Micellar and analytical implications of a new potentiometric PVC sensor based on neutral ion-pair complexes of dodecylmethylimidazolium bromide–sodium dodecylsulfate

With an aim to characterize the micellar aggregates of imidazolium based ionic liquids, a new potentiometric PVC sensor based on neutral ion-pair complexes of dodecylmethylimidazolium bromide–sodium dodecylsulfate (C12MeIm+DS−) has been developed. The electrode exhibited a linear response for the concentration range of 7.9 × 10−5–9.8 × 10−3 M with a super-Nernstian slope of 92.94 mV/decade, a response time of 5 s and critical micellar concentration (cmc) of 10.09 mM for C12MeImBr. The performance of the electrode in investigating the cmc of C12MeImBr in the presence of two drugs [promazine hydrochloride (PMZ) and promethazine hydrochloride (PMT)] and three triblock copolymers (P123, L64 and F68) has been found to be satisfactory on comparison with conductivity measurements. Various micellar parameters have been evaluated for the binary mixtures of C12MeImBr with drugs and triblock copolymers using Clint’s, Rubingh’s, and Motomura’s approach. Thus the electrode offers a simple, straightforward and relatively fast technique for the characterization of micellar aggregates of C12MeImBr, complementing existing conventional techniques. Further, the analytical importance of proposed C12MeIm+-ISE as end point indicator in potentiometric titrations and for direct determination of cationic surfactants [cetylpyridinium chloride (CPC), tetradecyltrimethylammonium bromide (TTAB), benzalkonium chloride (BC)] in some commercial products was judged by comparing statistically with classical two-phase titration methods.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (73 K)Download as PowerPoint slideHighlights► A new potentiometric sensor for alkyl imidazolium ions has been developed. ► The electrode can be used to study micellar behavior of dodecylmethylimidazolium bromide. ► The sensor served to successfully determine cationic surfactants levels in commercial samples. ► The electrode could also be utilized as an end point indicator in surfactant titrations.