We are running Pancuronium Bromide on an HPLC system: (note - does not absorb well in the UV)
L1 column: µbondapak C18
methanol 30/ water 70, 0.005M B7, pH3 mobile phase
Detection wavelength 215nm
Samples and Std made up in mobile phase
Problem experienced:
The peak shape of sample slants forward whereas std is upright
Have concluded that something in the formulation of the product is causing the problem as on preparing std and including excipients present in the sample the std peak also slants
We have tried adjusting pH of std and sample without much success
pH sample - 4,0
Any suggestions would be appreciated
Thanks

what is the retention time of the pancuronium bromide? Try reducing the MeOH level, and retain the compound more. I've analyzed other quat. amines with 0.05% TFA (pH~2.5), with no problems with peak shape.

what are your excipients? are they ionic? can you remove them from the sample? They may be bonding with your analyte of interest once dissolved in the mobile phase. Try a high pH above your pKa, a few injections shouldn't hurt the column that bad if you're willing to try. You'll probably have to adjust the strength of the mobile phase to account for increased retention. If this works you can find a column that can handle this pH range.