Chromatography Forum

I would like to do analysis of water on a PE GCMS using a 60m ZB-5. The water phase is complex and contains salts aswell as organic compounds. I am however worried about precipitation of salts in the column - or will all salts stay in the inlet/glass wool?

Also im not sure on the GC method that should be applied. Couldn't reallly find anything about GCMS on waterphase in the litterature. Thinking something like inj port = 150*C, starting oven around 120, injecting 0,5µL into a 900µL inlet and turning on the filament after ~15 min.

Does anyone have any experience doing this? Is it just a bad idea that would ruin my system? I have a FID available aswell, but would really like the qualitative features of the MS for this analysis.

If anyone has a reference to GCMS on waterphase it would be appriciated aswell!

Thanks :-)

Try with SPME, PDMS fiber. After sampling rinse with milliQ water, carefully remove remaining water from fiber and inject.

Basically water could not be injected into GC because make activation of analytical column and other drawbacks.

Ciao.
Roby

I have injected wine with a 1 ul splitless injection to GC-MS, not more than half a dozen samples - the analysis; for propylene glycol from a potential aintifreeze leak worked OK. The long-term effects are not likely to be good, so avoid it if you can.

Peter

I'm a GC/MS guy but wouldn't it make more sense to use a LC/MS for this sort of thing?

Most organics in water are at a very low concentration, so it is common to have an extraction and concentration procedure to enhance the detection limits of the analytes of interest. Take a look at EPA methods for water analysis to see what methods are used. As the post above notes many of the more solutble organic compounds are polar, and are more suited for analysis by LCMS. You need to define the analyte list you are looking for.The current method you propose is very unlikey to detect very many compounds. The starting temperature on the column is too high and the time before the filament is turned on is too long to detect many of the lighter aromatics. Most of the heavier aromatics will be at such low concentratons that they will not be detected.

Bottom line, define what you are looking for before you develop your method. If you try to develop a method to analyze everything you will probably end up with a method that doesn't work well for a majority of the compounds.

What are your analytes? if they are somewhat volatile, consider using headspace, which eliminates the sample prep and salts and other non-volatile compounds.