Hello all. This is my first post. My lab is having a recurring error with one of our autosamplers. The instrument is an Agilent G4226A autosampler, part of a 1290 Infinity II LC system, attached to an Agilent 6420 QQQ. The system is named Han Solo.

The error is "Injection valve failed switching to main pass position [EE 4700, 100]". It occurs randomly, with anywhere from a month to a day between errors. It usually happens a few hours after we've left for the day. I think it might be between the 10th and the 20th injection - we've just started to keep track of the vial position and sequence position for when the error occurs.

The old autosampler had this problem for over a year. An Agilent engineer worked on it last year, replaced a part, and the problem went away for a couple of weeks. Two weeks ago, another engineer worked on the autosampler. He replaced the same part as before. After that the error happened on the first injection every time we tried to run a set.

Agilent's next step was an instrument swap. We connected the new autosampler last week. It worked fine, until yesterday evening, when the same error happened. One of my coworkers thinks it may be a firmware issue. Both of these autosamplers have the firmware version A.06.54 (006).