Chromatography Forum

Hello,

I'm developing a new HPLC method and I noticed that as I was entering the injection amount I saw an option for "Standard Injection" or "Injection with Needle Wash." What is the difference between these two? Is there a preference?

B

On the Agilent 1100, needle wash actually dips the needle into a designated autosampler vial containing wash solvent. This option is there for those who wish to rinse the outside of the injector needle (the inside is constantly being flushed with mobile phase) except during the injection cycle).

What autosampler do you have?

The problem is that issues with carryover on the 1100 are most often associated with needle seat contamination issues which makes the needle wash virtually redundant. I prefer to run with it off.

Hi

Also to add, if you do use the needle wash remember not to have a cap on the vial and to regularly change the wash solution. Overall my experience is the these two things don't happen.

We use Agilent 1100, and would rarely, if ever, use needle wash.

Thank You!!!

hm, I personally use the needle wash. What does it cost? One vial, and 30 sec to set it up. I can't say I've ever looked in detail to see if it's necessary though. And LCbob, I never use a cap on the vial, and I replace the wash vial every sequence, without fail. You're right, there's no point otherwise.

could you explain why the vial must not be capped? Thanks