Chromatography Forum

Hello,

I am newbie to this site, I found it looking for answers to this problem. So hopefully someone might be able to help me.

I have a CTC Combi Pal Injector on my GC-MS.

A Student was using 1% formic acid in the solvent some how got the plunger jammed/stuck in the syringe. I was not there to witness any of this. But from what I am told it mad a grinding noise and bent the plunger.

I have change the syringe (about 6 times since then because of bent plungers).

The problem is that every so often (fairly randomly) the autosampler will make that grinding noise (usually when doing a syringe wash) then the next wash it will withdrawl the plunger to far and bend it. I have pulled the unit apart and cant see any obivious signs of damage.

Has this happened to anyone else out there?

I think it might be a problem in the motor that drives the plunger but would like to confirm on this before i get the part.

Any help would be great............Cheers

Matt

The folks at Gerstel and LEAPTec have been very helpful whenever I have had any questions about wierd goings-on for any of my CTC instrumentation.

I have never had a problem with bending plungers, moreso with bending needles. Replacing the bungees usually helps with that.

Good luck.

It sounds like the plunger is sticking in the barrel of the syringe, the grinding is probably the stepper motor missing steps because of too much friction.

1% formic acid is a very unusual wash solvent for GCMS use, what are you injecting?

Hey,

thanks, A student was injecting Free fatty acids and used the same solvent in the cleaning cycle as in his samples.

I think your right about the stepper motor. I am not using the 1% FA in the as a solvent but the problem still occurs.

thanks guys for your help.

anyone else out there seen this problem

M

-Is the bending happening with just a common washing solvent (e.g.methanol)?
-Is it only happening with the formic acid samples?
-What are your speed settings for the washing?

The plunger bending is normally related with stucked/glued syringe,meaning that the solvent wash is not the good one for the type of product you're injecting. I normally use solvents like:THF,toluene,MeOH,etc. However when you choose the solvent washing you have to check if there is any interaction with your analyte and inlet conditions!

As Schmitty suggested replacing the bungees (black elastics at the side and back of syringe support) helps with plunger and more with needle bending.

Regards,
At_om

-Is the bending happening with just a common washing solvent (e.g.methanol)?
-Is it only happening with the formic acid samples?
-What are your speed settings for the washing?

The plunger bending is normally related with stucked/glued syringe,meaning that the solvent wash is not the good one for the type of product you're injecting. I normally use solvents like:THF,toluene,MeOH,etc. However when you choose the solvent washing you have to check if there is any interaction with your analyte and inlet conditions!

As Schmitty suggested replacing the bungees (black elastics at the side and back of syringe support) helps with plunger and more with needle bending.

Regards,
At_om

Hello, The Tech staff I deal with in NZ have installed a new stepper motor but I have a new problem.

It seems to me that the injector is working opposite to what is should do. When I install a new syringe it pulls the plunger right out of the barrel. Then when I try to do a fake wash cycle (I remove the plunger) the injector is moving down when it should be sucking solvent up and moving up when it should be pushing into the waste.

Has this happened to anyone else? Is there a setting wrong? Is something been installed incorrectly.

I am very frustrated right mow and the samples are building up

Cheers for your help

Matt

It sounds like the ROM needs to be flashed. The ROM can become corrupted at times, and if it does strange and unpredictable things can happen. Fortunately the ROM is on a EEPROM, and can be reloaded easily. If you have backed up the ROM it can be reloaded using PAL loader.

Hello Ron and anyone else who could help

I am not completely tech savvy when it comes to this injector so I would love some more help.

Here is the info. Our IT department changed all computers recently and even though I tried to keep the computer that was connected to the GCMS they would not let me. Anyway the short end of this is when I went into PAL loader to see if there was a back up file to update the injector that there wasn’t any. I have been talking to the Tech people here and there say the same as Ron that the Firmware could be corrupted and needs to be refreshed.

How do you go about this? Is it a big job? I am quite remote and don’t have anyone close who can help me with this.

Cheers for you help

Matt

Ron, I really dont understand what you mean by this "ROM is on a EEPROM," can you ellborate for me?

cheers

Matt,

There is an old type of erasable programmable read only memory chip (EPROM) that requires the use of a UV light source to wipe out the old memory. This is inconvenient due to the likely need to remove the chip to subject it to the UV light. In fact, the exposure window of some EPROM chips are covered with a UV opaque plastic instead of a UV transparent quartz - making them non-erasable for all practical purposes.

A newer type of EPROM is electronically erasable (EEPROM). This makes the process of wiping the old ROM instructions and reloading much simpler.

Bill

Thanks bill for the definition.

could someone step me through this process if possible?

Matt

The process isn't difficult, but since there isn't a backup file you will have to get a new ROM to download to the CombiPAL using the PAL Loader software. The distributor you bought the instrument from should be able to get you a ROM file. Distributors can download these files from a special CTC web site set up to support distributors. I would first search the computer hard drive and see if there are any files with a .sss extension. This is the extension that CTC uses for firmware. A backup of the ROM is supposed to be created at the time of install, unfortunately this step is sometimes skipped.

I have cracked the problem. The motor was wired in the wrong way. The logical way to wire is the wrong way. the new supplier of the motors for the injector (have changed) and the colour code is different. Anyway I reversed the plug and it seems to work fine.

I also flashed the rom and reprogrammed the Pal. It wasn' t that hard, and a skill to learm.

Thanks for all your help on thes guys