Chromatography Forum

Has anyone tried Pramixpexole dihydrochloride method in Pharmeuropa ? I am having problems with this method which involves a gradient using ion pair reagent (sodium octanesulphonate). The blank is disastrous and the main peak is eluting at 1 min instead of at 8 min as is in the monograph. Column is an Inertsil 125mm x 4.6mm x 4um and packed by Capital.
Please help! Here are some images

[IMG]http://i36.tinypic.com/30ubmkg.jpg[/IMG]

[IMG]http://i34.tinypic.com/10i5ahj.jpg[/IMG]

[IMG]http://i35.tinypic.com/b4xen4.jpg[/IMG]

Can you list the method parameters, It would help to find possible points where errors could occur

Can you give outline details of the method.
Ion pairing and gradients don't work well as the ion pair reagents take a long while to reach equilibrium (sometimes several hours)

From observation of your chromatograms I am not convinced any of the peaks are from the active. Inject several strengths of standard to check area is increasing with concentration

Method details:

mobile phase A : buffer sol (9.1g of KH2PO4 + 5g of sodium octanesulphonate) in llitre of water. adjust pH 3 with H3PO4.

mobile phase B : ACN : BUFFER sol (50:50)

Gradient : A B
0 min 60 40
15min 20 80

solvent mix : ACN :Buffer (200:800)

From chromatogram, Highest Imp has a max absorbance of 3mAu.