by
LALman » Tue Feb 13, 2018 10:56 pm
sohaib1 wrote:
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.