Repeated Contamination

[WK]

Hi Rosie,
I always get a slight residue with my Autosystems and I use 100:1 split with volatile samples - I leave the split at 20:1 when not used.
The residue in the septum "ring" is less volatile sample residue but I also get "swarf" inside the septum nut on the threads from repeated tightening/loosening.
This I sometimes clean out. I wouldn't use 100:1 all day since I use helium carrier.
I should imagine PAH sample matrix is nasty.
Keep us up to date
WK

[Rosie]

Bhuvfe: Yes, it happens with a brand new liner. I've tried that before. It takes MANY blanks until I get a clean baseline. What temperature would you suggest to bake the inlet at after cleaning? I usually run at 360°C, which I thought was quite high.

Peter: You are quite right. A non-polar solvent makes much more sense. It might also help to use non-polar solvent to clean the guck out from the septum cap. That black residue is highly suspect.

WK: Running in split is not an option. I am exploring solvent effects, and cold trapping. I am running only standards at this point, no messy matrices. I do set the split flow to 25:1 when I am finished running. When you say, " "swarf" inside the septum nut", that sounds like the stuff I find when I remove the septum. But it's there everytime I change the septum, and the cap hasn't been removed since it was last changed (the septum).

I am due to do front end maintenance today. I will try extracting a piece of glove, and a septum, and attempting a stepwise procedure when cleaning the inlet. And, I will bake the cleaned liner in the GC oven before installing. I'm going to be a busy girl!

Thanks everyone for the suggestions!

[AICMM]

Rosie,

I would suggest you replace your split vent line. I don't know what liner you are using but you are shooting 2 uL splitless. My guess is that your standards are getting back up into your split vent line and slowly bleeding back out. Make sure you liner can hold the entire expanded volume of your injection under your current conditions. This would explain why lots of injections of clean solvent eventually come clean as the solvent backs up and "rinses" the split line out eventually.

Best regards.

[Rosie]

It looks like you may have been right, Peter. I tried extracting (separately) a septum, and a piece of glove with Et2O and there was a very high response, from the gloves, for the alkanes that usually appear in my chromatograms after an inlet cleaning. And all this time I was worried about protecting the liner from the oil in my fingertips - ha!

I am testing another brand of gloves and will then clean the inlet. Then I'll know for sure if the problem is resolved.

Thank you to everyone for the great tips/suggestions!

[Peter Apps]

Hi Rosie

Now this is what the forum is all about . I'd lay cash money at good odds that there are hundreds of chromatographers (including me) using gloves to keep their components clean. So much for that ! If you find a brand or type of glove that really is clean PLEASE post it. What gloves have you been using ?

Peter

[gcguy]

"I wouldn't advise anyone to use this system. I've been working with this very expensive paperweight for over 2 years and have had nothing but problems. We've had just about every board in the GC replaced, but we still get weird electronic problems with it."

I can sympathise with you on the reliability of this system. We have been running one for a couple of years and we have had nothing but trouble from it. It was a gift from another part of our company and I think it definitely disproves the saying about looking a gift horse in the mouth.....

I looked into the potential for solvent flashback into the split line as we have a pss and the liner volume is very small. Talked about it with a PE engineer at the UK headquarters and he told me that this could not happen. Obviously Boyles Law does not apply to PE instruments.
[/quote]

[WK]

Hi GC Guy and Rosie,
I have had 2 PE autosystems for 10 years now and they are very reliable (1 PSS, 1 CAP) - I have had to call engineer twice in 10years - they have a PM visit each year. I can't comment on the newer models though. I guess I'm lucky in that I don't overload the liner capacity too. Your models must be quite old since the Clarus has been the new GC for a while now? I have always had good service from PE.
WK

PS I use disposable nitrile gloves while packing liners - are they better than std lab gloves - I wonder.....

[Rosie]

Peter: Thanks so much! I have been using purple, powder free, nitrile gloves from a company called Ocean Pacific. I was initially doubting that the gloves could be responsible b/c I couldn't think of them having a lot of contact with the liner. But I just realized that I roll up the glass wool with my gloves on before putting it into the liner...

GCguy: I have had growing concern lately about this. I too have a pss injector, and the liner volume is quite small. I hadn't thought about it much until AICMM suggested it. I was really hoping the problem wasn't the split vent line! I was much relieved to see the contamination resulting from the lab glove extraction.

WK: I shouldn't have suggested that all PE instruments are damned. I am very glad to hear that someone has a reliable GC system of theirs. Ours just happens to be a lemon. And if I was offered a job in the future to work with one of these systems again, I would seriously think twice about it. Very seriously.

[WK]

Hi Rosie,
Good to see the problem is sorted - I have been using nitrile gloves to roll up wool too! Not a significant problem if I'm using 0.1ul at 100:1 though.
What experience of other GCs do you have previous to PE GC-MS?
Regards
WK

[Rosie]

WK: I've been spoiled a little. I've worked with a very rugged HP 5890. These GCs just go. They do what you say, and don't ask questions. I've also been using the newer Agilent 6890s at a gov't lab I visit on occasion. I'm afraid that's all I've been exposed to (other than the PE GC I currently work with). But I've only just started..

[gcguy]

We had a lot of issues when we first got the instrument and in general it works for a while then fails. The first fault was a small weld on the tower post failed, this caused miss alignment of the syringe. PE engineer could not find the fault, a third party engineer found it and we now use him for all things to do with PE.
Other failures include.....
main board fried,
PC ceased to function,
frimware corrupted,
constant dropping of communication between PC and instrument,
software upgrade not installing,
poor life time of the multipler tube,
frequent incorrect error messages when there is no fault,
tune files becoming corrupted.

The instrument is available about 50% of the time!!!

[zokitano]

constant dropping of communication between PC and instrument

Yeah, that annoys me a lot too. I have Clarus 500 with TurboMatrix 40 headspace sampler and every year different problem seems to come up with the system although it is not used frequently.

And yes, we have so poor service support in my country for PE products, that you wouldn't like to know about it.

Regards

[Rosie]

GCguy: That sounds like the instrument I'm working with. It only works about 50% of the time. We get error messages all the time too. The service engineer told us to ignore them. We've had the autosampler board, power distribution board, and some other board replaced. If the instrument doesn't run something for a couple of days, when I come back in to check on it, the GC has shut itself down claiming a "hardware fault." This happens all the time. I've set it up to run samples overnight, and come back in the morning to find that it decided to stop flowing carrier sometime during the night for no apparent reason (full gas tank!). We've had communication problems as well. The service engineer from PE came in and told us he couldn't fix it. It was down for ~8months. The service engineer who is always sent doesn't know much about how the instrument operates. All he knows to do is to replace boards. So if something is wrong, he finds the board corresponding to the problem and replaces it. If that doesn't work, he tries a combination of boards.

[gcguy]

Rosie,
We were lucky to find a third party contractor who was able to fix most of our problems after the poor service we got from PE. Even though we still have issues constantly with the instrument, between us we have always found "work arounds"
He used to work for PE and has now set up his own business unfortunately he is in the UK so not much use for you.

GCguy

[zokitano]

Two days ago we had (incomplete) annual PM of the PE Clarus 500 from the field PE engineer. The process of this years PM however is still in progress...
And again is the same old story: unproffesionalism by the engineer is well known in my lab and we aren't able to make contract with other service engineers regarding the PM or service of our instrument, because there aren't any.

Every problem that might come up during our work or (recently) during the PM by the enginner, is a new "science task" for the engineer. He loves to take pictures of the instruments or error messages and to send them back in European PE Headquarters for help. BTW, he is a electrical engineer, and have a very poor knowledge in chromatography/chemistry.

Because out lab is within the University and it is accreditated for drug quality control according to the ISO 17025 standard, we have also our "musts" (demands) regarding the test should be performed in OQ/PV of the PE Clarus 500 and regarding the documentation backing up those tests. The annoying part of the story is that not only the PE engineer doesn't know anything about this standard but also assures us that PE service doesn't do these tests (general tests like: ovent temperature check, detector linearity check, carrier gas pressure/flow tests etc).

I wonder if it would be a wise step for me to inform the PE headquarters for their very poor service engineer for Macedonia and Serbia. We are almost 5 years unhappy with our PE service and our instrument too.

As a last resort, we are considering to sell the Clarus 500+TurboMatrix40 Headspace sampler, and to buy other (probably Agilent) GC for which we are having excellent support and cooperation. I know this because we have Agilent 7890A GC with 5975C MSD already

Regards