OVI method 1

[Murshad]

Hi fellows

One of my co-worker has problem while doing this method. He is using DB-5 column. Around retention time of 1,4-dioxane he is getting a peak even in blank water. System is HP-6890. He has tried couple of columns. He has kept detector and injector temp at 325°C and 200°C for night and in morning he still has same problem.
All columns did not give any extra peak on 5890 system.

Any solution to this problem.

Thanks in advance

[wrighty]

It could be one of three possibilitues:

1, Injection system: is the syringe clean? are there adequate washes in between injections? are you using a liner? if so are there any obvious contaminants present?

2, Injector port: if using graphite ferrules, bits can come off and dirty the injector.

3, Detector: As the injector, the detector can become contaminated with the ferrules.

the first thing that i would do, would be to replace the syringe and run a blank. if the peak is till present cool down the system and check the liner. Finally, if the peak is still present, remove the column and clean the injector and detector ports. There are specialised kits that you can use but i use an old syringe plunger and get into the nooks with it. Care should be taklen and not too much force used in case you damage the detector.

hope this helps

steve

[Murshad]

Hi

Thanks for reply.

Syringe has been changed.

Liner has been changed.

detector assembly has been sonicated in methanol for 30 minutes but the problem still presists

[Murshad]

Hi

Is there any way to find that which one is actually contaminated, detector or injector.

Thanks a lot

[chromatographer1]

The pneumatics may have had dioxane backflashed from previous injections. Later injections are backflashing to the same air and washing some of the dioxane out.

Wash your pneumatics and try not to inject so much solvent in future injections.

best wishes,

Rod

[chromatographer1]

opps, area, not air

Rod