Problem with Cleaning system

[StephenO]

Hi I have a HPLC Method and everytime I use it I have to wash the system thoroughly (24hr plus) afterwards or else there are peaks present in the next run I set up.

The mobile phase contains Dimethylformamide has anybody experienced problems using this before and can they recommend anything to clean it of the system quicker.

We know now that the carryover is not comming from the needle as the last time we set up the method no injection were carried out and we still got the peak in the next setup.

Thanks

[DR]

Whether your carry-over source is a needle contaminant is a function of your system's design, not necessarily of whether or not you made an injection.

What kind of system are you having this problem on?

[StephenO]

Waters 2695 with a 2489 Detector

[BFR_83]

Waters 2695 with a 2489 Detector

Hi!!
What's the composition of your wash solvent? Remember that this mixture must dissolve your products in order to eliminate possible contaminations in the next analysis.

If you are using a wash solvent that lead to product precipitation, there could be a possible reason for your problem.
Why are you using Dimethylformamide in your mobile phase? That's not very common.

I'm actually working with a Waters 2795, a system that is very similar to yours.

I hope you understand my English... Sorry in advance for the possible mistakes...