A novel pH sensing membrane based on an ionic liquid-polymer composite
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- Ping, J., Wang, Y., Wu, J. et al. Microchim Acta (2012) 176: 229. doi:10.1007/s00604-011-0723-z
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A novel pH sensing membrane was developed that consists of the ionic liquid n-cetylpyridinium hexafluorophosphate (CPFP), poly(vinyl chloride), and quinhydrone. The membrane is stable and flexible and can be easily deposited on the electrode. Electrochemical impedance spectroscopy was used to study the interfacial charge transfer of this membrane. Compared to a traditional plasticizer-based membrane electrode, the new electrode possesses excellent potentiometric characteristics for monitoring pH, such as a response time of less than 10 s, high sensitivity, stability, and reproducibility. The response is almost Nernstian, with a slope of −57.5 ± 0.2 mV pH−1 in the pH range from 2 to 9.5. The new electrode was used for direct monitoring of pH in real food samples.