Preparation of new polymeric electrodes for sulfamethoxazole and their use in determining some drugs

     In this study two types of ion-selective electrodes (ISEs) were prepared based on PVC matrix membrane.First, four ion-selective electrodes for sulfamethoxazole (SMZ) which based on sulfamethoxazole
(SMZ) and tungestophosphoric acid (TPA) ion-paircomplexas the electro-active materials were prepared. Second, six ion-selective electrodes for sulfamethoxazole (SMZ) whichbased on sulfamethoxazole
(SMZ) and sodium tetraphenylborate (NaTPB) ion-paircomplex as the electro-active materials were also prepared.In both types of ISEs, som of the selectedplasticizers were used such as; Di-octyl phthalate (DOPh),Tri-butyl phthalate (TBPH), Tri-butyl phosphate (TBP),Nitrobenzene (NB), Acetophenone (AP) and o-Nitrophenyloctylether (o-NPhOE) in PVC matrix.The electrodes parameters, linear range of
concentration,Nernestian slope, limit of detection, response time, life time, working pHrang and selectivity were evaluated. Also the statistical treatments wereapplied for the results that include: relative standard deviation (RSD),relative error (Re.), and confidence limit for concentration. The results showed:The first type ISEs were: SMZ-TPA+DOPH (E1),SMZ-TPA+TBP (E2),SMZ-TPB+AP (E3) andSMZ-TPA+NB (E4), give the linear Range from (1×10-5-1×10-2, 1×10-7-1×10-2, 1×10-5-1×10-21×10-2 M), and the slopes are (52.008, 58.381, 56.909 and 50.309 mV/decade)respectively, with detection limits are (9×10-6 and 1×10, 9×10 and 7×10-6M), response time of 10-3 M (30, 28, 36 and 25 second) and the lifetimewere about (29, 27, 20 and 9 days) respectively.The second type, were: SMZ-NaTPB+TBPH (L1), SMZ-NaTPB +NB
(L2), SMZ-NaTPB +TBP (L3), SMZ-NaTPB +AP (L4),SMZ-NaTPB +DOPH (L5) and  SMZ-NaTPB +o-NPhOE (L6) give the linear range from (1×105-1×10-2-5-1×10 and 1×10-2-5, 1×10-1×10-5-2-1×10-2, 1×10
-5-1×10-2, 1×10-5-1×10M), the slopes are (53.609, 49.608, 56.810,55.709,  50.808  and  51.808 mV/decade)respectively, with detection limits of (9×10-6, 8.5×10-6, 8×10-6,8.9×10-6,  7.5×10-6-2, 1×10-
 and 7×10M),response time of 10-3 M (16, 14, 24, 19, 16 and 20 second) and the lifetime were about (12, 6, 24, 17, 26 and 7 days) respectively.The best electrode from first kind is (E2) and from the second kind is (L3), both were used to determine the sulfamethoxazole in pure samples.The working pH for (E2) electrode was ranged from (1.6-6.8) and the working pH for (L3) electrode was ranged from (1.7-6.9). The interferences measurements in the presence of (NaAl+3+, K+, Cu+2, trimethoprim, starch, sucrose and gelatin ) were studied for both electrodes  using the separated method and mixed method for selectivity coefficient determination