CTC PAL autosampler x-axis errors

[emmasherman]

I have an intermittent problem with my combi PAL GC autosampler. I am running SPME and when moving a vial from the agitator back to the tray after injection (right to left) the arm seems to stick at a point on the x axis, it then tries to put the vial down but it is not at the correct point over the tray. It never sticks when going left to right though. Turning it off and manually moving the arm back and forth a few times helps for a while but the errors always come back.

Could it be that the cog and track inside the x axis need cleaning and re-greasing? If so what is the procedure and materials required to do this?

I have been recommended to use IPA and Vaseline by a colleague but if there are any users who have had this problem or technicians who know what to do I would appreciate your advice.

Thanks.

[Forse]

You will need a set of torx screwdrivers to take the autosampler apart.

I would not use Vaseline near an autosampler, or to lubricate plastic gears. Use a dry lubricant containing PTFE or graphite.

[emmasherman]

Great thank you for the reply.

I have taken the end of the rail off and the cog and track look and feel like they are made of metal. Is a dry lubricant best for metal gears? And should I clean the old grease (and dust) off with IPA before applying the new grease?

Thanks.

[Forse]

I have taken the end of the rail off and the cog and track look and feel like they are made of metal.

Ok. it is probably metal then. I would still use a dry lubricant. Vaseline is a petrolium based product, so I would not use it near an autosampler for fear of contamination.

If you have the autosampler appart I see no reason not to clean the old grease and dust off. IPA is good because it will not harm any electronics in the autosampler.

[BMU_VMW]

The lubricant used by technicians when doing maintenance on our CTC/Gerstel autosamplers is a 'vaseline' like grease.
I don't see how lubricant from the gears in the back of the autosampler can make its way to the needle (unless you are really over doing the lubrication )
Just clean up the old grease, check the gears, rails and the little metal weels to see if they are all ok and undamaged. Lubricate them. (I would use a vasaline like grease, but make sure it does not go to liquid by the GC's temperature)
And don't forget to check if the 'chain-belt', that makes sure kabels and wires are moving smooth, is ok. If this is blocked or not bending smooth it can cause bad movement of the autosampler.

obviously you will need to re-align to autosampler, so don't forget to take the syringe out before you do that. it will save you from a bent needle


EDIT: had a search on google and multiple vendors have a Prev. Maint. kit for combipal and in it is a package of "PAL-grease" and a brush to apply it.

[la_donz27]

Hi;

The last poster is correct; you need to order the PAL Maintenance kit. It will have directions what to do, and more parts than just the lubricating grease and brush. You are advised to do the complete maintenance if it hasn't been done in the last year.
The PAL has two "bungie" type cords that stretch over use and must be replaced. Also a white ribbon type band for the horizontal band that also needs replacing.
Use a Kim-wipe to clean off old grease, and brush on the new onto both the guide rod and the wheels. It's all in the document so it's not too hard, but it will take a little time.

Best of luck,

D

[emmasherman]

Thanks for the replies. My issue is the movement of the x-axis and from reading the PM documentation for the PAL Maintenance kit (found on a university website, CTC doesn't seem to give the information away) it only deals with the maintenance of the part the houses the syringe. That part is fine, the bungies are not loose and I have only bent one syringe in the last year (my fault - the alignment was off).

The grease in the maintenance kit is probably used all over the whole unit, but it seems rather expensive to order the maintenance kit just to get the grease! I am currently running SPME so reducing the ambient volatiles by not using petroleum based grease is probably a good thing.

FYI I haven't yet done the clean and re-grease, moving the arm manually backwards and forwards over the sticky spot has fixed it for now. Once all the important samples are done I will spend some time on it.