Base line separation of impurities

[mskishore13]

Hello,
I have been trying to separate the impurities in the API with GC-FID using a glass column, packed with 3% G-16 phase. I could able to separate all the impurities except one inmpurity which is not base line resolved. The impuriy comes right after analyte but was not baseline resolved. I moved from 3 mm ID X 2 meter column to 2mm ID X 3 meters columns but still no improvement.

Can you please suggest me possible other trials that I could separate?

What are the USP specification for the impurity separation? I mean Resolution.

Best Regards,
kish

[chromatographer1]

you might try a capillary column in a megabore 0.53mm ID dimension with 1 to 3 micron film and a flow rate of 10-15 cc/min in your packed column instrument to get more separation.

Rodney George

[grzesiek]

"What are the USP specification for the impurity separation? I mean Resolution. " - what are your clients needs?

"The impuriy comes right after analyte but was not baseline resolved. " - so how much is it resolved?

[mskishore13]

Hello,
Ther R=1.6 but not baseline separated. Like a vally peak.To validate the method (ICH) we need baseline separation.

Thanks,

[grzesiek]

"To validate the method (ICH) we need baseline separation. " - who says that?

[mskishore13]

Is the impurity needs to be baseline separated for validation of analytical method?

Regards

[chromatographer1]

It is interesting that going to a 3m from a 2m and from 3mm ID to 2mm ID did not make any difference. I suspect the longer column was poorly packed.

You also might try changing the phase loading on the support, or choose a different support, Chrom P-NAW instead of Chrom W-HP.

If you can describe the analytes involved (paraffin and olefin, for example) I might suggest another column and modification of the packing.

You can email privately if you do not wish to discuss the problem publicly.

best wishes,

Rodney George
consultant

[grzesiek]

"Is the impurity needs to be baseline separated for validation of analytical method? " there is no such obligation as far as I know