Chromatography Forum

Carryover and contamination is one major issue we handling everyday in HPLC lab. We have been involved numerous discussion about carryover/contamination but have not gotten the complete picture about when and where the contamination/carryover could happen inside an HPLC system? Does anyone here have a video which showing how the parts move while the mobile phase and sample are flowing so that we can see the potential spots where analytes can be retained and become carryover for following injection? Or simply some stepwise slides/cartoons. I, and many others like me, will really appreciate.
I am using Alliance and Acquity this moment.

It is usually not a problem with the flow path, but rather a problem with adsorption to seals.

Or the outside of the needle - if a needle wash is not employed, it would be easy to see carryover from a concentrated sample into the next run.

there are 2 main types of injection
pulled loop and split loop,
both work differently and carryover issues are different
even if the type is the same between vendors and even modules from the same vendor there are difference in the way it works and how carry over is handled,

to better know how to deal with a carry over issue you need to know details of the application and especially the instrumentation used

I'm still having injection carryover even after considerably increasing the needle wash time in the Alliance system. The injector has 3 main components, syringe, holding loop, and loop size, and somebody also mentioned seals that can contribute to carryover. Any other suggestion on how to deal with this problem.