Chromatography Forum

Hello, I'd like to know if someone of you do fire debris analysis. I'd like to share some experiences about that kind of analysis and ask for some recommendations. Have a good day everybody.

1. Have you had some issues with cans? (in case that you use ASTM E1412) I detect dichlorobenzene in a sample blank, I found out dichlorobenzene is in the can along with toluene, ethylbenzene and xylenes.

2. We use toluene and perchloroethylene (internal standard) for a kind of verification for GM/MS prior the use of this equipment. Have you use other compounds?

3. We use CS2 for desorbing the compounds in carbon strip. Have you used other solvent? I read CS2 is the best solvent for this task.

4. What temperature do you use for heating cans before use them for real samples?

Thank you very much for your comments.

I haven't done air sampling before but since toluene is such a major component in gasoline I would use toluene-d8 instead as the internal standard so that you don't have to worry about it possibly contaminating your samples. The deuterated version should not be found in normal samples.

Are you talking about headspace analysis?

If so, then yes, using SPME with a carboxen based fibre, which works well in this type of investigation

. We use CS2 for desorbing the compounds in carbon strip. Have you used other solvent? I read CS2 is the best solvent for this task.

Yes, CS2 for desorbing BTEX from activated carbon tubes

1. Have you had some issues with cans? (in case that you use ASTM E1412) I detect dichlorobenzene in a sample blank, I found out dichlorobenzene is in the can along with toluene, ethylbenzene and xylenes.

Some cans contain ignitable liquids that are components of the epoxy used to line the can walls. Gold-lined cans are known for this in particular. You will have to experiment with different linings until you find one with a negligible background. Alternatively, use unlined cans.

2. We use toluene and perchloroethylene (internal standard) for a kind of verification for GM/MS prior the use of this equipment. Have you use other compounds?

Keep in mind that toluene is a component of many ignitable liquids and will disrupt the concentrations of toluene present in any of your samples. And don't forget that toluene is an ignitable liquid in and of itself. I would find another compound (touene-D8 works well, as suggested), or just stick to PCE.

3. We use CS2 for desorbing the compounds in carbon strip. Have you used other solvent? I read CS2 is the best solvent for this task.

CS2 is the most efficient solvent in terms of pure desorbing power. But it's highly toxic, so use at your own risk. There has been plenty of research into the pros and cons of various solvents for this purpose - check Stauffer's book for a comprehensive discussion.

4. What temperature do you use for heating cans before use them for real samples?

That depends on the background present in the cans from manufacture. Heat them at a temperature high enough to burn off any contaminants. You'll have to experiment to find the sweet spot.