Effect of using mixed ion-pairs on PVC-membrane electrodes for ephedrine |
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Authors: | Mohsen M Zareh |
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Institution: | (1) Department of Chemistry, Faculty of Science, Zagazig University, Zagazig, Egypt |
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Abstract: | Mixed ion-pairs based on the use of ephedrinium (EPH)-TPB plus EPH-reineckate (II) and phenylephrine-TPB plus EPH-reineckate (III) were tried for use in plastic membranes. The results were compared to those of an EPH-reineckate (I) single ion-pair electrode. The Nernstian slopes were 50, 49 and 55 mV decade–1 for membranes I, II and III, respectively. The linear concentration ranges were 10–5–10–1, 4.0 × 10–5–10–1 and 6.3 ×–5–10–1
M ephedrine. The detection limits were 4 ×–6,10–5 and 1.2 × 10–5
M ephedrine for membranes I, II and III, respectively. The pH ranges were 4–9, 3–9 and 2–8 for I, II and III-membranes, respectively. Selectivity coefficient values for membrane II were better than those for membranes I and III. The effects of increasing KC1 concentration and temperature changes were explained for the three electrodes. The isothermal temperature coefficients were 0.00145, 0.0007 and 0.00055 V/ °C for electrodes I, II and III. Electrode III was applied for the determination of ephedrine in its pharmeaceutical preparations with an overall relative standard deviation range of 1.3–2.4% and an overall mean recovery value of 98.1%. |
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Keywords: | mixed ion-pair membranes PVC membrane ephedrine ion-selective electrode |
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