QUANTITATIVE-ANALYSIS OF ZOPICLONE IN TABLETS USING ION-SELECTIVE ELECTRODE AND POLAROGRAPHIC METHODS

Different types of PVC-matrix ion-selective electrodes (ISEs) that res pond to the cationic form of zopiclone are described. Four ion-pairing agents, namely tetraphenylborate (TPB), reineckate (RN), phosphotungs tate (PT) and silicotungstate (ST), and different plasticizers are inv estigated. The best PVC polymeric membrane contains nitrophenyloctylet her (NPOE) as plasticizer and zopiclone-TPB as active material. This e lectrode exhibits a Nernstian response (60 mV per decade) in the range 1 x 10(-2) to 1 x 10(-5) M and a fast dynamic response time, this res ponse being not affected by pH between 1.9 and 5.5. Direct potentiomet ry was used to determine zopiclone in drug formulations using this new zopiclone-selective electrode. The results are comparable to those ob tained by differential pulse (DP)and square-wave (SW) polarographic te chniques using both direct and standard addition methods.