Chromatography Forum

My Hplc is ultimate 3000 hplc, suddenly I found problem in my autosampler as...random injection in my sequence appear as I inject blank no peaks appear although Iam sure from position of vial and its filling?! .., when I reinject the sample normal result appear... I check with agent of hplc in my country.. Didn't provide me with decent explanation or solution. Have any one face this problem with ultimate autosampler?

I had my Ultimate 3000 only do partial injections (~25 to 30%) at random intervals. It required a service call to fix. I never did find out what was the problem.

I had my Ultimate 3000 only do partial injections (~25 to 30%) at random intervals. It required a service call to fix. I never did find out what was the problem.

With me if calculate % of active api it is not more than 6 % of actual result... Did they provide you with any idea even weird one why this happen?! Did they replace parts of autosampler as rotor seal,loop or needle?!

Yes, they replaced normal service parts and did a needle realignment.

worn out rotor seal. it has 3 grooves, the groove attached to the sample loop is worn out. You may see no peaks on injection 1 because the sample slug is smeared against the rotor seal face. (cannot travel through groove)
Injection 2's peaks are actually injection 1 sample slug that found its way to the port OUT into the column via capillary action from valve switching. This is observed by poor area RSD.
See pic of worn out rotor seal groove under microscope.
Once flow enters any port of any valve LC or IC it can only exit the valve through an adjacent port. When the valve switches (load to inject) the flow comes out the other adjacent port.
Once you realize how the injector valve works, it makes troubleshooting so much easier.