Microscale optical fibre sensor for monitoring in landfill leachate

Leachates derived from landfill constitute a serious environmental concern as a variety of pollutants can leak from the landfill sites with potential risk of groundwater pollution. Benzene, toluene, ethylbenzene, p-xylene, m-xylene and o-xylene (BTEX) are pollutants widely found in landfill leachate and therefore the development of analytical methodologies which can provide a rapid and simple measurement of these compounds is of great interest. This paper reports an optical fibre (OF) sensor for environmental applications, namely for BTEX determination in landfill leachate samples.Firstly the analytical signal of the developed OF sensor was evaluated regarding some operational variables affecting the deposition of the sensitive siloxane film (type of siloxane cladding, deposition technique, number of cycles for deposition, cure temperature and experimental conditions for stabilization) in order to achieve a high sensitivity of the analytical system. Secondly, the OF based sensor was applied to landfill leachate samples for detection and quantification of BTEX. The obtained results have been compared to the ones obtained by the method based on a gas chromatography-flame ionization detector (GC-FID).The developed OF methodology showed notable analytical advantages, such as high analytical sensitivity and accuracy, good linearity and stability of the analytical signal, and detection limits in the order of a few nanograms (raging from 0.9 to 1.4 ng) for BTEX determination.