Probable Methodology Fault

You have:

• ruled out user error
• used a known method to evaluate the systems performance

but are still getting variable results; this indicates a problem with the method robustness. If the method works intermittently, it is likely that it is just a matter of “balancing” the methodology, for example:

• the mobile phase pH is not quite right
• the column compartment may be too hot (or cold)
• the gradient may not have enough / too much organic solvent

Look at the injection size. Are you near / over the capacity of the column? Still not getting anywhere, why not call our technical support team for advice on 01227 265333.