[brbabu_1979]

Hi every one,
                    I am new to this forum. I have one question on UV spectrometer calibration. We were using potassium dichromate solution for accuracy of absorbance calibration test. Can anybody tell why we are using that? any scientific reason behind that. Provide me material about this.

Thans for your replay in advance
Babu

[Borek]

This page addresses titration, but some (if not most) of the remarks hold here as well.

http://www.titrations.info/titration-standard-substances

[JGK]

http://www.starnacells.com/d_download/RefCat.pdf

it's a well studied mareial and forms part of NIST's traceable STD repertoire

[marquis]

Actually, that surprises me.  The standards provided with the instruments are usually holmium oxide or holmium chloride.  They are NIST tracable as well.

[mariosm]

I do not know all the rational behind this but it is part of the EP 2.2.25 (European Pharmacopoeia) request. If you are using this solution, I recommand to use an acidic diluent (H2SO4) more concentrated than recommanded (0.01M instead of 0.005M) because since it is a strong oxidising agent, I suspect it to react with CO2 of the ambient air and once it is reduced, the absorbance becomes different. Acid prevents this reaction.

[brbabu_1979]

Thanks to Borek,JGK, mmarquis and mariosm for all your replays. I understand that pharmacopoeia were suggest that and instrument supplier were also suggests the same. But I am looking for any scientific reason behind this. Please if you have post me. Thanking you guys in advance

Babu