Re: Spectrophotometer Help

Rosnilda_at_gmail.com
Date: 03/29/05 

Date: 28 Mar 2005 18:15:20 -0800

Hello Dan
I write that I look that maybe interfere in your analisys.

1. Permanganate is violet and absorb in yellow-geen
2. Permanganate need protection from the ligth.
3. The absorbance is not more than 2 as law.
4. For the custom of your graphic it grow up and up and then go down,
that said that maybe the lectures are very high and the equipment don't
have the option to read it or have interferences that bond the absorbet
composite.
5. I think as you that you have a problem of concentration.
6. An strategy is made some dilutions and see about 400nm if read the
concentration.
The dilutions you can made all from one stock solution or one from
another.
1mL in 10mL of H2O, 1in 100, 1in1000 if you need linearity or can use
1 in 100, 20 in 100, 40 in 100, 50 in 100....from your stock for only
dilute.
You are the expert in your analisys, only need to know your instrument.

Remember the KMnO4 is freshly prepare and degradate with the light, put
the solution in ambar bottle or put black paper around the bottle, some
laboratories use aluminium paper around the bottle but if the light
pass from a hole it work as mirror and reflec the ligth to others point
inner the bottle.

Maybe sonic the stock solution for a good dilution of all the crystals.
If don't have a sonic instrument shake well, very, very well. Maybe can
filter the solution to eliminate degradation particle (oxidation
brownishes particles that put as film in the wall of the volumetric
flask as in the bottle of grape juice)

Use purified water to dilution.

I can ask to my peer if it don't resolve your problem.

Maybe you can't understood me because it isn't my first languaje but if
you have another question or need clarify, you can wrote to
rosnilda@gmail.com