Chromatography Forum

Hi.

I have been using my Dionex system with an ASI 100 autosampler for analyzing Melatonin in Phosphate Buffer. These are my operating conditions:

Solvents: 40:60 of acetonitrile and water.
Flow rate: 1 mL/min
Column Temperature: 30C
Injection volume: 30 microliters

Everything had been working fine for 4 months, until the autosampler arm suddenly got stuck. The error message was "vial pusher obstructed". I remember that on this day, I had run more than 15 samples on a stretch.

I tried changing the maximum vial height option to 53mm and it worked for a couple of days before getting stuck again. The needle moves to the sample vial, takes the sample and moves back to the needle port, but gets stuck while moving down towards the needle port. When I manually push the vial pusher down during this operation, the needle moves down to the port and injects the sample normally and everything works fine. However, for the next sample the arm gets stuck again.

Can you help me out with this? It would save me a lot of time, if I can get the autosampler to work again.

Thanks,

Hi.
Everything had been working fine for 4 months, until the autosampler arm suddenly got stuck. The error message was "vial pusher obstructed". I remember that on this day, I had run more than 15 samples on a stretch.
.
.
Can you help me out with this? It would save me a lot of time, if I can get the autosampler to work again.

Thanks,

Open the ASI 100 cover and put a new coat of grease on threads of needle lifting mechanism and two column sliders, check the belt for demages and the whole gear for excessive resistance on motor shaft. Dismantling of top cover is described in manual.

Hi
Thanks for the information. I shall try doing that, but what kind of grease do I use for the threads. Will the ordinary grese do, or is there a specific grease that needs to be used.

Thanks,

Hi
Thanks for the information. I shall try doing that, but what kind of grease do I use for the threads. Will the ordinary grese do, or is there a specific grease that needs to be used.
Thanks,

Hello, Dionex calls Klueber Isoflex Grease (P/N 2182.5051) for maintaining LPG 680 pump. I'm convinced that this type of grease is excellent also for ASI-100 lifting mechanism. However, personally I used technical vaseline.

I would try to restore Dionex default settings from ASI-100 Main menu>Setup>Factory defaults.

What is port wear number and injections number of your ASI-100 (Main menu>Diagnostics) ?

Wojtek

Hi.

I shall try using technical vaseline. I have tried restoring the factory defaults, but apparently nothing changes. The port wear number is 5648 and injections number is 2971.

Thanks,

Hi

I have lubricated the threads with Dupont lithium grease, but still things don't change. The needle moves down perfectly while collecting the sample, but gets stuck while moving down towards the port. I think i should send it to service. What do you guys think?

Thanks,

Hi
... I think i should send it to service. What do you guys think?

Thanks,

If there are no visible signs of obstruction in lifting mechanism, then sending it to service seems to be the only practical way to repair it.

Happiness in New Year

Wojtek

Hi Wojtek,

Thanks for your helpful suggestions. No obstructions that I could find. I shall send it for service then.

Thanks