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Commercial Gasoline for calibrating a GRO method?
Posted: Wed Oct 11, 2017 6:19 am
by Gugu
Good day
I would like to ask, has anyone here tried to use commercial gasoline for calibrating a headspace Gasoline Range Organics method (Petrol 93) run on a GC-MS perhaps? If so, what were the results? How stable is it and what solvents did you use and what difficulties did you have?
I use the Bruker Scion SQ GC-MS, with a 5% column.
Kind regards
Gugu
Re: Commercial Gasoline for calibrating a GRO method?
Posted: Wed Oct 11, 2017 6:27 am
by Peter Apps
Gugu
Your main problem is that all the petrol in SA has SASOL synfuel in it, so the composition is quite different to petrol elsewhere.
Peter
Re: Commercial Gasoline for calibrating a GRO method?
Posted: Mon Oct 16, 2017 7:14 am
by Gugu
Gugu
Your main problem is that all the petrol in SA has SASOL synfuel in it, so the composition is quite different to petrol elsewhere.
Peter
Peter
So this would mean it is not ideal for calibration purposes I assume?
Kind regards
Gugu
Re: Commercial Gasoline for calibrating a GRO method?
Posted: Mon Oct 16, 2017 9:02 am
by Peter Apps
Gugu
Your main problem is that all the petrol in SA has SASOL synfuel in it, so the composition is quite different to petrol elsewhere.
Peter
Peter
So this would mean it is not ideal for calibration purposes I assume?
Kind regards
Gugu
You assume correctly. Nothing without a proper certificate of analysis should be used for calibration unless nothing else is available.
Peter
Re: Commercial Gasoline for calibrating a GRO method?
Posted: Thu Oct 19, 2017 3:42 pm
by James_Ball
But if the source of gasoline in the sample is the same as what is available at the pump, then you can more accurately match the standards to the sample. EPA method 8015 suggests that if you know the source of the contamination to use that for the calibration standards if possible.
We always went to the local stations and got a 40ml vial of each fuel(since most stations in town are served by the same vendor) and use that to weigh up a stock standard into methanol. We store both the source and diluted standards in a freezer at -18C. We also purchase a blended composite fuel standard from someone like Restek and compare the two sources, they should agree within the allowances of the methods used(+/-15% for EPA8015).
I like to replace the station gasoline each year, but stored in the freezer I have found each years new compares very well with last years old source, even after a few years it still holds up well.