

Min. Area . . . . . . . . . . . . . . . . . . . . . This number discriminates against low

responses which are usually attributed to
noise rather than detection of the analyte.
Increase this number to 10,000 or more if
false hits are encountered.

Min. Width . . . . . . . . . . . . . . . . . . . . This number specifies the minimum number

of scans to comprise a peak. This is another
discrimination against low responses or
noise.

Max Width . . . . . . . . . . . . . . . . . . . . This number specifies the maximum number

of scans to comprise a peak. This allows
discrimination against a very broad peak.

Precedence Level. . . . . . . . . . . . . . When compared to the compound-specific

precedence level, it determines which search
parameters to use — the global parameters
specified in

Figure 11-37

or the

compound-specific parameters. As a general
rule, leaving this set to 0 allows one to use
specific search parameters for individual
compounds as discussed in

Chapter 12

.

Min. Fit. . . . . . . . . . . . . . . . . . . . . . . This compares the expected mass intensities

relative to each other to those saved in the
library. Reasonable values depend on the
selectivity of the calibration, but typically 0.5
to 0.9 is used. This value is a way of lowering
false positives, where a higher number is
more discriminative.

Min. Purity. . . . . . . . . . . . . . . . . . . . This measures the purity level of the peak

detected compared to the mass peak in the
library. Reasonable values depend the
selectivity of the calibration, but typically 0.5
to 0.9 is used. This value is a way of lowering
false positives, where a higher number is
more discriminative.