a T: number of PLS terms utilised in the calibration equation.
b R2: coefficient of determination of calibration.
c RMSEC: root mean square error of calibration.
d RMSECV: root mean square error of cross-validation.
e RPD: ratio performance deviation calculated as SD/RMSECV.
f MSC: multiplicative scatter correction.
g 1D: first-order derivative.
h 2D: second-order derivative.