Chromatography Forum

Hello!

I am trying to develop a method to analyze propylene glycol using purge&trap with GC/MS. I have tried it with up to 10ppm standard, but still cannot extract ion 45 (major ion according to NIST MS) from the chromatogram. I know there are methods for FID, but client wants only GC/MS for compliance reasons. I would have tried direct inject, but for obvious reasons the matrix is WATER.

Is it possible to extract in an organic solvent and then inject? or is my best option just purge and trap?

Any help is greatly appreciated!!
THANKS!

Hi
You can try with headspace. I think you can see 10ppm.
I detected it in HS-GC-FID.

Tª incubation.- 70ºC
t incubation.- 30 min (with agitation)
add 20% of NACl to the sample

If you're trying to extend one of the USEPA's purge and trap methods to propylene glycol, it will be pretty difficult due to the combination of very low volatility and water solubility.

I have fairly commonly seen it showing up in the extractables (625 or 8270) side of things, though I have not done any spiking studies to see what type of recovery achievable.

Greg

Water injections are usually not a problem on modern bonded phase columns. The only thing you really need to worry about is turning on the filaments after the water has passed through the column, not before.

As a point of interest, most purge and trap systems, even with water managment, transfer approximately 1 uL of water to the GC during the desorb, so going to purge and trap does not eliminate water.

We do ethylene and propylene glycol in serum by derivatizing with phenylboronic acid. Works well, with good quantitative data. DL is a couple of ppm, I believe.

We do ethylene and propylene glycol in serum by derivatizing with phenylboronic acid. Works well, with good quantitative data. DL is a couple of ppm, I believe.

Is this a headspace application? Are the derivatized glycols less likely to have carry over issues? I need to analyze Ethylene Glycol, Diethylene Glycol and have ran into carry over issues.

We do ethylene and propylene glycol in serum by derivatizing with phenylboronic acid. Works well, with good quantitative data. DL is a couple of ppm, I believe.

Is this a headspace application? Are the derivatized glycols less likely to have carry over issues? I need to analyze Ethylene Glycol, Diethylene Glycol and have ran into carry over issues.

This is not a headspace method. We combine 100 µL of serum with 700 µL of acetonitrile, 100 µL of dimethoxypropane, and 100 µL of 2 mg/mL phenylboronic acid. Standards are made by spiking control serum and running it through the method. Analysis is by GC/MS. We have only had problems with carryover when levels are very high (which they can be in instances of glycol poisoning). Unfortunately, I don't think this method would work for diethylene glycol.

While the step from GC-FID to GC-MS is nice because of abilty to confirm, there is a got-ya in the exchange. You typically have a lower limit of detection with an FID. So if you are pushing the limit with GC-FID or are even close to it, then you are less likely to succed with GC-MS. -- OK, a tripple quad might get the sensitivity back, but it costs a bit more.

I would suggest spiking heavily to find the peak and then back down to see how low you can go. Also, do you have any system checks to be sure the headspace sampler is working correctly with the GC? (I hate spending a week beating my head against the wall looking for sensitivity - and discovering a loose fitting or such )

Hi
You can try with headspace. I think you can see 10ppm.
I detected it in HS-GC-FID.

Tª incubation.- 70ºC
t incubation.- 30 min (with agitation)
add 20% of NACl to the sample

Hi Francesc,

I am currently trying to analyze ethylene glycol as a residual solvent in API, by means of HS-GC-FID as well. Could you provide me more details of your method? (kind of column, GC temperature ramp, etc.)
On the other hand, which is the purpose of adding NaCl?

Thank you very much in advance
Regards,

jotapee

USP monograph for glycerin has a trace level ethylene glycol assay.

Thanks for your quick feed-back CPG

I've just printed and had a look to this method. It looks nice, but the point is that I wanted to avoid direct GC injection and use GC-HS, because my sample matrix dirties the glassliner in just a couple of injections, so I'm fearing huge problems during method validation... and also complaints from QC department for its daily use

Thanks for your quick feed-back CPG

I've just printed and had a look to this method. It looks nice, but the point is that I wanted to avoid direct GC injection and use GC-HS, because my sample matrix dirties the glassliner in just a couple of injections, so I'm fearing huge problems during method validation... and also complaints from QC department for its daily use

Hi again,

This desperate cromatographist has found a method from Perkin-Elmer (Determination of Ethylene Glycol in Used Engine Oil by Headspace-Gas Chromatography) that looked very simple and promising (derivatisation on vial with phenylboronic acid).
I've similarly tried this afternoon the derivatisation with PBA in this way: a HS vial filled with 5 mg and a solution of 620 ppm ethylene glycol in DMF (ICH limit as you know), but I have observed only the same peaks than in the blank solution with 5 mg PBA and DMF. Does anyone have experience to tell me what I'm missing? I've read in other posts in the ChromForum that you may need a basic catalyst but nothing more in detail...


jotapee