Issue 1, 2001

Continuous and stopped flow injection for catalytic determination of total iodine in urine

Abstract

This paper describes the use of flow injection (FI) techniques for the determination of iodine in urine, based on the catalytic effect of iodide in the redox reaction between Ce(IV) and As(III). The proposed procedures minimize errors in the conventional batch method arising from the reading of absorbance at a fixed time after addition of Ce(IV) reagent. Two FI systems, for the continuous and stopped modes of operation were assembled. In the continuous-FI system, a thermostated bath was used to increase the sensitivity. However this is not necessary for the stopped-FI system. The two systems are comparable in terms of sensitivity, sample throughput and detection limit. The continuous-FI and the stopped-FI exhibited detection limits (3σ) of 2.3 and 3 μg I l−1 respectively. Both systems have equal sample throughputs of 35 samples h−1. Calibration plots for both techniques are linear. The FI procedures provide very short analysis times compared to the batch procedure. Using the linear regression test, there is no significant difference between the results from the four methods, i.e., continuous-FI, stopped-FI, conventional method and ICP-MS. The proposed methods are readily applicable for automation and can be an alternative to the conventional procedure for the survey of the iodine deficiency disorder. A condition for sample digestion is also proposed to reduce the amount of chloric acid required for complete digestion. Kinetic information of the reaction can also be obtained from the stopped flow mode.

Article information

Article type
Paper
Submitted
04 Sep 2000
Accepted
03 Nov 2000
First published
01 Dec 2000

Analyst, 2001,126, 121-126

Continuous and stopped flow injection for catalytic determination of total iodine in urine

D. Nacapricha, S. Muangkaew, N. Ratanawimarnwong, J. Shiowatana and K. Grudpan, Analyst, 2001, 126, 121 DOI: 10.1039/B007131P

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