Using the polynomial baseline correction (FB)
This subroutine calculates a 5th order polynomial fit to the baseline.
(Note that FB is not included in NUTS Lite.)
This is the most practical way to correct a baseline which needs more than simple tilt correction.
Type FB or select Fit Baseline from the Process menu.
On entering the subroutine, NUTS divides the spectrum into 64 regions. Those regions which consist of only noise are colored red.
The decision as to what constitutes noise is based on the RM multiplier value (same parameter as is used for peak picking). Regions can be selected or de-selected by clicking with the left mouse button.
Perform a least squares fit by typing L or by choosing Calculate Fit from the Edit menu.
The calculated polynomial can be drawn by typing P or selecting Draw Polynomial from the Display menu.
If the match to the baseline is not sufficient, try selecting or de-selecting some regions, and repeat the fit.
Exit the routine with <Enter>, which applies the correction.
Exiting the routine with X quits without applying the correction.
See also: QB — Quick polynomial baseline correction. This command performs the same least squares fit to a 5th order polynomial, but no user interaction is possible.
Another option which works well in some cases is a "deduced" baseline.
Last updated: 3/14/04.