Abstract
Iodine deficiency leads to deficiency of thyroid hormones, which causes mental retardation in infant. Laboratory confirmation is important in its diagnosis. The major problems associated with the existing methods for iodine determination in milk samples are: 1) nonsafe alkaline solution; 2) harsh thermal condition; and 3) extra time required to complete various steps. In this study, a simple and rapid colorimetric method was investigated, which used acid digestion in combination with a rapid microplate reading format method to determine the total iodine content in milk. Sample digestion was done on 50โยตL milk in metavanadate/perchloric, at 230ยฐC for 10โmin. After digestion, iodine determination was based on the SandellโKolthoff reaction. The reaction results were read in 96โwell microplates by an enzymeโlinked immunosorbent assay (ELISA) reader. The determination range of the assay was between 2 and 40โยตg/dL. The withinโrun coefficient of variation percent in three levels (3, 12, and 36โยตg/dL) ranged from 6.7 to 9.3 and betweenโrun coefficients of variation ranged from 8.6 to 12.3%. The results obtained (n=70) by the optimized method have good correlation with the results of alkaline incineration as a reference method (n=70; r^2^=0.907; y=0.952x+1.77). Recovery tests for accuracy assessment in six levels from 6.2 to 34.2โยตg/dL) were between 91.3 and 113%. This method has enabled us to achieve 0.12โยตg/dL sensitivity. The results of this study show that a quick acid digestion combined with mild thermal and low sample volume with a quick reading of assay results were the main advantages of the acid digestion and microplate reading format. J. Clin. Lab. Anal. 21:286โ292, 2007. ยฉ 2007 WileyโLiss, Inc.