Chromatography Forum

Hi

I would like to ask, what method is best for preparing samples for the analysis of Diesel Range Organics in water samples? I am currently using the SPE method and I have learnt that when I run standards straight(without the extraction) the recovery is perfect but once I take a standard of the exact concentration and run it through the extraction method I lose a wholly lot of the diesel constituent.

I tried looking for a different SPE cartridge but so far have not been able to find another kind. No I do not know what to do anymore. I tried to send one of the standards I prepared to another lab to check what the get but they complained about the solvent (propanol) I used for that standard.

Kind regards
Gugu

Complained about propanol? That's about as benign as it gets. I presume you are losing the heavier components in the mix? Have you tried a stronger solvent or a weaker stationary phase? C8 may be all you need to extract those components from the water. You might improve your ability to get them off of the cartridge by using a stronger solvent. Methylene chloride is my preferred solvent for this type of thing. I don't analyze DRO's but I do need to determine FAME's (C16-C22). Works like a charm. Also, CH2Cl2 doesn't burn in the flame very well so your solvent peak is not monstrous.

You can try this: https://sampleprep.unitedchem.com/media ... _8015D.pdf, which worked pretty well in our lab.

Hi

I would like to ask, what method is best for preparing samples for the analysis of Diesel Range Organics in water samples? I am currently using the SPE method and I have learnt that when I run standards straight(without the extraction) the recovery is perfect but once I take a standard of the exact concentration and run it through the extraction method I lose a wholly lot of the diesel constituent.

I tried looking for a different SPE cartridge but so far have not been able to find another kind. No I do not know what to do anymore. I tried to send one of the standards I prepared to another lab to check what the get but they complained about the solvent (propanol) I used for that standard.

Kind regards
Gugu

"rb6banjo
Methylene chloride is my preferred solvent"

Hi yes I do use Methylene Chloride to elute the sample analyte from the cartridge bed, the propanol is for making up my standard with diesel as it is immiscible with water.

Hi X

Thanks i'll take a look at it.

Kind regards
G

We're working with EPA 8015 and extracting DRO/ORO from soils using DCM using EPA3550 without any problems.

Hi

I would like to ask, what method is best for preparing samples for the analysis of Diesel Range Organics in water samples? I am currently using the SPE method and I have learnt that when I run standards straight(without the extraction) the recovery is perfect but once I take a standard of the exact concentration and run it through the extraction method I lose a wholly lot of the diesel constituent.

I tried looking for a different SPE cartridge but so far have not been able to find another kind. No I do not know what to do anymore. I tried to send one of the standards I prepared to another lab to check what the get but they complained about the solvent (propanol) I used for that standard.

Kind regards
Gugu

If you have too much propanol in the sample when you pass it through the SPE cartridge it could be causing some of the DRO to elute when the sample passes through the sorbent. Try making the standard more concentrated so you put less into the water for the same concentration and see if that helps the recovery.

If you are solvent extracting the sample, you shouldn't be doing an SPE extraction on the extracts unless you are trying to do a cleanup.