Problems with impurities separation and peak definition

[lismc]

Hi,
I'm having problems with the HPLC method for Metformin and its Impurities. The problems are 2:
(Mobile Phase: Buffer Solution NaCl+PICB7 (0,5+0,5g/L) pH 3,85 97% : MeCN 3%; column 300x3,9mm; 10um packing L1)

Using this mobile phase I can't separate two degradation impurities (Metformin Related Compound B and Melamine), but I have a beautiful peak for Metformin.
To separate these impurities I tried a Mobile phase without the reagents, just H2O pH3,85 97% : MeCN 3%, using the same column. It was a success in terms of separation, but I lost peak definition for the Metformin peak!

I tried a gradient with MeCN : H2O pH 3,85 : Buffer solution pH 3,85 without any success!!

I already tried different columns, mobile phase composition, pH.... and didn't have any luck!

Can anyone help me??

Best Regards!

[mattmullaney]

Good morning lismc,

Perhaps this method if modified could be explored--not enough retention of metformin, the column seems needlessly long, maybe (if you do not care to quantify metformin, perhaps it does not matter):

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620513/

[lismc]

Good morning lismc,

Perhaps this method if modified could be explored--not enough retention of metformin, the column seems needlessly long, maybe (if you do not care to quantify metformin, perhaps it does not matter):

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620513/

Thank you for your reply!! But I do need to quantify Metformin!!

[mattmullaney]

Good afternoon,

My Pleasure.

Perhaps altering the initial gradient condition, the temperature, and/or a change in the stationary phase to allow for greater retention of polar species (the retention of metformin seems to be the only problematic point) could be explored? Of course, your time and sense are your own. Best wishes for your path forward!

EDIT: I almost forgot:(HILIC separation)

https://www.sciencedirect.com/science/a ... 3214004243

[Vlad Orlovsky]

Here is a mixed-mode approach for analysis of metformin:
https://helixchrom.com/compounds/metformin/

[mattmullaney]

@ Vlad,

Thank you, sir. Metformin retention is reasonable, by chance, do you have a chromatogram including any of metformin's impurities (Metformin Related Compound B and Melamine)?

[Vlad Orlovsky]

Since impurities are slightly basic they should retain similar to metformin.

[mattmullaney]

Thank you once again Vlad.

[lismc]

Thank you for your answers!
I'm almost done with my method!

[mattmullaney]

Hi lismc,

That is good to hear, metformin is an important drug for many people. Continued good fortune to you.