Polymeric nanofilm-coated optical fibre sensor for speciation of aromatic compounds

An optical fibre sensor has been shown to be suitable for monitoring of benzene, toluene and o-xylene (BTX) with both high selectivity and sensitivity. The sensing principle underlying this experimental device is based on the changes of the reflected optical power when BTX vapours are present in the analytical tube containing an optical fibre coated with a thin film of poly[methyl(3, 3, 3-trifluoropropyl)siloxane]. The interaction of organic vapour with the sensitive surface promotes a variation of the light power, proportional to the amount of adsorbed BTX vapour. A set of experiments concerning different operational conditions was performed in order to promote a higher analytical performance and the newly developed BTX sensor showed higher sensitivity and shorter analytical time than a method based on gas chromatography–flame ionisation detector. Furthermore, the proposed sensor also provides the basis for an inexpensive analytical technique with adequate specificity for measurements of BTX at trace levels with appropriate reversibility, repeatability, and reproducibility. Finally, the analytical performance of the developed sensor was also evaluated and found adequate for industrial air samples.