Abstract − Analytical Sciences, 20(2), 285 (2004).
New Highly Selective Picrate Sensors Based on Charge-Transfer Complexes
Mohamed A. F. ELMOSALLAMY
Department of Chemistry, Faculty of Science, Zagazig University, Zagazig, Egypt
Two novel highly selective potentiometric membrane sensors responsive to picrate ion were developed. They are based on the use of N,N′-dibenzoyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (DD18C6)-picrate and Kryptofix 222-picrate charge-transfer complexes as novel electroactive materials in poly(vinyl chloride) matrix membranes plasticized with o-nitrophenyloctylether or dioctylphthalate. The sensors show a Nernstian response with anionic slopes of -59.0 ± 0.1 and -58.0 ± 0.2 mV decade-1 over concentration ranges of 6.0 × 10-5 × 1.0 × 10-2 and 7.0 × 10-5 -1.0 × 10-2 mol l-1 picrate ion and pH ranges of 5 - 11.5 and 5.5 - 11.5 for DD18C6 and Kryptofix 222 based picrate sensors, respectively. Both sensors show highly selectivity towards picrate ion over many hydrophilic and lipophilic anions, and exhibit a non-Hofmeister selectivity sequence, which is an improvement over methods reported so far. The sensors are used for the titrimetric determination of alkaloids using picrate as a titrant.
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