Potentiometric response of modified carbon paste electrode based on mixed ion-exchangers

A new chemically modified carbon paste electrode based on a mixture of two ion-exchangers namely chlorpheniramine-silicotungstate (CPM-ST) and chlorpheniramine-tetraphenylborate (CPM-TPB) as ion-exchange site for determination of chlorpheniramine maleate (CPM) was described. The best performance was exhibited by the electrode having the paste containing 3.0 wt% ion-exchangers (CPM-ST&CPM-TPB), 48.5 wt% graphite, 47.5 wt% DOPh and 1.0 wt% NaTPB. The proposed chemically modified carbon paste electrode exhibited a Nernstian response for CPM over a wide concentration range of 1.2 x 10(-6) to 1.0 X 10(-2) M with a detection limit of 5.1 X 10(-7) M between pH 4.5 and 7.7 with fast response <= 10 s. The sensor showed good selectivity for CPM with respect to a large number of inorganic cations, organic cations, sugars, amino acids and some common drug excipients. The modified electrode was applied to potentiometric determination of CPM in its pharmaceutical preparations and biological fluids (serum and urine) with average recoveries of 97.5-102% and relative standard deviations of 0.32-1.97%.