Cyclodextrin based potentiometric sensor for determination of ibuprofen in pharmaceuticals and waters

In this work, a potentiometric sensor for ibuprofen monitoring in pharmaceuticals and waters is described. The sensor development relied on comparative performance evaluation of membranes based on several commercial cyclodextrins. The optimum membrane comprised 1.2 wt.% α-cyclodextrin, 65.6 wt.% o-nitrophenyloctylether plasticizer, 42% mol (relative to the molar concentration of the ionophore) of tetradodecylammonium bromide and 32.8 wt.% PVC. A conductive polymeric resin coated with the membrane used as low impedance solid contact completed the sensor device. The sensor presented a constant sensitivity of −59.0 mV dec−1 in the concentration range of 3.87 × 10−6 to 10−2 M, for samples with pH adjusted to 9. The response time was fast <15 s and reproducible (±0.8 mV) with constant performance over more than 6 months. The practical limit of detection was of (3.34 ± 0.03) × 10−6 M ibuprofen. Sample analysis enabling accurate and reproducible results as well as the ability to be coupled to samples front-end conditioning procedures used in environmental analysis is also evidenced.