Ion selective carbon paste electrodes based on ion pair formation for determination of Tetra-n-butyl ammonium bromide

In this study, ion pairs formed between tetrabutyl ammonium bromide as surfactant and ion pairing agents as phosphotungetic acid (PTA), phosphomolybdic acid (PMA) and sodium tetraphenyl borate (NaTPB) have been used as electroactive materials for preparation of modified carbon paste electrodes (CPEs) selective to tetra-n-butyl ammonium bromide (TBAB) surfactant. Type and content of the different ion pairs on the performance of CPEs were studied. It was found that the best contents were, 15 mg of TBA-TPB (electrode I), 15 mg TBA-PTA (electrode II) and 6 mg TBA-PMA (electrode III) ion pairs, which gave the best Nernstian slope values of 59.41±0.31, 59.26±0.45 and 59.95±0.35 mVdecade-1, respectively. These fabricated electrodes exhibited suitable response to TBAB in a concentration range from 1.0x10−6 to 1.0x10-2 mol L-1 with lower detection limit of 1.0x10-6 mol L-1. These fabricated electrodes exhibited fast response time of about 3, 7 and 6 s under working pH range of 3-8, 5-8 and 5-9 for electrodes I, II and III, respectively. The results obtained were satisfactory with excellent percentage recovery comparable and sometimes better than those obtained by other routine methods for the assay of TBAB surfactant.