Chromatography Forum

Hello,


I am trying to develope hplc method for benzodiazepines. Used phosphate buffer pH 3,7 and acetonitrile or methanol. Used isocratic and gradient conditions. 250 mm and 150 mm C18 column, with 5 micron particles. still can't reach full seperation for few of those diazepines. As i have DAD, not MS, need to resolve them anyway . So maybe someone of you knows hplc conditions for seperation of as many benzodiazepines as it could be . maybe it would fit for my mixture of diazepines. Almost all articles are dealing only with 3 or 4 ones in one run. So not good for me.

thank you in advance

Well, Google found this article:
http://igitur-archive.library.uu.nl/pha ... Benzos.pdf

I know it is MS-MS but it gives you the retention data of 33 benzodiazepines. You can easily find out which can be separated just by HPLC-DAD.

cheers,

Robert

It is not clear how many peaks you want to resolve.

Also, did you use mixtures of acetonitrile and methanol, or just the two solvents.

For some compounds in your class, a change of the pH is useful. Did you explore this, for example by going to a pH 7 phosphate buffer?

Did you ever play with temperature to finetune a separation?