16 oct. 2014

SG 2nd Derivative + MSC

As you know derivatives remove the baseline offset and curvature in the spectra, but the should be combined with anti-scatter math treatments if we want to remove scatter effects which affect the correlation between the constituents of interest and the spectral bands. There are some cases (especially when developing discriminant models), where it is not convenient to apply the anti-scatter math treatments and we just leave the derivatives alone.
Following the Shoot-out tutorial and following the paper "Shoot-out 2002: transfer of calibration for content of active in a pharmaceutical tablet", from David W. Hopkins (NIR news Vol14 No. 5 2003), I tried the math treatment recommended by the author and apply the MSC after the SG2D1104, just to have a look to the spectra:


You can see how the red spectra, has been calculated in the previous post, and for the green one (SG second derivative combined with MSC), I use the following script:
> X1_sg2dmsc<-msc(X1_sg2d_pracma)
> matplot(wavelength2[11:281],t(X1_sg2dmsc[,11:281]),type="l",

+ xlab="Wavelength (nm)",ylab="1/R (SG 2nd der + MSC)",lty=1,
+ col=3,main="SG-2D1104 + MSC")
If we want to see them over-plotted




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