A new method for the simultaneous determination of vulcanized rubber additives by Fourier transform infrared (FT-IR) spectrophotometry using partial least-squares regression (PLSR) for multivariate calibration was developed. The effect of various wavenumber ranges and the use of the absorbance and first-derivative spectral modes on performance were studied by applying the method to three different sample batches containing several additives in different proportions, all of which were resolved with satisfactory results.
M. Blanco, J. Coello, H. Iturriaga, S. Maspoch, and E. Bertran, "Simultaneous Determination of Rubber Additives by FT-IR Spectrophotometry with Multivariate Calibration," Appl. Spectrosc. 49, 747-753 (1995)