Analytical Method: Iodine in table salt

Reagents:
Cat.No. 105445  Zinc iodide starch solution
Cat.No. 100716  Sulfuric acid 25 % for analysis
Cat.No. 116754  Water for analysis
 
Measurement range:
0.50 - 3.00 mg/l iodate at cell length 10 mm and 585 nm
 
Iodinated table salt contains 25 - 30 mg/kg of potassium iodate. This is added to prevent iodine deficiency disease of the thyroid. The daily recommended dose of iodine for adults is 150 - 200 mg.
 
Sample preparation:
The sample should be dried to constant weight at 105 °C and 10 g dissolved in water in a 100-ml volumetric flask and made up to the mark with water for analysis.
 
Analysis:
Add 1.0 ml zinc iodide starch solution and 0.20 ml sulphuric acid 25 % to 20 ml sample. Allow to stand for 10 minutes and measure against a blank comprising equal portions of water for analysis and reagents at 585 nm in a 10 mm rectangular cell.
 
Calculation:
Iodate content in mg/kg = analysis value in mg/l x 10

 

Parameter list for programming the photometer SQ 118

01 Method Iodate
02 Cat.No. -------
03 Measuring range 0.50 - 3.00
04 Units mg/l
05 Reaction time 10 0 min
06 Cell 10 mm
07 Wavelength 585 nm
08 Calibration Factor
09 Evaluation Linear
10 Factor 2.80

 
Calculation when measuring the absorbance value using the photometer SQ118 without programming the method in the memory of the instrument:

Measured absorbance
of samples in A
Result in mg/l
[A sample * 2.80]
1.000 2.80

Materials

     
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