Development and Validation of Potentiometric Ion Selective Screen Printed Electrode for Sensitive Determination of Linagliptin in Pure Form and in Pharmaceutical Formulation; Application to Dissolution Testing

A novel screen printed graphite ion-selective electrode (SPE) was prepared and characterized for determination of linagliptin (LNG) in pure form and in pharmaceutical formulation. The electrode is based on LNG-tetraphenyl borate (LNG-TPB) as ion exchanger and tricresyl phosphate (TCP) as a plasticizer. Several parameters such as the type of solvent mediator, amount of the ion-exchanger and working pH range were studied for optimal potentiometric response. Under optimal experimental conditions, the sensor exhibited a Nernstian slope of 60.10±1.02 mV/decade (n=3) over the concentration range from 1.00×10-5 to 1.00×10-2 M (r =0.9999) with LOD of 4.50×10-6 M. The electrode can be used safely over a wide pH range from 4.0 to 8.0. The electrode showed a high selectivity for LNG against common interfering substances. Fast potentiometric response was obtained within 5 seconds and remained stable for at least 60 S. The electrode was applied to the analysis of LNG in pure form and in pharmaceutical dosage form with high accuracy (98.00-102.00%) and precision (%RSD ≤2%). Our electrode has the advantages of being inexpensive, simple, sensitive, portable and disposable.