Identification by GC-O and GC-MS of new odorous compounds in natural rubber
Résumé
Natural rubber products emit malodourous compounds, which can contaminate the air and water of the inhabited surroundings of the production factories. Analytical methods such as SPME coupled with GC-MS and GC-O-FID were used to elucidate the composition and olfactory impact of volatile compounds released from two various grades of natural rubber submitted to different coagulation processes. Forty-three volatile compounds were identified and amongst 16 of them that had never been reported. The volatile compounds belonged to different chemical classes and were the result of enzymatic and microbial action as well as thermal degradation. Among the new compounds identified, a terpene (limonene), benzyl derivatives, or trimethylamine were found in both grades of natural rubber. In contrary phenyl acids, fatty acid esters, or 2,6 dimethoxyphenol were specific to one grade of natural rubber and may result from the coagulation process. The use of GC-O analysis emphasized the contribution of short-chain fatty acids to the malodorous odour generated but also evidenced the participation of trimethylamine and 2,6 dimethoxyphenol. At last, it was demonstrated that the presence of phenyl acids in one natural rubber could partially mask the obnoxious odour.