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Herbicide Preperation

Posted: Wed Jan 17, 2018 10:18 pm
by madewald
Hello,

We have a new LC/MS/MS in the lab and have worked out the instrumentation part of things but the sample preparation is eluding us right now. We would like to run herbicides and pesticides from ground water sources. Does anyone have a good place to start looking or better yet an extraction method that they would be willing to share?

Any help would be greatly appreciated.

Re: Herbicide Preperation

Posted: Thu Jan 18, 2018 3:39 am
by HPLC chemist
Check the EPA for methods, then the Waters, Phenomenex, and Agilent websites.

Re: Herbicide Preperation

Posted: Thu Jan 18, 2018 7:38 am
by Rndirk
In addition to HPLC chemist response, if your instrument is new the supplier should be happy to help in getting you started (hands-on) with whatever method you want to run.

Re: Herbicide Preperation

Posted: Thu Jan 18, 2018 7:25 pm
by James_Ball
What matrix are you testing?

If food or food products look into QUECHERS, extractions. Just search that and you will find tons of information on it.

I do know that on LCMS you can analyze the herbicides without the need to dirivatize like you do on GC-GCMS.

Re: Herbicide Preperation

Posted: Thu Jan 18, 2018 7:39 pm
by madewald
We are looking at groundwater samples from aquifers and surface water.

Re: Herbicide Preperation

Posted: Fri Jan 19, 2018 5:00 pm
by James_Ball
For that you would be looking at either liquid/liquid extraction or solid phase extraction.

EPA 515, 508 and 507 are extraction methods for GC, but you would need to exchange the final solvent for something LC compatible.

Check with Restek, Supoelco or UCT and see if they have Solid Phase Extraction methods listed, also Phenomenex might have SPE methods also.

Re: Herbicide Preperation

Posted: Fri Jan 19, 2018 8:15 pm
by Rndirk
Recent instruments can detect pesticides down to ppt level for 1-10µL injections. I would definitely consider the option of no sample prep for your ground water samples, as this is a clean matrix. In practice, you filter and inject. Optional steps are dilution and addition of internal standards. Always, as in every method, use the divert valve.

Quechers works well for water samples too, if you want to keep the method short and simple. The pH of the water will have to be adjusted to protonate the most acidic compound you want to measure, else the recovery will be low.