Flow Injection Spectrophotometric Catalytic Determination of Iodine in Milk

Flow Injection Spectrophotometric Catalytic Determination of Iodine in Milk

A flow injection method based on the catalytic action of iodide on the color-fading reaction of the FeSCN2+ complex was proposed and applied to the determination of iodine in milk. At pH 5.0, temperature 32°C and measurements at 460 nm, the decrease in absorbancy of Fe3+-SCN (0.10 and 0.0020 mol l-1...

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Bibliographic Details
Published in:Analytical Sciences Vol. 14; no. 3; pp. 559 - 564
Main Authors: Ana Rita de Araujo NOGUEIRA, MOCKIUTI, Fabiana, SOUZA, Gilberto Batista de, PRIMAVESI, Odo
Format: Journal Article
Language:English
Published: Tokyo The Japan Society for Analytical Chemistry 01-06-1998
Japan Society for Analytical Chemistry
Japan Science and Technology Agency
Subjects:
Biological and medical sciences
Food industries
Fundamental and applied biological sciences. Psychology
Milk and cheese industries. Ice creams
Performance evaluation
Analysis method
Iron III Complexes
Quality control
Thiocyanates
Spectrophotometry
Quantitative analysis
Chemical contamination
Flow injection
Iodine
Milk
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Summary:A flow injection method based on the catalytic action of iodide on the color-fading reaction of the FeSCN2+ complex was proposed and applied to the determination of iodine in milk. At pH 5.0, temperature 32°C and measurements at 460 nm, the decrease in absorbancy of Fe3+-SCN (0.10 and 0.0020 mol l-1) in the presence of NO2- (0.3 mol l-1) is proportional to the concentration of iodide, with linear response up to 100.0 μg I- l-1. The detection limit was determined as 0.99 μg I- l-1 (3σ blank/slope); and the system handles 48 samples h-1. Organic matter was destroyed by a dry procedure carried out under alkaline conditions. Alternatively, the use of a Schöninger combustion after the milk dehydration was evaluated. The residue was taken up in 0.12 mol l-1 KOH solubilization. For typical samples, recoveries varied from 94.5 to 105%, based on the amounts of both organic matter destroyed. The accuracy of the method was established by using a certified reference material (IAEA A-11, milk powder) and a manual method. The proposed flow injection method is now applied as an indicator of milk quality in a Brazilian milk production system.
ISSN:0910-6340
1348-2246
DOI:10.2116/analsci.14.559