Chromatography Forum

I'm virtually a complete novice when it comes to GC but am looking for advice as to whether this analytical technique could be viable for this.

Currently I'm running the analysis on LC-UV and have a senstivity of about 10 to 15 ng/mL concentration. We may need a assay that can get down to lower limits. I have tried LC-MS, but it's more noisy than the UV analysis and thus not quite as sesnitive. Could GC-analysis get any lower I wonder.

FYI, presently I'm selectively extracting the dichloro-aniline in a 40% v/v aqueous MeOH. I then overload in LC (100µL on a 15 cm x 0.21 mm) column to achieve the required sensitivity. What would I need to do to adapt to GC analysis (i.e. get rid of water in the extraction process). What starting GC conditions could I use to attain the required sensitivity? Could I just simply use FID or would GC-MS be a more obvious and suitable choice?

As you know I am developing a method for iodo, methylaniline by HPLC.

The manufactures run their C of A impurities check by GC and they see di-iodo as part of their spec so I see no reason di-chloroaniline shouldn't be analysed the same way.

They use a 12m BP10 with a detector temp of 230 deg C
An initial over temp of 80 deg C with a 2 min hold ramping at 10 deg C per min to 240 degC with a 6 minute hold. Injection vol 0.4ul

The di-iodo elutes around 17 minutes on this method.

Apologies on sketchy method details, that is all the manufacturers supplied.

regards, Pat.

Rob - over the years we've assayed 4-chloroaniline and 3,4-dichloroaniline by HPLC both with and without derivatization, HPLC-MS, and GC-electron capture. I'm not sure we approached the limits you desire. Most of this technology is proprietary, so maybe you could detail exactly what and why you're doing this before I'd be able to share more info. If you'd like to discuss by private E-mail, post your E-mail address or post that you can't and maybe I can post mine. I don't know if this board has a private message section.

Hi consumer, could you perhaps post your email, I'm not to sure of our privacy policy here. Cheers

Presently a limit of less than 10 ppb of chloroaniline is possible using SPME with a Polyacrylate fiber. p-Nitroaniline has a similar response. This will be improved when the new PEG fiber from Supelco will be released soon.

Extraction time is 30min direct immersion with agitation from a phosphate buffer pH=9 with 25% NaCl.

The fiber holder is part number 57330-U and the fiber is 57304 (85µm).

Another fiber PDMS-DVB, part number 57326-U, should also perform well.

This analysis is performed by GC-MS using a Supelco low bleed column, SLB-5MS column 30m 0.25mm ID 0.5µm film.

Rodney George
Senior Research and Development Scientist
Gas Separations Research
Supelco
595 North Harrison Road
Bellefonte, PA 16823

814-359-5737 voice
814-359-5459 fax
rgeorge@sial.com

Rob - E-mail to cussboy@cox.net. Also consider Rodney George's information.