Analyzing Soy meal in transmitance (part 1)

One of the common applications in NIR analysis is the measure of soy meal, to predict Moisture, Protein, Fat and Fiber. As we know, Protein is the most important parameter and it is important to get an accurate prediction.

What about to measure soy meal in a transmittance instrument like Infratec?. Infratec has a smaller range, but this range (850 to 1050 nm) penetrate most into the sample, so we can measure in transmittance with a certain path length to avoid saturation. With this purpose, a certain number of samples with known reference value for the parameters was analyzed in the instrument, putting the soy meal unground and directly into the conveyor.

Spectra of the samples was export in a spectra file and lab values added.

Spectra file was export into R software as raw spectra, and a multiple scatter correction was added.

X<-as.matrix(sm_ift[,6:105])
wavelengths<-as.matrix(seq(850,1048,by=2))
matplot(wavelengths,t(X),type="l",
        xlab="wavelengths",ylab="transmitance")

#Math Treatments
#Multiple Scatter Correction
library(pls)
X_msc<-msc(X)
matplot(wavelengths,t(X_msc),type="l",
        xlab="wavelengths",ylab="transmitance")

#Mean Centering
  #We can check in wich areas is the variation of the data.
X_msc_mc<-scale(X_msc,scale=FALSE)

#We can see the variation at every wavelength with a boxplot.
boxplot(X_msc)