Chromatography Forum

Can anyone recommend a commercial calibration standard for analysis of petrol?
I will be using GC-FID
My list of target compounds is not finalised but wish to quantitate as many compounds with boiling points less than ~150 (nonane) as possible - without paying too much to make/obtain calibration standards that is.

Thanks
Robt

The usual practice is not to compare to a petrol std for calibration, but to separate as many components as possible and measure each component individually using a 100 meter 100% MS capillary column.

Petrol (Gasoline) is a complex mixture of paraffins, isoparaffins, cycloparaffins, olefins, and aromatics - alkane paraffins, from a possible C3 (winter blend) to around C12. The bulk is C5 to C9 hydrocarbons.

Newer blends reduce or remove olefins and aromatics and add several or more percent of ethanol.

Review the European Union or USA requirements for gasoline and the proper selection of an analysis GC column.

C4, iC4, iC5, C5, MCP, 2,3-DMB, 2,2-DMB, 2-MP, 3-MP, C6, Cyc6, MCH, 2.2-DMP, 2,3-DMP, ECP, 2Me-C6. 3Me-C6, TMP (isooctane) and the homologs in the C8 to C9 range, and C10-12 alkanes are basic markers for a gasoline blend. And of course, ethanol.

good luck finding a calibration blend. But if your system cannot separate the basic components you are wasting your time. Compare with a sample purchased at your local petrol station.

best wishes,

Rod

There are standards for detailed hydrocarbon analysis of petroleum fractions - such as ASTM D-5134. I know that Restek, Accustandard, and Aldrich carry these. They may be listed as PIANO (paraffin, isoparaffin, aromatic, napthalene, olefin) standards or detailed hydrocarbon analysis. These are either mixtures of individual components with specific values for each or some are petroleum fractions with dertificates of analysis. There is a vendor that I ran into back when I was doing some petroleum work - and they seemed (at least back then) to have an intersting range of standards - and if I can come up with the name, I'll post it.

These standards can also be applied to simulated distillation, which is not necesarily interested in a peak by peak analysis of a petroleum fraction.

This website looks familiar - and I think it was the other petroleum standards vendor I used - back then. http://www.spectrumstandards.com/store

Thanks Don, Rod,
The sources you mention do indeed purvey some incredibly complex standard mixtures. I am just concerned that often the product consists of just 100 ul of the mixture and wonder how much service life I will get from a vial with this volume in it. It seems a very small volume to manipulate without fear of fractionation by evaporation. Would these normally be single-use in an industrial setting? (I'm being stingy on this project)

Even more appreciated are your comments about methods - petroleum chemistry being new territory for me - I found what at first seemed a bewildering array of possibilities but have settled on ASTM D6730 - Individual Components in Spark Ignition Engine Fuels by 100–Metre Capillary.

Correction to that last - Spectrum Standards do sell a combined PIANO mix of 2 ml in volume and a PONA mix of 1 ml.
I'd still be interested in your thoughts about handling the 0.1 ml mixtures though.
thanks
Robert

You can purchase the 0.1 mL standards with a valve type closure - which I did. But, I was workign as an applications chemist and showed off how to separate all those compunds well with GCxGC, so I did not worry about the mixtures changing over time. I probably used the standards of a span of 2 - 3 years and the propane and butanes were still in the sampels at reasonable levels (I never did measure relative areas to check it).

But a better bet would be to talke with someone who has a good understanding of the standards. I would expect that someone at Spectrum Standards could give you some guidance. They need to know the standards and their customers - and this is their only line of business...

And by the way - something to dream about for the next revision of your project. More separation of the gasoline. Back when I was at LECO I did the work shown here: http://leco.com/resources/application_n ... 21-254.pdf And if you are careful you can pick out the thiophenes from beside benzene, toluene, and the xylenes. This project was actually a lot of fun!

I would suggest that you determine the RT of each component with the conditions and column you choose and then use a secondary std (an actual sample of petrol) that had been compared to a primary std for any other reference chromatograms you may require.

Most of the paraffins have a very similar response on the FID and most of the aromatics do likewise, but slightly different from the paraffins.

Good luck with your research,

Rod

Rod makes an important point. In my projects with petroleum, I had several jars of gasoline from local stations. I probably ran each of those expenesive standards no more than 5 to 10 times during that long time period - to confirm ID's and to obtain relative response factors (I was using mass spec.)

Wow, that's all very promising for use of the standards and most valuable experience.
Thanks Guys