Chromatography Forum

Dear Friends,

1 - We must perform the Assay of Vitamin A (Retinol free) but we have no Standard Reference of this API. How we can do it if we have Retinol Palmitate Reference Standard, only?

2 - I am prefering to use an HPLC method, because we have to evaluate the Retinol Isomers.

Someone maybe help me?


Tank you,

Carlos Teixeira

I think it will be better to follow USP monograph for Vitamine A using corresponding USP Reference standard for assay by UV, after it you can apply suitable HPLC method for quantification of isomers.

I think it will be better to follow USP monograph for Vitamine A using corresponding USP Reference standard for assay by UV, after it you can apply suitable HPLC method for quantification of isomers.

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Tank you for your help, Maris.

I agree with You, Maris, but I have not the Vitamin A USP Standard, I have - only- a Reference Standard of Vitamin A Palmitate, oK?!

Maybe you send me other suggestion?

Best Regards,

Carlos Teixeira

Buy it, the Retinol ( Vitamin A) USP RS is available from the USP.

Dear Carlos,

Retinol as well as retinyl palmitate have similar molar absorptivities 52.275
1/M * 1/cm at 325 nm.

In the case, if your analyse is without retinyl palmitate and without extraction and is identical retention time on chromatogram for both vitamins, you could be try use retinyl palmitate as reference standard - I such think.

In the case of biological material or food or pharmaceutical preparate when extraction step is necessary, all reference standards and Internal Standard are necessary also. This requirements are also significant if sample contains retinyl palmitate and Vitamin A simultaneously- necessery separation of piks on HPLC chromatogram.

Source of reference standards - SIGMA, pharmaceutical producents of vitamin A (have also isomers, esters and analogs (complimentary)),
USA farmacopea standards (expensive).