Chromatography Forum

I have kind of a general question for anyone running 525.2. Everytime I run samples it seems like there is some thing different that goes wrong. I was wondering if anyone experiences headaches with this method or if maybe it's just me??

525.2 is a peculiar method...i've run the entire gammut, from phthalate contamination to poor endrin breakdown to analytes disapearing... only to show up again in the next lfb.
1. clean the inlet
2. use focus liner
3. I exctract and concentrate in as low light as possible
4. muffle EVERYTHING!!! anything glass should be washed and muffled, even if you opened a brand new box... really it works.
5. I let the water and meoh sit on the column for about 20 min. prior to starting the extract...then i let the 1:1 EtoAc:DCM set for 20 min during elution...that has seemed to bump up recoveries on some problem compounds.
alot of the people on this forum are great resources...

hope this helps some.

Baking out in the miffle furnace I will have to try, I have been baking in a regular oven.

My only concern with letting the extract sit that long is if I'm in a crunch for time and need analysis relativly quickly my normal QC and "samples" will probably have very different recoveries. In the last audit we had the auditor was a little concerned about my recoveries jumping all over the place, but the tunes did not indicate a leak and the responses were all with in range. Any idea what could be causing that? I extract useing a 6 disk station manual manifold, so usually most samples are extracted at the same time.

I use the chromabond c18 6/1000 glass cartridge and my responses are pretty stable... The discs gave me nothing but grief, some people swear by them, i took them to the shooting range. the reason i let the eluent sit on the column is to allow it enough time to "interact" with the stationary phase...it has helped my recoveries.