Novel Imidazole PVC‐Based Membrane Sensor Based on 4‐Methyl‐2,6‐diphenylthiopyrylium

ABSTRACT

A novel poly(vinyl chloride) (PVC)‐based membrane sensor based on 4‐methyl‐2,6‐diphenylthiopyrylium perchlorate (MPPP) is presented. The best performance was obtained with a membrane containing 30% PVC, 53% plasticizer dibutyl phthalate (DBP), 7% ionophore MPPP and 10% oleic acid. The proposed membrane electrode responds to imidazole in a wide concentration range 1.0 × 10⁻⁵ to 10 × 10⁻¹ M, with a sub‐Nernstian slope of +36.2 ± 0.2 mV per decade of activity of imidazole. The detection limit of the sensor is 2.0 × 10⁻⁶ M and can be used for at least four weeks without any measurable change in sensitivity. The sensitivity of the electrode is high enough to permit the detection of as little as 0.15 µg/mL of imidazole without any significant interference from high levels of other components such as common cations and anions and specially, amino acids. The potentiometric selectivity coefficient data revealed negligible interference from common cations, inorganic and organic anions, and amino acids. The electrode shows a relatively fast response time in whole concentration range (<30 s). The proposed membrane electrode was used for fast direct potentiometric monitoring of imidazole in synthetic serum samples.

Keywords:

• Potentiometry
• Imidazole
• 4‐Methyl‐2,6‐diphenylthiopyrylium perchlorate
• PVC
• Sensor
• Synthetic serum