Drug-selective electrode for ketamine determination in pharmaceutical preparations and electrochemical study of drug with BSA.

Ion-selective membrane electrode to the drug ketamine hydrochloride has been constructed using a modified PVC membrane which has ionic end-groups as ion-exchanger sites and which was cast using plasticized with ortho-nitrophenyloctyl ether (o-NPOE) as plastisizer. This drug electrode show excellent Nernstian responses (59 mV per decade) in the concentration range 1 x 10(-5)-1 x 10(-2) M with a detection limit of 5 x 10(-6) M. Response time was about 10 s for ketamine concentrations between 1 x 10(-5) and 1 x 10(-2) M. The response is not affected by pH between 4 and 8.5. Selectivity coefficients against various organic and inorganic cations were evaluated. The electrode was applied for determination of ketamine hydrochloride in pharmaceutical preparations using direct potentiometry. The drug electrode has also been used to study the interaction of bovine serum albumin (BSA) with ketamine in buffer solution (phosphate, pH 7). The saturated quantities of ketamine binding were 114, 32 and 25 mol/mol in 0.01, 0.02 and 0.1% of protein, respectively. The Hill equations were applied to obtain co-operative drug bindings to BSA at 27 degrees C. Copyright 2002 Elsevier Science B.V.