A large panel of Natural Rubber (NR) samples was characterized using Fourier Transform
Infrared (FT-IR) spectroscopy in Attenuated Total Reflection (ATR) configuration. Specific
vibrational bands were attributed to some non-isoprene compounds naturally present in
NR composition. A rapid and non-destructive method was developed to investigate some
specific functional groups contained in lipids (ester and carboxyl groups) and proteins
(amides). Ester and carboxyl groups were quantified using calibration curves developed
from synthetic cis-1,4-polyisoprene mixtures with either methyl stearate or stearic acid.
Amide groups of proteins and peptides were found to be directly quantifiable from NR FTIR
spectra. The clonal origin and processing were found to influence the non-isoprene
composition of NR. Significant correlations were found between FT-IR results and conventional
chemical analyses: nitrogen content for proteins and total lipid extract.