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- Title
Molecular iodine selective membrane for iodate determination in salt samples: chemical amplification and preconcentration.
- Authors
Bhagat, P. R.; Pandey, A. K.; Acharya, R.; Natarajan, V.; Rajurkar, N. S.; Reddy, A. V. R.
- Abstract
A molecular iodine selective membrane has been used for preconcentration of I2 generated in situ by iodometric reaction of $${\text{IO}}_{\text{3}}^ - $$ with excess I− in acidic medium (pH 1–2). This iodometric reaction amplifies the iodine content six times resulting in enhancement of analytical response ranging from three times for molecular methods to six times for elemental methods. The chemical conditions of this iodometric reaction were optimized for quantitative generation and subsequent sorption of I2 in the membrane samples (96 ± 3%). The homogeneous transparent membrane was prepared by immobilizing I2-complexing polyvinylpyrrolidone (PVP) in the plasticized cellulose triacetate matrix. Four different analytical methods were examined for quantitative determination of $${\text{IO}}_{\text{3}}^ - $$ in iodized salt samples by preconcentrating it as I2 in the membrane matrix. These methods were: (1) spectrophotometry of the PVP-I2 complex formed in the membrane matrix, (2) a radiotracer method using I− tagged with 131I radiotracer, (3) instrumental neutron activation analysis (INAA), and (4) energy-dispersive X-ray fluorescence (EDXRF) analysis. The $${\text{IO}}_{\text{3}}^ - $$ contents thus determined in the iodized salt samples by the membrane-based radiotracer method were compared with the total iodine determined in salt samples by epithermal instrumental neutron activation analysis (EINAA). The membrane-based method for iodate determination in salt samples has advantages over conventional analytical methods, for example preconcentration and chemical amplification, and is free from interference from anions. [Figure not available: see fulltext.]
- Subjects
CHEMICAL reactions; IODATES; IODINE; NUCLEAR activation analysis; SPECTROPHOTOMETRY; RADIOACTIVE tracers; X-ray spectroscopy
- Publication
Analytical & Bioanalytical Chemistry, 2008, Vol 391, Issue 3, p1081
- ISSN
1618-2642
- Publication type
Article
- DOI
10.1007/s00216-008-2057-1