a subtle leak at the bottom of needle (1260 infinity standard autosampler)


My colleague notices that there is a subtle leak at the bottom of a needle (1260 infinity standard autosampler) when an injection sequence starts with needle wash.

Specifically, the needle draws his sample and before needle wash is occurring, he sees some solvent accumulated at the bottom of the raised needle. 

He only injects 3uL of samples and shows me an intensity difference with and without needle wash since without needle wash the injection upon the draw happens quicker than injections with needle wash, minimizing any losses due to the accumulation.

Is this a known artifact in this series? I have changed the seal of the metering unit but doesn't help to address the issue. 

Thank you!


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