Pramipexole EP method

[rejxil]

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]

[JGK]

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

[AdrianF]

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

[rejxil]

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.