Preparation of 1% iodine solution
Amit Agarwal
I know that I require Iodine and KI but in what proportions ?
Thanks.
Mohammed Farooq
> Can someone please guide me as to how can I prepare 1% Iodine solution
>
> I know that I require Iodine and KI but in what proportions ?
>
> Thanks.
You did not state the purpose of preparing 1% solution of iodine,
whether it is for iodometry or something else. The following is one of
the common procedure of preparing 1% (~0.078 M) iodine solution. Since
this corresponds to 10 g Iodine/Liter, you can adopt this procedure.
Dissolve 16 grams of KI in 20-30 mL of water in 1 L flask and transfer
approximately 10 gram of iodine to the concentrated solution of
potassium iodide and swirl till all the solid iodine dissolves. After
ensuring that all the iodine has dissolved , let it cool and make up
the volume with distilled water to mark and store in the dark.
Amit Agarwal
> wizk...@mailcity.com (Amit Agarwal) wrote in message news:<6d6e0636.04082...@posting.google.com>...
That was excellent. I need this iodine for determing starch in milk.
Would be great if you could suggest how you came up with these
measurements ?
Thanks again.
Mohammed Farooq
> That was excellent. I need this iodine for determing starch in milk.
> Would be great if you could suggest how you came up with these
> measurements ?
>
> Thanks again.
Preparation of iodine solutions can be found in any standard text of
analytical chemistry. However I scaled down the quantities for your
case (1% corresponds to approx. 0.078 M Iodine soln.) by simple ratio
and proportion.
For qualitative purposes (and for fun at home) ie detection of starch
in milk etc. you do not need such accuracy put a spatula of solid
iodine, two spatulas of KI, dissolve to make a dilute solution which
is now ready for starch detection. Even solid iodine placed on a bread
will leave a purple color showing the presence of starch.
Amit Agarwal
The starch test works perfect but I also use this solution for testing
Maltose in Milk. This is where it fails.
Any clues.
Thank you,
Amit
Mohammed Farooq
The iodine test is very specific for starch and *perhaps* no other
other polysaccharide forms a blue colored complex with iodine, maltose
however is one of the hydrolytic intermediate products of starch. I
feel you are doing some kind of project on milk if you need official
methods on milk analysis then AOAC books would help you secondly if
this is for academic purposes then I suggest the following:
Fritz Feigl: Spot tests in organic analysis (I have seen the inorganic
one) but this might contain many specific tests for maltose, the
beauty of spot tests is that you only require a *drop* of reagent, a
drop of analyte and a filter paper. The color formed on the filter
paper immediately tells you whether certain substance is present or
not, down to microgram levels.
Another book that should also be available in India (it is available
in Pakistan from National Book Foundation) is "Food Analysis- Typical
Methods and Interpretation of Results" by A.G. Woodman, this book is
very old but extremely useful for classical food analysis methods for
example Polenske method is given with a diagram.