Chromatography Forum

I'm fairly new to this machine, however it's roughly 7 years old in this particular lab. Had an engineer in for 2 days replacing parts and doing a normal service call in order to restore reproducibility in retention times. Long story short, in an attempt to change the needle, he couldn't get it out (after lots of tugging/pulling) and had to bolt for a flight, leaving us to replace it the following day. Since then, we haven't been able to get the needle to align correctly with the needle seat, etc. How do we go about fixing this? Or is it a matter of getting Agilent to send their guy out again to fix/finish his job?

First of all, I'd be on the phone to my Agilent rep to complain - a needle exchange shouldn't take more than a few minutes - if he struggled, he didn't know what he was doing.

How far out of alignment is it? Just a little (a couple millimeters)? Or is it way off? Are you in the Chemstation diagnostic view, in the ALS maintenance part?

When you say "engineer", do you mean an Agilent factory trained person or someone else? Changing a needle in an 1100/1200-series A/S is a five minute job without the aid of the ChemStation maintenance (Diagnose) or Control Module to help (in that case it may take 10 minutes). In any case, if the product is under service contract, ask them to send someone else out to service it. If all you need to do is align the needle, then you should be able to do this in a few minutes by yourself. "Alignment" is done with the needle raised above the seat, a few to several millimeters, and bent using your fingers to adjust the needle in the direction needed such that it is perfectly centered in the needle seat. If it is not centered, if may core the seat and you will end up with other problems. Once centered, it should be fine for many years of use.

BTW: If by "alignment" you mean that the needle is too high and is not touching the seat, then you have not installed the needle correctly. The needle is part of a union assembly and the entire part is held in a cradle with one set screw. The assembly must be pushed down till it bottoms in this cradle and then the screw snugged up so the needle does not move.

HPLCCONSULT, I almost asked the exact same thing - Agilent or 'contracted by Agilent'. I had a service guy out from a secondary Agilent provider a couple months ago, and his idea of familiarizing me with a new module (after taking two hours to 'install' it) was telling me to 'read the manual, because he didn't know anything' about that type of module.

Also, perfect description of how to align the needle. Tampa, with that advice, you should have it aligned in no time.

"Contracted by Agilent" would be the description. The alignment is way off, as it's "home" right now is a few inches behind the needle seat position. My problem (and this could be the main source of our problem) is that it's in "shutdown" mode, and continues to give me an error when I attempt to fix it in the Chemstation Diagnostic, ALS maintenance part. Resetting the injector puts it in the same place everytime (behind the needle seat and off right a few cm's), and then goes back to the same error.

From here, I would power down the system. Then I would try to get the needle out of the holder, then power back on, then go into the Diagnostic View and start the process from the beginning. Can you get to the set screw in the clamp assembly (near the union)? If not, you might need to temporarily remove the plastic sheath that separates the needle from the tray to get access to that clamp - and at that point, you may want to disassemble the stack and take the autosampler cover off and the top sheet metal piece for even better access.

Note: - If you mess with that plastic sheath piece, be very careful when moving it around - it contains the sensor that tells the ALS if the front cover is on, and if you harm it the ALS won't go to a ready state because it won't be able to tell if the cover is on or not.

These instructions are very good for the standard autosampler. If you have the well-plate version, the needle change is more complex (although not all that difficult). Which model is it?

Perhaps you've tried this already, but for me it worked: I extinguished the system. Close the Chemstation, and turns off the computer. Back on to the computer, the system, open the Chemstation, and resets the ALS.
Good luck.

Agree with above: replacing a standard 1100 autosampler needle (or seat or rotor seal or metering piston seal) is very straightforward.

I believe that the only real way the autosampler module can affect or cause your retention time irreproducibility issue is with a leak.

This doesn't add up. You haven't got the normal vial rack version of an 1100 autosampler have you? The needle cannot be more than a few mm out of position on this instrument, whatever you do. It can't be out by inches.

So after combining a few ideas above (taking the needle out, manually changing the x-axis of the holder, resetting the system, etc etc), it finally has started working correctly. Thank all of you so much for your help. It was greatly appreciated.