Rapid acid digestion and simple microplate method for milk iodine determination

Area of Science:

• Analytical Chemistry
• Biochemistry
• Food Science

Background:

• Iodine deficiency causes thyroid hormone deficiency, leading to infant mental retardation.
• Accurate laboratory diagnosis of iodine deficiency is crucial.
• Existing milk iodine determination methods are unsafe, time-consuming, and require harsh conditions.

Purpose of the Study:

• To develop a simple, rapid, and safe colorimetric method for total iodine determination in milk.
• To overcome the limitations of current iodine testing protocols.

Main Methods:

• Utilized acid digestion with metavanadate/perchloric acid at 230°C for 10 minutes on 50 µL milk samples.
• Employed the Sandell-Kolthoff reaction for iodine determination.
• Used a 96-well microplate format with an ELISA reader for rapid result analysis.

Main Results:

• Achieved a determination range of 2–40 µg/dL with a sensitivity of 0.12 µg/dL.
• Demonstrated high precision with within-run CVs from 6.7–9.3% and between-run CVs from 8.6–12.3%.
• Showed excellent correlation (r²=0.907) with alkaline incineration and recovery rates between 91.3–113%.

Conclusions:

• The developed acid digestion and microplate reading method is a fast, safe, and accurate approach for milk iodine analysis.
• This method offers significant advantages over traditional techniques, including reduced sample volume and mild thermal conditions.
• Facilitates efficient monitoring of iodine content in milk for public health applications.