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Development of a Novel Automatic Potentiometric System for Determination of Selenium and Its Application in Pharmaceutical Formulations and Anodic Slime
Author(s) -
Kamel Ayman H.,
Elnaby Eman H.,
Kelany Ali E.
Publication year - 2008
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200704138
Subject(s) - potentiometric titration , membrane , chemistry , selenium , detection limit , polyvinyl chloride , plasticizer , solvent , potentiometric sensor , selectivity , inorganic chemistry , flow injection analysis , analytical chemistry (journal) , ion , chromatography , organic chemistry , biochemistry , catalysis
Poly(vinyl chloride) polymeric membrane sensors containing Sn(IV) phthalocyanine dichloride (SnPC) and Co(II) phthalocyanine (CoPC) as novel electroactive materials dispersed in o ‐nitrophenyl octylether ( o ‐NPOE) as a plasticizer are examined potentiometrically with respect to their response toward selenite (SeO 3 2− ) ions. Fast Nernstian response for SeO 3 2− ions over the concentration ranges 7.0×10 −6 –1.0×10 −3 and 8.0×10 −6 –1.0×10 −3 mol L −l at pH 3.5–8.5 with lower detection limit of 5.0×10 −6 and 8.0×10 −6 mol L −1 and calibration slopes of −25.4 and −29.7 mV decade −1 are obtained with SnPC and CoPC based membrane sensors, respectively. The proposed sensors reveals by the modified separate solution method (MSSM) a good selectivity over different anions which differ significantly from the classical Hofmeister series. A segmented sandwich membrane method is used to determine complex formation constants of the ionophores in situe in the solvent polymeric sensing membranes. Membrane incorporating CoPC in a tubular flow detector is used in a two channels flow injection set up for continuous monitoring of selenite at a frequency of ca. 50 samples h −1 . Direct determination of selenium in pharmaceutical formulations and anodic slime gives results in good agreement with data obtained using standard ICP method.