Ion-pair equilibration time

[EH]

I'm using Zorbax SB-CN and heptanesulfonate:ACN (97:3) as mobile phase. It seems like it takes almost full day to have the column fully equilibrated. If it's not fully equilibrated, I'm having some resolution issue in the early portion of the run(2-3 min).
Any recommendations or past experiences?
BTW, this is for catecholamine impurity method.

Thanks,

EH

[tom jupille]

This is probably not much consolation, but some people have it worse. Look at this thread in the archives:
http://www.lcresources.com/discus/messa ... 20010652am

A shorter chain ion-pair reagent might equilibrate more quickly, so you could move to hexane or pentane sulfonate, but you would have to use a higher concentration.

Alternatively, leave the column in the mobile phase for storage (this may hurt column lifetime, but should keep it closer to equilibrated).

[SIELC_Tech]

If you want to avoid lengthy equilibration time you might want to consider an alternative method for catecholamines on Primesep column.

You can use isocratic method and retain your products from 2 minutes to 30 minutes. Ion-pairing reagent is embedded on the column:

http://sielc.com/application_044.html

http://sielc.com/application_040.html

http://sielc.com/compound_101.html


Equilibration is very fast (3-4 column volumes for the same buffer). If you are changing nature of the buffer then check the following link for equilibration times:

http://www.sielc.com/MethodDevelopment_ ... ation.html

You can adjust retention time by modifying amount of ACN, buffer concentration and nature, pH of the buffer. You can achieve different selectivity by mixed mode chromatography:

http://www.sielc.com/Technology_2D_Properties.html


Regards,

Vlad

P.S. I am associated with the company making these columns.