By Dale on Friday, May 30, 2003 - 01:04 am:

Do anybody can help me to recoginize the problem becacuse when I follow the method below with a new column for Metformin Hydrochloride tablets impurity test refered in European Pharmacopiea , serious tailing problom come out:

The chromatographic procedure is carried out using (a) a stainless steel column (0.125 m?.7 mm) packed with a regular, porous silica gel to which benzenesulphonic acid groups have been chemically bonded (5 um) (Partisphere 5u SCX is using), (b) a 1.7% w/v solution of ammonium dihydrogen orthophosphate adjusted to pH 3.0 with orthophosphoric acid as the mobile phase with a flow rate of 1 ml per minute.

Thanks very much!

--------------------------------------------------------------------------------------------------------
By Anonymous on Friday, May 30, 2003 - 07:53 am:

YA I KNOW THIS IS ONE OF THE TEDIOUS METHOD FOR THE METFORMIN ANALYSIS

this method is giving almost wrong estimation due to diluted standard broad peak.

hey wehre are usp and ep persons do something for this?

--------------------------------------------------------------------------------------------------------
By Anonymous on Friday, May 30, 2003 - 04:51 pm:

The USP and the EP are taking on methods recommended by industry. The ethical houses take their worst methods to the USP, once they are running out of patent. The generics take these methods as if they were god given. And then they complain. God knows why...

--------------------------------------------------------------------------------------------------------
By Chris Pohl on Saturday, May 31, 2003 - 11:59 am:

I can't say I ever tried this method but here are a couple of suggestions:

1). If you're stuck with the European Pharmacopeia method and are simply trying to figure out why you are seeing tailing, possible causes include metal contamination, interaction with surface silanols and overloading. Treatment of the column with disodium EDTA should help remove metal contamination, lowering the pH would help silanol effects. Tailing might also be due to overloading, try injecting a less concentrated standard.

2). If you're open to trying another method, suppressed conductivity detection would be a better bet. Although we haven't run the specific compound, it's certain that you could perform this analysis on the Dionex CS17 column as we have performed the analysis of related compounds on this column. The method is quite sensitive and the column provides good peak shape for molecules of this sort.

--------------------------------------------------------------------------------------------------------
By dale on Saturday, May 31, 2003 - 06:23 pm:

Thanks for above person who have given me valuable
suggests and insights.

dale

--------------------------------------------------------------------------------------------------------
By Jan on Monday, June 2, 2003 - 07:51 am:

Hi Dale,
The concentrated solution (5 mg/ml if I'm not mistaking) is of course giving a broad and tailing metformin peak (overloading). But that's no problem, because you are only looking at impurities in that injection. The standard solutions are much more diluted (cyanoguanidine, melamine and metformin diluted) and should give nicer peaks. Anyway, with our 10-year old Partisil 10 µm SCX column, peaks of the diluted solutions are not bad at all!
Jan

--------------------------------------------------------------------------------------------------------
By Anonymous on Wednesday, October 15, 2003 - 08:07 pm:

I would like to know how we can improve the peak shape on this column , i am doing development for another compound not metformin but having NH2 group , so how to improve the peak shape of this .

i am doing same coumn with same buffer and PH 3.

--------------------------------------------------------------------------------------------------------
By BeverlyGreen on Monday, March 22, 2004 - 08:25 am:

Can the related/impurity compounds (4,6-diamino-1,3,5-triazine-2-yl)guanidine; N,N-dimethyl-1,3,5-triazine-2,4,6-triamine; and 1-methylbiguanide be purchased commercially. I have searched Fisher, Acros, Sigma, Aldrich with no success. thanks