Nanofibers as optical sensors for model VOCs dispersed in aqueous phase

Nanofibers mats, prepared from poly(vinyl chloride) (PVC) containing dispersed dye Nile red (NR) were applied in a proof of concept study as optical sensors for Volatile Organic Compounds (VOCs) dispersed in an aqueous phase. Benefiting from the solubility of the dye, and in some cases, also of the polymer in model solvents belonging to the group of VOCs, an increase of emission was observed for increasing solvent concentration in the sample. The optical signal formation was observed regardless if only the dye or both dye and PVC were soluble in the tested solvent. In both cases, high sensitivity emission increases for increasing VOCs present in the aqueous phase were observed within the range of concentration of model analytes: from 200 ppm of m-xylene or from 300 ppm of styrene, to up to ca 1500 ppm. The obtained higher detection limit was lower compared to films of PVC containing the dye due to the lower availability of the material to be dissolved by analyte – solvent. The large surface area of nanofibers was useful in the detection, leading to higher signal changes compared to films.