Standardized Methods Specifically for C1-C5

[segaloco]

Hey all, I've got a methodology question. Does anyone know if there are any standardized methods (EPA, ASTM, ISO, ANSI, etc) specifically for the analysis and quantitation of C1-C5 by FID? I don't need to get real specific, so no necessary speciation of C4, C5, etc but I do need to tell pretty well where C4 stops and C5 starts, etc. Basically the application here is as a screening instrument for GC/IRMS analysis later on down the road, to determine not only the concentration of methane so that we don't overload the detector, but also the ratios of C1 to C2, C3, and so on. The end intent here is a number of metrics on the light-end hydrocarbon footprint of air and water samples for a variety of applications, such as geological studies, air/water quality, etc. It doesn't have to be a certifiable method, as this is used for research data only, but the more controlled and well tested the better. Thank you for any suggestions!

By the way, methods proven somewhat effective with headspace sampling are best, as that's how we are sampling for the GC/IRMS, but I'm open to suggestions, as we have a purge-and-trap concentrator at our disposal too. My main concerns with just winging it trying to develop my own method is that I'm not quite sure how to ensure that only alkanes are making it into the mix, I'm afraid I'm gonna end up with alcohols, ketones, etc all over the place. Again, any help is greatly appreciated!

[Steve Reimer]

RSK-175 comes to mind. It is not an approved method but has been cited for fracking wastewater.

[segaloco]

Thank you, I also came across ASTM 1945, which is just about what I want, but I'd probably substitute an FID for the TCD, that should eliminate some extraneous stuff, and maybe some tweaks to the oven ramp to cut it off after C5 resolves.