Chromatography Forum

has anyone out there had difficulty recovering aniline and/or 4-chloroaniline from soil using epa method 3550 (ultrasonic extraction with 1:1 acetone/methylene chloride)?

i have worked with epa method 8270 (semivolatile organics by gcms for about 10 years, but only in the past couple of years have i had trouble determining method detection limits for these 2 compounds.

i am spiking 5 µg, and concentrating the extract to 1 mL, which translates to 5 ng on-column. recovery of 4-chloroaniline ~10%, aniline even worse.
a little experimentation seems to have isolated the problem to the concentration step (k-d concentrators on steam bath), and the presence of the acetone in the solvent.

the mdl spike mix contains about 75 compounds, none of which has presented a problem before, other than benzidine, which usually disappears even at much higher spiking levels. most compounds work at 2.5 ng on-column, though i have to fortify the mix to 5 or 10 ng for a few of the phenols, anilines, hexachlorocyclopentadiene, benzidines.

i tried spiking each of these 2 compounds by themselves at 10 times higher concentration. this resulted in ~60% recovery, and the c-gram seemed to show a trace of a possible reaction product (ms spectrum did not yield a good library match.)

thanks for any insight regarding this puzzle!

I have problems with anilines especially aniline and 4-chloroaniline. I have about 10ng on-column and extract via tumbling in DCM/acetone followed by KD concentrating.

I have always thought that the losses were due to active sites in the GC , as we get better recovery after clipping the column/cleaning the inlet andI find the inlet liners can greatly affect recovery. I sometimes get up to 3 times more or less recovery depending on who prepped the liners!

I have had the same problem. I found the the preservatif use in the dichloromethane could ruin an extraction for aniline and 3-chloroaniline.

One of the industry leading GCMS systems has been know to have problems with some nitrogen containing aromatics. Do you have the same low response on pure standards, or does the problem only show up after extractions? if the response is good on the unextracted standards but bad on the extracted the extraction is the problem, if the response is low on both the problem is in the GCMS system.