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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: vsagikis on January 20, 2017, 02:46:06 AM

Title: azo-dye spectrophotometry color development fails
Post by: vsagikis on January 20, 2017, 02:46:06 AM
Why this reaction occasionally produce conglomerates instead of the nice purple color we use to quantify parabenzoic acid?

Reaction
1. Sample containing parabenzoic acid as analyte + NaOH; boiling; + HCl to pH 2
2. + sodium nitrate - to form the azo bonds
3. + sulfanilamide - to react extra nitrite
4. + azo-dye: (N-(1-Naphthyl)ethylenediamine dihydrochloride (NED))



the more analyte in the sample the faster the sediment shows up in the sample, the color is pinkish when sediments present (https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2F&hash=03ee70165653ed1fcf3a617a5e4320ea)