Savitzky-Golay algorithm

First the signal was smoothed through a Savitzky-Golay algorithm, whose parameters were optimized considering the mean fringe number for a fixed temperature variation. 

The Savitzky-Golay algorithm could readily be adapted for polynomial interpolation. The computations are virtually identical to smoothing. In smoothing, a polynomial is fitted to a range of (x,y)-data pairs arranged around the x-value that needs to be smoothed. For polynomial smoothing, the polynomial is evaluated for a set number of data points around the desired x-value and the computed y-value at that x is the interpolated value. 

The use of Savitzky-Golay algorithm requires optimalisation such parameters as derivative order, polynomial degree, width of derivatisation window and manner how derivative is generated. Analytical usefulness of resulted derivative spectrum depends on proper selection of mentioned parameters. Their selection should be done by taking into accoimt a shape of initial zero-order spectrum and spectral properties of accompanied compounds. 

Derivative spectra of higher orders can be obtained using Savitzky-Golay algorithm in two ways by direct generation of desired derivative sp>ectrum or by gradual generation of first... 

In OPUS the Savitzky—Golay algorithm [1—3] is applied to smooth a spectrum. Possible values for smoothing points are 5 to 25. Open the smooth dialog box shown in Fig. 10.26, select the spectrum as usual, choose the number of smoothing points and click on the Smooth button to start the function. 

The Second Derivative method is typically applied in order to be independent of the baseline. As in the case of the Derivative function (see Section 10.11) the Savitzky-Golay algorithm is actually used to obtain the derivative. Again, the number of smoothing points used can be adjusted to suppress the effect of... 

Processing the previously acquired data by subjection to a mathematical treatment such as curve smoothing (e.g. with the Savitzky—Golay algorithm), derivation, calibration or spectral refining. Data can be also exported to be processed with other software (e.g. Excel spreadsheet). 

To minimize the effects of baseline variations due to Mie scattering, the ANN analysis was performed on second derivative spectra derived from the raw spectra processed using a Savitzky-Golay algorithm (nine points). 

Fourier differentiation is another method that is used less often but has the advantage of higher computational speed than the Savitzky-Golay algorithm and greater accuracy than the gap-and-segment method. In this approach the Fourier transform of an absorbance spectrum is multiplied by a function of the form ax". 

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