Mr. Mahapatra,

There is unable to do this with UV-VIS.

Dear Sir,

I agree with the answer of Ivanova concerning the check of purity per UV-Vis.

Please note that you must have a pure dye as standard in order to see the impurities in your complex.

Another problem will be the solubility of your pigment in various solvents.

I send you hints for analysis.

- Have you synthesized the complex azo dyes or purchased? Important for the determination of impurities!

- Please test the complex azo dye ( if soluble as dye ) per TLC (thin layer chromatography) on slicagel p.e.

- Test the solubility in various solvents

- contact the suppliers (if purchased)

- I send you attachments in German and English.

- In the books of Zollinger and Abrahart, there are a plenty of hints about structure and analysis.

- The thesis (in German) of Brunner Albert (1929) about "Analysis of Azo Dyes" contains a lot of informations too. Try to find somebody for the translation.

JRG

Dear Mr. Manas,

Please compare the absorbance of the questionable dye with any standard.

Respected Jean R. Grezes,

Thank you very much for your kind information and advice.

Respected Bojidarka B. Ivanova,

Thank you very much for your words.

You could determine the molecular extinction coefficient of your sample and compare it to the literature value. In case of non-absorbing impurities, your sample's value will be lower...

If your complexes have unique absorption wavelengths (non-overlapping spectral region) and the extinction coefficients of pure complexes at those wavelengths in a particular solvent are known then it is possible to determine the purity of the complexes using UV-Visible spectroscopy.

To put it simply, there should be some part of the absorption spectra of each metal complex which does not overlap with others and also the extinction coefficient at one of the wavelengths in the non-overlapping region in a particular solvent must be known.