1100 needle not seating

[db32]

Our 1100 autosampler showed a leak today, and I discovered that the needle isn't going into the seat. It stops 1-2mm above the seat, and the solvent just runs into the well and into the thermistor compartment. I've reset the autosampler (power off/on), but it still parks the needle high. It's been doing fine for several years, and I don't think we've changed any parameters. We don't have the control module, just control through our mass spec data system. I've looked through the manual and Agilent's Web site without success. Any suggestions? Thanks.

David

[HPLCCONSULT]

A few things:

(1) Make sure the screw that holds the needle in place has not come loose. The needle assembly is attached to a union and one screw is used to tighten it in the fully seated position. Under normal use it will not come loose. *My money is on this being the problem.

(2) Obtain a G1323A/B control module for future use in accessing the many diagnostic manual fuctions of the various modules. These can be purchased used or new. The needle 'height' function can be adjusted on the stepper motor to account for variations.

Also, please make sure that the needle has not been bent. You should always have a spare one on hand in case of a bent one or if a clog develops that can not be cleared.

Good Luck.

[Jackus]

If you have Chemstation SW switch to Maintenance/Diagnostics and select Replace Needle from menu (I don't know exactly where it is located. I'm not in front of analytical PC). Re-install the needle and reset instrument.

[db32]

Thanks for the suggestions. Unfortunately, the LC is controlled through a mass spec data system, and I don't have ChemStation. I don't see any way from the manual or Agilent's site to adjust the needle properly without the controller or ChemStation to allow access to the maintenance functions. Is that a correct assumption?

I've found a controller online at a couple of sites (labx, biodirect). They want $800-900 for one. Is that a good price, or can you recommend other sites?

Thank again.

David

[HPLCCONSULT]

Did you check #1 in my list ? Needle could have slipped 'up'.

Yes, it was clear from your post that you did not have ChemStation software so that is why I suggested you purchase a hand held control module, G1323A or B.

Used prices in the past few months have been between $250 to $900. The market is flooded with them right now as many have been sold at recent auctions. I would try and negiotate for a low price. The G1323B is worth a few dollars more than the 'A' because the firmware can be rev'd to a higher level (more memory & features), but for using the diagnostics it will make no difference.

Good Luck

[db32]

The needle might have moved. I was trying to move the whole assembly, which didn't move. When I tightened up the Allen screw, however, it was a little loose. I haven't tried pulling only on the needle. Is there a way to adjust the needle properly without the controller? I thought about loosening the needle, moving it into the seat, and then tightening it. I'm worried that the autosampler will think the needle is higher than it is, and start spearing things. If my idea is reasonable, how far into the seat is correct? Thanks.

[HPLCCONSULT]

The needle is part of an assembly which utilizes a union to hold it in position. The set screw secures the needle assemble. It fits in at a specific angle and seats itself in the correct position. Their is no adjustment of this assembly. The hardware has a software programmable features which can be used to adjust the position up and down (for drawing up a sample) as well positioning the lowest level the needle will go when inside a vial (so it does not hit the bottom). This requires the use of the ChemStation software OR the G1323A/B unit. *** The adjustment I am referring to involves checking that the needle has not come loose when it is in the home position (in the needle seat). If you loosen the set screw that holds the assembly, you can then push the assembly firmly into the seat and, while holding it there, tighten the set screw. Press down at the top of the bend on teh needle assembly when doing this to keep the needle firmly in the seat. This is actually easier that it sounds and if you look at it you will see what I mean. Do not bend the needle when doing this.

If the needle is still floating above the seat (causing it to not hold pressure and leak) when in the home position AND it is corectly seated, then you will need to make these adjustments via the software or G1323A/B as noted before as it obviously has been re-programmed or lost its correct home position.

[lmh]

The most likely explanation is that the union part of the needle has come loose, as suggested above, but if it hasn't, there is another obscure possiblity:

Do check your needle seat looks normal (i.e. has a small hole WITH A NEAT BEVEL in the middle). We've had, once, a needle get so firmly wedged in the needle seat that it pulled the middle of the needle seat out completely. It then "injected" the needle seat, through a septum, into a vial (where we found it a week later: never argue with an autosampler!). This leaves a gap of a few mm, exactly as you describe, between needle and "seat" (or what is left of the seat, which actually looks quite neat if you haven't got a real seat for comparison). Obviously it leaks like a sieve.

Good luck

[DR]

re:

Used prices in the past few months have been between $250 to $900. The market is flooded with them right now as many have been sold at recent auctions. I would try and negiotate for a low price. The G1323B is worth a few dollars more than the 'A' ...

Just a note - get one while you can via auction or used equipment distributor as these are no longer available new. The 1200 series will also work on 1100 modules but it's at least 10x more expensive than the lower end auction prices cited above (we've been there, done that in the past year).

[db32]

Thanks for all of your replies. My boss decided to just loosen the screw, move the needle down to its stop (it *had* ridden up), and see what the results were. It's seating as it should, it's not leaking, and it's not spearing the sample vials. Not the elegant solution I'd like, but it appears to have succeeded.

Thanks again for the help. I'll keep my eyes on the needle, and I'll also keep them open for a controller so that we can do things the accepted way if there's a next time.

David