Determination of Quinine with Phosphotungstic Acid Modified Ion Sensitive Field Effect Transistor Sensor

We developed a new drug field effect transistor (drug-FET) sensor to detect the quinine concentration in medicinal solution. A drug sensitive membrane, prepared by adding electric active matter into a poly vinyl choride solution, and an ion sensitive field effect transistor were used to compose this sensor. The pH influence, selectivity and response curve of this sensor were investigated. The experimental results indicated that the sensor showed a Nernst response to quinine with a slope of 58.2 mV/decade over the concentration range of 1.0×10^-2-3.2×10^-5 mol/L and the pH range of 3.0-6.0. Within the detection limit about 1.0×10^-6 mol/L, the performance of this sensor was very stable. The obtained results agreed well with the pharmacopoeia method. A preliminary application of the sensor was discussed as well.