For the generation of calibration plot for TPC, the region of
1060–550 cm1 provided the satisfactory regression results. The
region was selected by TQ software to obtain good regression.
The region of FTIR spectrum from 1060 to 550 cm1 behaved very
well for all calibration models intended for TPC, CV, CD and CT
determination.
Application of PLS chemometrics technique on a wide range of
TPC standards from 2.10% to 26.80% is shown in Fig. 2a.
Reasonable values were obtained from calibration model of TPC
for R2 (0.999), RMSEC (0.193), RMSEP (0.809) and RMSECV (1.828).