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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: welfinger on April 16, 2014, 04:00:15 PM

Title: Analysis of Cr(VI) in soils with UV-Vis
Post by: welfinger on April 16, 2014, 04:00:15 PM

Hello,

I am trying to use the EPA methods to analyze for Cr(VI) in soil using a UV-Vis.  I have been having issues wtih color interferences even after filtering, increasing my absorbance levels.  I believe it's mostly organic material causing the problem.  I have not seen this in plain sand samples. 
Does anyone know of a way to correct for this problem?  I have tried using a turbidity correction, but it didn't work.

Thanks!

Title: Re: Analysis of Cr(VI) in soils with UV-Vis
Post by: Archer on April 16, 2014, 10:02:14 PM

Quote from: welfinger on April 16, 2014, 04:00:15 PM

Hello,

I am trying to use the EPA methods to analyze for Cr(VI) in soil using a UV-Vis.  I have been having issues wtih color interferences even after filtering, increasing my absorbance levels.  I believe it's mostly organic material causing the problem.  I have not seen this in plain sand samples. 
Does anyone know of a way to correct for this problem?  I have tried using a turbidity correction, but it didn't work.

Thanks!

Can you provide an overview of the method, what is the principal behind the assay and what wavelength are you using?

A link to the method would be useful if it's in the public domaine.

Title: Re: Analysis of Cr(VI) in soils with UV-Vis
Post by: Yerbol Abzhamiyev on May 13, 2014, 10:08:55 AM

Quote from: welfinger on April 16, 2014, 04:00:15 PM

Hello,

I am trying to use the EPA methods to analyze for Cr(VI) in soil using a UV-Vis.  I have been having issues wtih color interferences even after filtering, increasing my absorbance levels.  I believe it's mostly organic material causing the problem.  I have not seen this in plain sand samples. 
Does anyone know of a way to correct for this problem?  I have tried using a turbidity correction, but it didn't work.

Thanks!

Helo!
Telling the true, there could be many reasons why this happened. 70% of analytical mistakes occur during sample preparation. Were Your samples prepared in proper way? How did You do sample digestion?

Title: Re: Analysis of Cr(VI) in soils with UV-Vis
Post by: Archer on May 13, 2014, 01:30:05 PM

Quote from: Yerbol Abzhamiyev on May 13, 2014, 10:08:55 AM

Helo!
Telling the true, there could be many reasons why this happened. 70% of analytical mistakes occur during sample preparation. Were Your samples prepared in proper way? How did You do sample digestion?

27% of all quoted statistics are guessed rather than calculated.  :)