CCl4 degradation in headspace?
Posted: Thu Jun 08, 2006 8:17 pm
Has anyone experienced carbon tetrachloride degrading to chloroform during headspace sampling?
I'm running both compounds, along with about 20 others, on a DB-WAX column. 21 of the 22 are eluting exactly where they should according to Agilent's data sheet. The exception is CCl4, which is indistinguishable from CHCl3 in my chromatograms. I've injected both a couple of times, and have taken my samples directly from the reagent bottles so as to be sure that I was in fact using the proper solvents.
In a couple of my CCl4 chromatograms (but certainly not all) I've seen a relatively small peak eluting in the approximate time frame where I would expect CCl4 to be. This makes me wonder if, rather than being a chromatographic issue, my CCl4 is actually degrading into CHCl3. I'm using DMI as my diluent, conditioning the sample at 85 C for 25 minutes. There is nothing aside from air, DMI, and CCl4 in my vial. I have noticed that my sample solution becomes somewhat yellowed after either heating or standing overnight.
Has anyone encountered something like this? Do i simply need to find a new diluent?
Thanks.
(EDIT: I don't have easy access to a GC/MS)
(2nd EDIT: I ran in DMF intead of DMI, and the retention time was as it should be. Apparently the DMI causes CCl4 to decompose to CHCl3).
I'm running both compounds, along with about 20 others, on a DB-WAX column. 21 of the 22 are eluting exactly where they should according to Agilent's data sheet. The exception is CCl4, which is indistinguishable from CHCl3 in my chromatograms. I've injected both a couple of times, and have taken my samples directly from the reagent bottles so as to be sure that I was in fact using the proper solvents.
In a couple of my CCl4 chromatograms (but certainly not all) I've seen a relatively small peak eluting in the approximate time frame where I would expect CCl4 to be. This makes me wonder if, rather than being a chromatographic issue, my CCl4 is actually degrading into CHCl3. I'm using DMI as my diluent, conditioning the sample at 85 C for 25 minutes. There is nothing aside from air, DMI, and CCl4 in my vial. I have noticed that my sample solution becomes somewhat yellowed after either heating or standing overnight.
Has anyone encountered something like this? Do i simply need to find a new diluent?
Thanks.
(EDIT: I don't have easy access to a GC/MS)
(2nd EDIT: I ran in DMF intead of DMI, and the retention time was as it should be. Apparently the DMI causes CCl4 to decompose to CHCl3).