Novel PVC-free All-solid-state Ion-selective Electrode for Determination of Chlorhexidine in Pharmaceutical Formulations

The potentiometric response characteristics and analytical applications of a poly(vinyl chloride) (pvc)-free all-solid-state ion-selective electrode for chlorhexidine (chx) are examined and compared to those of pvc-based solid-state electrode. the pvc-free electrode is prepared by direct incorporation of chlorhexidine-tetraphenyl borate (chx-tpb) as a sensing element into a commercial nail varnish (nv) containing cellulose acetate propionate. the composite was applied onto a 3 mm diameter graphite disk-electrode. the electrode exhibited a nernestian slope of 29 mv/decade in the concentration range from 10-5 to ?10-3 mol/l with a detection limit of 4×10-6 mol/l. the electrode is independent of ph in the range from 3.6 to 7.9. cationic inorganic ions showed negligible interference, whereas, a strong electrode response was observed for cetrimide and benzalkonium chloride with selectivity coefficients of 8.62 and 7.59 respectively. comparable ph working range and selectivity pattern were observed with the pvc-based electrode. the electrode was used for determination of chx in mouthwash and gargle, without extraction, with high precision (%rsd?2) and accuracy (±2%). the new electrode is simple, economical and rapid when compared to the pvc-based electrode