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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: stdacet on December 06, 2015, 02:21:22 AM

Title: Yellow Colored Solution in Acid Digestion
Post by: stdacet on December 06, 2015, 02:21:22 AM
For wet acid digestion from fish meat matrix, currently I use conc. HNO3, hydrogen peroxide (1:1) (10 ml). The solution that remains after digestion should be colorless, but I always get solution with yellow color. After evaporation, the volume of the solution remains about 5 ml, but still its yellow.

According to literature,  the hydrogen oxide suppresses the yellow nitrous oxides, but still I am getting it.

Can anyone suggest a solution for that.
Thanks
Title: Re: Yellow Colored Solution in Acid Digestion
Post by: discodermolide on December 06, 2015, 09:58:53 AM
What concentration of hydrogen peroxide are you using?
Maybe you need to ensure it is still OK?
Title: Re: Yellow Colored Solution in Acid Digestion
Post by: stdacet on December 07, 2015, 12:05:54 AM
Hydrogen peroxide is about 34.5 %, stored properly in dark.
Title: Re: Yellow Colored Solution in Acid Digestion
Post by: discodermolide on December 07, 2015, 04:14:09 AM
It is still worth making sure it is still 34.5%. Especially if it has been used several times.
Title: Re: Yellow Colored Solution in Acid Digestion
Post by: stdacet on December 07, 2015, 12:58:39 PM
Ok, I'll check it.  Can the amount of nitric acid added be a limiting factor, ? say for 10 g sample, 5 ml conc. nitric acid may not be enough?
Title: Re: Yellow Colored Solution in Acid Digestion
Post by: discodermolide on December 07, 2015, 01:09:05 PM
No idea, but probably not. I would go for the peroxide. But check the nitric as well.