Chromatography Forum

Hi

I am currently trying to get an appropriate or relevant EPA method for analysing THMs with the Bruker Scion SQ GC-MS, from which I can develop a method that suits the 5% column I am using. Does anybody know where I can get a method like that other than the EPA 501.3 method?

Sincerely
Gugu

Hi

I am currently trying to get an appropriate or relevant EPA method for analysing THMs with the Bruker Scion SQ GC-MS, from which I can develop a method that suits the 5% column I am using. Does anybody know where I can get a method like that other than the EPA 501.3 method?

Sincerely
Gugu

All EPA methods are available online. What do you think about 524.3 ?
What's wrong with 501.3 ?
BTW - DB-5 column resolves all THMs perfectly

"All EPA methods are available online. What do you think about 524.3 ?
What's wrong with 501.3 ?
BTW - DB-5 column resolves all THMs perfectly"

Was looking at the 501.3 method with a Bruker product specialist and he says the column specified on the method sets everything off even though our method was modified to suit our needs according to the column I am using, on which I run four other methods by the way. Hence, that may give us problems for accreditation purposes.

I had not checked method 524.3, thanks will do just now.

Gugu

"Was looking at the 501.3 method with a Bruker product specialist and he says the column specified on the method sets everything off even though our method was modified to suit our needs according to the column I am using, on which I run four other methods by the way. Hence, that may give us problems for accreditation purposes. "

The paragraph 5.10.1 of the method 501.3 says: "Other
columns may be used if they provide data with adequate accuracy and
precision as specified in this method."

As you can see you don't need to be affraid of using DB-5 column instead of phased out packed columns form old 501.3 method.

What column exactly do you use ?
I anticipated capillary DB-5, but you didn't confirmed.

What column exactly do you use ?
I anticipated capillary DB-5, but you didn't confirmed.

Sorry about that, Rxi-5Sil MS, 30m, 0.25mmID and 0.25 um df. max temp is 350 degrees and min is 320 degrees.

What column exactly do you use ?
I anticipated capillary DB-5, but you didn't confirmed.

Sorry about that, Rxi-5Sil MS, 30m, 0.25mmID and 0.25 um df. max temp is 350 degrees and min is 320 degrees.

It's DB-5 equivalent. It won't resolve all VOCs, but will resolve all THMs. 30 m is enough but film thickness may be to low.

It's DB-5 equivalent. It won't resolve all VOCs, but will resolve all THMs. 30 m is enough but film thickness may be to low.[/quote]

Oh okay thanks a lot I will look into it.

Rxi-5SilMS is equivalent to DB-5MS, they are both silarylene columns.
DB-5 is equivalent to HP-5 and Rtx-5.

The first two columns are slighty different than standard 5% phenyl and they may exhibit different separation on some compounds.

Probably they won't affect VOCs, they are usually SVOCs specific.

0.25 µm film thickness on 0.25 mm ID column should be O.K. for VOCs.
Good luck and let us know about the progress.

Are you doing the extraction with Pentane? If so you have to look really hard to find Pentane that does not have traces of Chloroform. We did the 501 method for years and that was our most difficult problem.

If you are using purge and trap that isn't so much of a problem, which is why we run 524.2 and moving to 524.3 for the THMs.

For THMs now I run the Rxi-624SilMS column. The max temperature is 320C which makes it compatible with the oven temperatures of the Rxi5SilMS columns so I actually have both in the GC at the same time, and join them together before going into the MS so I can run all the Volatiles and Semivolatiles on one instrument, Purge and Trap connected to the 624 column and the 5 column is in a Split/Splitless injection port.