Quantitative Determination of Duloxetine Hydrochloride in Biological Samples of Blood Serum and Urine Using a Novel Potentiometric Sensor

In this work, a potentiometric sensor was developed based on polyvinyl chloride (PVC), duloxetine tetraphenylborate ion pair, various plasticizers of dioctyl phthalate (DOP), benzyl butyl phthalate (BBP), di(2-ethylhexyl)phthalate (DEPH), tris(2-ethylhexyl) phosphate (TEPH), dibutyl butyl phosphonate (DBBPh), dibutyl phthalate (DBP), dioctyl sebacate (DOS), dibutyl sebacate (DBS), 2-nitrophenyl octyl ether (NPOE) and di-octyl phthalate (DOPH)) and THF as membrane solvent. The electrode responses at various contents of PVC and plasticizer were recorded to optimize their percentage compositions, and the best Nernst response (59.7) was obtained. The linear concentration range for this electrode made by optimal composition is 0.7 µM to 0.1 M with a detection limit of 0.3 µM.  The response time of the ion-selective electrode based on the duloxetine-tetraphenylborate ion pair was determined. The effect of pH on the potential of duloxetine hydrochloride (DHCl) solution with a concentration of 1.0 mM was studied. Moreover, the performance of the prepared electrode was studied over two months to investigate the constructed membrane electrode’s stability. The selectivity coefficients of the electrode for determination of DHCl in the presence of some ions and molecules including Na+, K+, Li+, Ni+, Mg2+, Cd2+, Zn2+, Mn2+, Fe2+, Ca2+, Cu2+, Co2+, Cr2+, ascorbic acid, D-fructose, sucrose, aspartic acid, L-H-histidine, dopamine, glucose, uric acid, propranolol, dexamethasone and melatonin were determined using a separate solution method (SSM) and an adapted potential method. The application of the proposed sensor to determine DHCl in two biological matrices, including blood serum and urine samples, was also investigated.