GC/MS Reference standard

[MIB_EO]

Hi
Any suggestions for a quantification reference standard for GC MS?

A 3 day bio-phase reaction is planned. A known concentration of standard to be added at the beginning and its response used to "calibrate" the response of samples after the experiment. This poses a few issues:

It needs to be pH independent.
Soluble in aqueous phase.
Bio-stable (eg not digested by bacteria).
Robust (3 days at 30C, hence less volatile than acetone).

And cheap and commonly available!

Thanks.

[Peter Apps]

"Bio-stability" is the problem since there is no organic compound that some bug or other cannot get its teeth into.

A far as the other requirements are concerned you can take your pick of aldehydes, ketones, esters, alcohols ............

Why do you want to add you analytical standard at the beginning of the process ?, why not follow normal internal standardisation for the analytical step by spiking the samples that you take with a known quantity of i.s. ?

Peter

[MIB_EO]

Thanks we'll try that with Acetone and see how it goes.

[Peter Apps]

Why acetone ? it is inconveniently volatile so you will be losing it at every step of your sample prep, and you are probably not going to be able to separate from any extraction solvents that you use, so it will elute during the solvent delay at the beginning of the run.

It would make sense if you were doing headspace analysis. otherwise go for something with about the same MW as your analyte.

Peter