30 mar. 2012

Comparing Spectra with different math treatments

It is amazing the quantity of graphics you can develop with R, and how you can show and manage  these graphics. Here in the same plot we compare the raw demo spectra, treated with MSC, SNV and with the first derivative (differences between consecutive  data points). We can see how SNV and MSC look similar, but if you look to the Y  axis, they are different.
In the first derivative spectra there is a big peak of noise at 1100 nm. At this wavelength the detector change from “Si” to “PbSn”, so the difference in absorbance’s is quite high (from 1098 to 1100), so we have to exclude this area if we develop the calibration with the full spectrum range.

Using: par(mfrow=c(2,2)) opens a window, where we plot our spectra with the four different treatments.

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