Using N-aminoperylene-3,4 : 9,10-tetracarboxylbisimide as a fluorogenic reactand in the optical sensing of aqueous propionaldehyde

Aldehydes are usually determined via chemical derivatization using a chromo genic and fluorogenic reagent followed by chromatographic separation and W- visible detection. As a consequence, continuous on-line monitoring is impos sible, Following our concept of reversible chemical reactions as the basis of optical sensors, we have investigated N-amino-N'-(1-hexylheptyl)perylene -3,4:9,-10-tehracarboxylbisimide for aldehyde sensing. The fluorogenic reac tand has been embedded in plasticized PVC, and the resulting thin layers ha ve been exposed to aqueous samples of aliphatic aldehydes and ketones. The reactand exhibits a pronounced increase in fluorescence upon interaction wi th aldehydes since the chemical reaction causes a dequenching of perylene f luorescence, Upon interaction with aqueous propionaldehyde, sensor layers t ypically exhibit a dynamic range from 5 to 100 mM propionaldehyde, and the limit of detection amounts to 0.08 mM, The forward and reverse response tim e (tss) for a decade change in activity is in the range of 2-7 min, when me asured at pH 2.5. The selectivity of sensor layers toward aldehydes correla tes with their Lipophilicity in that aldehydes with higher lipophilicity ar e more efficiently extracted into the polymer layer.