Ultrasensitive Chemically Modified Carbon Paste Sensor for Reliable and Selective Potentiometric Determination of Trace Amounts of Sitagliptin in Real Samples

Abstract

A new chemically modified potentiometric carbon paste electrode was fabricated based on incorporation of the ion association complex of sitagliptin‐phosphotungstate to determine sitagliptin. The proposed sensor displayed a Nernstian slope of 59.4 mV/decade for sitagliptin over a concentration range of 1.7×10−8 to 2.2×10−5 M and a detection limit of 9.1×10−9 M. It represented the advantages of fast response, long lifetime and, most importantly, excellent selectivity for sitagliptin versus a wide variety of usual inorganic cations and also biological species such as amino acids and sugars. The temperature dependence of sensor potential was examined, and it was figured out that the sensor has a low thermal coefficient in the temperature range of 15–55 °C. The sensor was applied to determine sitagliptin in pharmaceutical tablets, milk and blood serum samples. The obtained suitable recoveries and relative standard deviations confirmed that the developed sensor could be precisely applied to determine sitagliptin in real samples.