Chromatography Forum

The system suitability test of single vial complies while that of 5 differently located vials in a tray doesn't comply (deviates by 10%).
What could be the possible reasons behind this problems?
Is it due the loop of autosampler or is it due to the sample retained in the injector?
Injection volume: 10ul

If you can get reproducibility from a single vial, it doesn't seem like a carryover issue. I have seen autosamplers where if the transfer tubing was not attached in the appropriate places it could become crimped when the needle moves to some locations, but not others and thus cause a variance in the amount injected.

When something similar was observed at one of our production plants (random high and low values, but completely reproducible within injections from each individual vial), I traced it to poor volumetric techniques and thorough mixing.

Hi Kanchan,

Sorry to follow you around...I still think I need to know a bit more to give you the best help I can...more details about what was done with the successful and the failed vials and/or vial slot on the tray. Please, see what you think. 10% variation is a lot--these were observed for each of the five vials that did not conform to sys suit, each having been injected six times?