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HPLC Gradient Peaks

Gradient Peak Shapes

In gradient HPLC, the once-generalized chromatographic peak models used for isocratic elutions will not work. The changing strength of the gradient across the time of elution for a peak will change its shape, producing a more compact tailing. In order to effectively fit gradient HPLC peaks, this more compact fourth moment must be addressed in some manner.

Approaches to Fitting Gradient Peaks

This fourth moment compression can be addressed in at least three different approaches:

1. Direct Closed Form Fits of the Gradient Peaks which Include Fitting the Tail Compression as a Fourth Moment Effect
2. Fitting a Deconvolution Model that Estimates and Unwinds the Gradient
3. Unwinding the Gradient and Fitting a Once-Generalized Model with or without an IRF

To better understand these different approaches, you may wish to explore the following tutorials:

1. HPLC Gradient Peaks - Direct Closed Form Fits (Tutorial)
2. HPLC Gradient Peaks - Fits Which Model the Gradient (Tutorial)

3. HPLC Gradient Peaks - Fitting Unwound Data (Tutorial)