Analysis of maleic acid

[praveenpaliwal]

Hellow,

I am anlyzing maleic acid on HPLC . I have Methanol and water as eluent with ODS column. I need maleci anhydride seperately. If I prepare the sample in methanol only then It may be possibility that anhydride converts in to ester. I think so , I need help on this veiw that I ma ging right or not.

Regards

Praveen

[Vlad Orlovsky]

There is no way to accurately analyze maleic anhydride by reverse phase HPLC due to hydrolysis or esterification of maleic anhydride. What you can do is quench maleic anhydride with ammonia for example or benzylamine and analyze it as amide derivative.

[oscarBAL]

I wonder if nonaqueous titration could be an aproach?
Tirate total acidity; and then non aqueous acidity; I don't know there is a long time since I did my last titration.


Oscar

[praveenpaliwal]

Sir,

Thaks u both for reply. I also did the exercise on HPLC . It was observed that we got two peaks and both are sharp. The area % count was found 88 % . I also checked total acidity on titration method and it was also found 87.67 % .
I am using RP technique and I had it chromatogram also. Can you both please main your address so that I can mail you the anysis condition as well as chromatogram also.
My cofusion is that maleic acid has two form d and l . Can these two from can seperate on RP- phase column rather than chiral cpolumn. It was wonder for me and sone fear also for telling. So I want to shair this from youn all . So please mail your address.

Regards

Praveen

[HW Mueller]

Since I always confuse malonic and maleic acids I consulted my old organic chem text. Maleic is an ethylene with two carboxyls, cis to each other. No chirality here. It is also very unlikely that you converted it to fumaric acid which is the trans form. Vlad practically told you what might have happened: you may be analyzing the acid (hydrolysis) + an ester (mono?).