Chromatography Forum

Do any of you know any method of analyzing glycols (3 of them) by GC-FID
I have soil samples. Please can anyone help me. Also i was wondering if i can do headspace analysis on soils but i dont know what matrix to mix the soil sample with. Please can anyone help me or guide me to a link for some methods. Thank you in advance

I found a method online from the US EPA:

https://www2.gov.bc.ca/assets/gov/envir ... nload=true

If you can't read that, it basically takes the soil, extracts it with water, filters out the solids and shoots the water directly into the GC.

If it were me, I'd probably do something similar but I'd pass the aqueous soil sample through a reversed phase SPE cartridge to get rid of the soil. It's not likely the glycols will be retained by the SPE packing.

I made a good living extracting glycols and similar compounds from consumer products with DMF or pyridine, then adding BSTFA as the silylation agent. Silylation was practically instantaneous. GC or GCMS on nonpolar capillary; there are publications dealing with this.

I found a method online from the US EPA:

https://www2.gov.bc.ca/assets/gov/envir ... nload=true

If you can't read that, it basically takes the soil, extracts it with water, filters out the solids and shoots the water directly into the GC.

If it were me, I'd probably do something similar but I'd pass the aqueous soil sample through a reversed phase SPE cartridge to get rid of the soil. It's not likely the glycols will be retained by the SPE packing.

Is headspace possible because I don't like injecting liquid into the GC. Headspace increases the life of the GC. If I were to do headspace what solvent will I mix the soil with and the vial what solvent to put inside at what matrix.

The water extraction of soils will that work in glycols or any other compounds.

What temperature of column and the ramp in the GC would work? Thank you for all your help again

What limit of detection do you need in your analysis?

I have had success with propylene glycol and headspace analysis but the detection limit is fairly high (on the order of low 10's of parts-per-million, µg/mL) as I recall. It's been a while since I did this. I used solid-phase microextraction to do the headspace sampling and a wax column as the stationary phase. I've never tried EG or any other glycols for that matter.

I was looking for coolant leaking from a heat exchanger in my application so this detection limit was good for me. Adding salt to the water may help improve the LOD but you'll have to use SPME to have even a small chance. I fear that static headspace sampling fail. Glycols are just too water soluble to get much up into the headspace.

I was never able to get head space to work for water samples.
Direct injection of water does work, but you need to take into consideration water's expansion volume.

Ok so I guess I wont use head space then for glycol.

The samples are water and soil,
So if I do direct injection of soil extract. What solvent will I use to extract the soil without getting rid of glycols.
Do you guys have GC-FID method for analyzing soils, water
How to ramp, column temperature etc. Thank you

For glycols I do a 1:1 addition of soil:DI water to a VOA vial and sonicate the closed vial. I centrifuge the vial and transfer a 1mL aliquot of the water to a 7673 injection vial for analysis. I add 5uL internals and surrogates after capping the vial. A 1uL injection of water has a vapor volume sufficient to completely fill the inlet volume.

My guess is that headspace would not work for the same reason glycols purge poorly. They have too high a boiling point.

For glycols I do a 1:1 addition of soil:DI water to a VOA vial and sonicate the closed vial. I centrifuge the vial and transfer a 1mL aliquot of the water to a 7673 injection vial for analysis. I add 5uL internals and surrogates after capping the vial. A 1uL injection of water has a vapor volume sufficient to completely fill the inlet volume.

My guess is that headspace would not work for the same reason glycols purge poorly. They have too high a boiling point.

If i do direct injection of water containing glycols in FID is it a good idea or not. OR mix the water with standards and then inject

How did you prepare your glycol standards. Which stock solution you used to create it from? thank you

If i do direct injection of water containing glycols in FID is it a good idea or not. OR mix the water with standards and then inject

How did you prepare your glycol standards. Which stock solution you used to create it from? thank you

I found that 1uL of water would put out my 5890 GC-FID. I don't know how you can reliably get around that. It may work better with a 6890 GC-FID setup but I have not tried that. So, I ran my methanol and glycols by 5890/5971 GC-MS. I diluted straight P&T grade methanol, Fisher certified plus 2-propanol, Fisher Sci Certified Ethylene Glycol and 1,2 propane diol (oil fields use that for dewatering natural gas) for my standard curves. I used 1,2-Dimethoxyethane as an IS for the alcohols and Ethylene Glycol Butyl Ether as an IS for the Glycols. I used AccuStandard alcohol and glycol standards to verify the calibration curve. I was using a 20m 0.20mm DB-624 with 5m of 0.53mm DB-WAX inserted as a pre/guard column. This was back in 2013 and I was trying to figure out how to hold back the alcohols for better resolution and the DB-WAX section was to improve peak shape, move the chromatogram peaks out of the water peak and keep the flashed water volume from overwhelming the inlet.

Let me say, my methanol and glycol methods are very crude; developed to deal with oilfield brines. I would very much like to hear how this is done in a certified lab by someone with more experience.

If i do direct injection of water containing glycols in FID is it a good idea or not. OR mix the water with standards and then inject

How did you prepare your glycol standards. Which stock solution you used to create it from? thank you

I found that 1uL of water would put out my 5890 GC-FID. I don't know how you can reliably get around that. It may work better with a 6890 GC-FID setup but I have not tried that. So, I ran my methanol and glycols by 5890/5971 GC-MS. I diluted straight P&T grade methanol, Fisher certified plus 2-propanol, Fisher Sci Certified Ethylene Glycol and 1,2 propane diol (oil fields use that for dewatering natural gas) for my standard curves. I used 1,2-Dimethoxyethane as an IS for the alcohols and Ethylene Glycol Butyl Ether as an IS for the Glycols. I used AccuStandard alcohol and glycol standards to verify the calibration curve. I was using a 20m 0.20mm DB-624 with 5m of 0.53mm DB-WAX inserted as a pre/guard column. This was back in 2013 and I was trying to figure out how to hold back the alcohols for better resolution and the DB-WAX section was to improve peak shape, move the chromatogram peaks out of the water peak and keep the flashed water volume from overwhelming the inlet.

Let me say, my methanol and glycol methods are very crude; developed to deal with oilfield brines. I would very much like to hear how this is done in a certified lab by someone with more experience.

thank you very much for your help

just one last thing. The current sample i have are clean water with glycols inside. So i ordered a 50000ug/ml standard with 2 components matrix is water. I also want to order a calibration check standard accustandard has only 1 component inside. Do you have any idea where to find standard with components more than 1 and the matrix is water

I don't know of a vendor that has certified multiple glycols standard in a water matrix. List which glycols you trying to analyze and maybe someone will chime in with a vendor. Also, you can ask your favorite vendor to give you a quote for a custom mix.

If i do direct injection of water containing glycols in FID is it a good idea or not. OR mix the water with standards and then inject

How did you prepare your glycol standards. Which stock solution you used to create it from? thank you

I found that 1uL of water would put out my 5890 GC-FID. I don't know how you can reliably get around that. It may work better with a 6890 GC-FID setup but I have not tried that. So, I ran my methanol and glycols by 5890/5971 GC-MS. I diluted straight P&T grade methanol, Fisher certified plus 2-propanol, Fisher Sci Certified Ethylene Glycol and 1,2 propane diol (oil fields use that for dewatering natural gas) for my standard curves. I used 1,2-Dimethoxyethane as an IS for the alcohols and Ethylene Glycol Butyl Ether as an IS for the Glycols. I used AccuStandard alcohol and glycol standards to verify the calibration curve. I was using a 20m 0.20mm DB-624 with 5m of 0.53mm DB-WAX inserted as a pre/guard column. This was back in 2013 and I was trying to figure out how to hold back the alcohols for better resolution and the DB-WAX section was to improve peak shape, move the chromatogram peaks out of the water peak and keep the flashed water volume from overwhelming the inlet.

Let me say, my methanol and glycol methods are very crude; developed to deal with oilfield brines. I would very much like to hear how this is done in a certified lab by someone with more experience.

thank you very much for your help

just one last thing. The current sample i have are clean water with glycols inside. So i ordered a 50000ug/ml standard with 2 components matrix is water. I also want to order a calibration check standard accustandard has only 1 component inside. Do you have any idea where to find standard with components more than 1 and the matrix is water

Is that the Restek mix? I see they have that mix(ethylene and propylene) on their website, if not look there for a second mix.

We have always just direct injected water samples and used the 5g to 5ml DI Water for soil extraction then filter and shoot. I was able to get our old 5890 to stay lit long ago when doing it but I think I had to adjust either the H2 or Air to make it work. It was also on a 0.53ID column so it was a very narrow band when it passed through and the carrier flow was Helium at about 7ml/min. if I remember correctly, it has been a very long time since I did that.

I found that 1uL of water would put out my 5890 GC-FID. I don't know how you can reliably get around that. It may work better with a 6890 GC-FID setup but I have not tried that. So, I ran my methanol and glycols by 5890/5971 GC-MS. I diluted straight P&T grade methanol, Fisher certified plus 2-propanol, Fisher Sci Certified Ethylene Glycol and 1,2 propane diol (oil fields use that for dewatering natural gas) for my standard curves. I used 1,2-Dimethoxyethane as an IS for the alcohols and Ethylene Glycol Butyl Ether as an IS for the Glycols. I used AccuStandard alcohol and glycol standards to verify the calibration curve. I was using a 20m 0.20mm DB-624 with 5m of 0.53mm DB-WAX inserted as a pre/guard column. This was back in 2013 and I was trying to figure out how to hold back the alcohols for better resolution and the DB-WAX section was to improve peak shape, move the chromatogram peaks out of the water peak and keep the flashed water volume from overwhelming the inlet.

Let me say, my methanol and glycol methods are very crude; developed to deal with oilfield brines. I would very much like to hear how this is done in a certified lab by someone with more experience.

thank you very much for your help

just one last thing. The current sample i have are clean water with glycols inside. So i ordered a 50000ug/ml standard with 2 components matrix is water. I also want to order a calibration check standard accustandard has only 1 component inside. Do you have any idea where to find standard with components more than 1 and the matrix is water

Is that the Restek mix? I see they have that mix(ethylene and propylene) on their website, if not look there for a second mix.

We have always just direct injected water samples and used the 5g to 5ml DI Water for soil extraction then filter and shoot. I was able to get our old 5890 to stay lit long ago when doing it but I think I had to adjust either the H2 or Air to make it work. It was also on a 0.53ID column so it was a very narrow band when it passed through and the carrier flow was Helium at about 7ml/min. if I remember correctly, it has been a very long time since I did that.

Thank you very much for your help i really appreciate it

Sorry so late in the game. Why not headspace. No liquid added. Or if you really want to add a liquid, why not something heavy like DMSO (might be too polar...) Why not just total evaporation? I can dig for notes in headspace book if you insist.

Second, wanna keep an HP FID lit? Put an auxilliary heater on the chimney. Agilent base may be 300 but you can probably still paw the chimney. Works for everything else because you burn at the jet but water does not burn. ... which is why you get corrosion in the chimney....

Best regards,

AICMM