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Indomethacin ion-selective electrode based on a bis(triphenylphosphoranylidene)ammonium-indomethacin complex

R Aubeck1, C Bräuchle, N Hampp

  • 1Institute of Physical Chemistry, Ludwig-Maximilians-Universität, München, Germany.

The Analyst
|August 1, 1991
PubMed

Insights

This study details a new ion-selective electrode for detecting indomethacin, achieving a low detection limit and a wide linear range. The electrode demonstrates excellent selectivity against various organic and inorganic ions.

Area of Science:

  • Analytical Chemistry
  • Electrochemistry
  • Materials Science

Background:

  • Ion-selective electrodes (ISEs) are crucial for quantifying specific ions in complex matrices.
  • Developing sensitive and selective electrodes for pharmaceuticals like indomethacin is essential for therapeutic drug monitoring and quality control.
  • Poly(vinyl chloride) (PVC) membranes offer a versatile platform for constructing ISEs due to their processability and compatibility with various ionophores.

Purpose of the Study:

  • To describe the properties of a novel ion-selective electrode designed for the determination of indomethacin.
  • To evaluate the electrode's performance characteristics, including detection limit, linear range, and selectivity.
  • To assess the interference from various organic and inorganic anions and cations.

Main Methods:

  • Fabrication of a PVC membrane incorporating a bis(triphenylphosphoranylidene)ammonium-indomethacin ion-pair complex as the ionophore.
  • Electrochemical characterization of the electrode using potentiometric measurements.
  • Determination of the electrode's response to indomethacin at pH 7.0.
  • Evaluation of selectivity coefficients against various organic and inorganic anions and cations.

Main Results:

  • The developed ion-selective electrode exhibited a detection limit of 2 x 10(-5) mol L(-1) for indomethacin at pH 7.0.
  • A linear response range was observed between 5 x 10(-5) and greater than or equal to 10(-3) mol L(-1).
  • The electrode showed high selectivity for indomethacin over common organic anions (naproxenate, salicylate, tartrate) and negligible interference from cationic species. Strong responses were noted for inorganic anions like perchlorate (ClO4-), with detection limits as low as 6 x 10(-7) mol L(-1).

Conclusions:

  • The bis(triphenylphosphoranylidene)ammonium-indomethacin ion-pair complex in a PVC membrane forms an effective ion-selective electrode for indomethacin.
  • The electrode offers good sensitivity, a wide linear range, and excellent selectivity, making it suitable for indomethacin determination.
  • The electrode's selectivity profile for inorganic anions aligns with the Hofmeister series, suggesting potential for broader anion sensing applications.

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