A simple membrane with the electroactive [Sulfapyridine-H]⁺[Co(C<inf>2</inf>B<inf>9</inf>H<inf>11</inf>)<inf>2</inf>]^- for the easy potentiometric detection of sulfonamides

© 2019 The detection of a drug belonging to the Sulfonamide class of compounds, namely Sulfapyridine, is reported in this work using an in-situ and fast potentiometric method. The strategy employed for this detection is based on the novel ion pair complex, [Sulfapyridine-H]+[Co(C2B9H11)2]- acting as the active site for highly selective recognition of Sulfapyridine. This enables the sensor's selectivity to be improved by incorporating the target molecule to the selective membrane. In this work, all solid state Sulfapyridine selective microelectrodes based on PVC-type membranes were prepared using three different plasticizers and the aforementioned ion pair complex. The sensors developed have provided quick and accurate response within the range of 10−6 mol/dm3 to 10−3 mol/dm3 of Sulfapyridine concentration and showed a Nernstian slope between 47 and 61 depending upon the type of plasticizer used. The lowest limit of detection achieved was 4 μmol/dm3. The potentiometric coefficient of selectivity, KA,Bpot, has shown that the Sulfapyridine-selective microsensors were highly selective towards Sulfapyridine even when compared to other members of the Sulfonamides class of compounds. In addition, from the Reilley diagram it can be observed that the sensor signal is stable for a working pH interval between 6.00 and 8.00.