Chapter 3 Peak Detection and Labeling

• For spectral data, determines the peak boundaries by

 

one of two means:

 

• If the Noise Threshold is greater than zero, the

 

software scans from the valley regions toward the

 

apex region using the number of data points

 

defined by the Filter Width. If the difference

 

between two consecutive filtered regions is

 

greater than the Noise Threshold, the midpoint of

 

the filter region closest to the apex is used as the

 

peak bound.

 

• If the Noise Threshold is zero, the software scans

 

the valley regions for the minimum points to

 

determine the peak bounds.

 

For chromatogram data, determines the peak boundaries

 

by:

3

• Determining the Noise Threshold by performing an

automatic signal-to-noise calculation on the tallest

 

peak in the chromatogram and using 75 percent of

 

the noise value determined as the threshold.

 

• Scanning from the valley regions toward the apex

 

 

region using the number of data points defined by

 

the Filter Width. If the difference between two

 

consecutive filtered regions is greater than the

 

Noise Threshold, the midpoint of the filter region

 

closest to the apex is used as the peak bound.

 

• Compares the area of the new peak to the %Max Peak

 

Area and the Minimum Area. A Minimum Area of 2 is

 

used for chromatogram data. If the new peak is within the

 

specified area settings, the peak is added to the peak list.

3-68 Applied Biosystems