Peak width note

A note about the peak searching field “Estimated peak width as FWHM”

This control was added to the Chrom Fitting tab of TERN with version 2.2.1. The control is highlighted in blue in the figure below. From feedback from various users, it has become clear that the utility of this control was poorly conveyed. We offer a better explanation here.

In simple terms, TERN uses a multi-step flowpath to fit peaks:

1. Peak searching

a. Look for plausible candidate peaks for fitting

b. Identify the best of the candidate peaks for fitting

2. Peak fitting - attempt to fit a Gaussian or exponentially-modified Gaussian function to the candidate peak

Peak searching can struggle without some constraints on the possible peaks. We have found that defining the width of the chrom peak can serve as a powerful guide for improving the likelihood that TERN will identify the correct peak, by reducing the number of possible candidate peaks that TERN must evaluate.

We strongly recommend that the user enter an estimate of the peak width before attempting an automated peak fit run. There is considerable margin in the estimate (approx. +/- 60%) so an exact value is not required. You should not need to adjust this value with peak area.

The default value is 0.0 sec, which is equivalent to turning the control off.