GC/ECD for cannabis pesticide analysis rather than GC/MS

Discussions about GC and other "gas phase" separation techniques.

9 posts Page 1 of 1
I know quite a few labs are using a GC/MS for the pesticide analysis for cannabis testing but I was wondering if anybody is using a GC with Electron Capture Detection for the GC pesticides. Looking at the action limits for the pesticides, I think an ECD should be able to see those limits no problem.
Hi,
I haven't seen much research into using the ECD but it is possible to use an NPD instead of MS.
Hi I would like to ask if anyone has used HPLC for the analysis of residual pesticides in the water with what procedure, you have also used standards to understand the type of pesticide
pacerlaser wrote:
I know quite a few labs are using a GC/MS for the pesticide analysis for cannabis testing but I was wondering if anybody is using a GC with Electron Capture Detection for the GC pesticides. Looking at the action limits for the pesticides, I think an ECD should be able to see those limits no problem.
Back in the mid 90's I was using ECD for pesticides and PCB's. You need dual columns for confirmation. I was using a DB-1701 and I think the other column was a DB-5. You would need to be sure the list for cannibis analysis are all chlorinated.

Many labs are using HPLC by preference for cannibis pesticides. But I don't know any specifics.
While not specifically for cannabis, EPA method 8081b uses GC/ECD for organohalide pesticides.
I think the only real concern is potential terpene/hydrocarbon interference with the ECD. I asked a sales rep about using the ECD and they (of course) said I needed to use a GC/MS system to achieve the action levels. I think it is funny though that the EPA methods (SW8081B and SW8082A) use ECDs but apparently a GC/MS is needed when it comes to cannabis.
A lot of difference when looking for pesticides in water or soil versus the Quechers method for plant materials. It is difficult to resolve the pesticides from the background noise at the levels needed. Most are using GCMS SIM or LCMSMS to be able to see the levels and eliminate the interferences. Also using GC you would probably need both ECD and NPD to get all the compounds and dual column for confirmation.

For the full list you usually need both GCMS and LCMS since some of the pesticides are more water soluble and some are more soluble in organic solvents.
The past is there to guide us into the future, not to dwell in.
Hello,

I’ve tried multiple methods and instruments. Everything under the top of the line GC-QQQs are cant defect under 0.1ppm.

When it comes to LC it’s almost the same effect. In case of Agilent the 6470 and 6495 are the once to go.

All instruments need a very time intense cleanup step and dilution, dilution, dilution.

Also if you can’t see a see a peak that you spiked and extracted out of a plant sample, your method is not 100% validated. I hear constantly that people are still calibrating neat standards.
adler_LAB wrote:
Hello,

I’ve tried multiple methods and instruments. Everything under the top of the line GC-QQQs are cant defect under 0.1ppm.

When it comes to LC it’s almost the same effect. In case of Agilent the 6470 and 6495 are the once to go.

All instruments need a very time intense cleanup step and dilution, dilution, dilution.

Also if you can’t see a see a peak that you spiked and extracted out of a plant sample, your method is not 100% validated. I hear constantly that people are still calibrating neat standards.


I agree. I am starting on the Oregon list for Hemp Pesticides and am finding most on the list are not good by GC, especially since many are Carbamates. All but a few are working well on LCMSMS as far as detecting in clean standards, but have not began testing with matrix yet. I haven't been able to see MGK-264 on LCMSMS but it works on GCMSMS also Prallethrin and Pyrethrins don't seem to work on the LC. Detection limits for 20ppb by Quechers I think will work for several even on our ABI3200, but for some it may not be possible to go that low.
The past is there to guide us into the future, not to dwell in.
9 posts Page 1 of 1

Who is online

In total there are 8 users online :: 0 registered, 0 hidden and 8 guests (based on users active over the past 5 minutes)
Most users ever online was 599 on Tue Sep 18, 2018 9:27 am

Users browsing this forum: No registered users and 8 guests

Latest Blog Posts from Separation Science

Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.

Subscribe to our eNewsletter with daily, weekly or monthly updates: Food, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.

Liquid Chromatography

Gas Chromatography

Mass Spectrometry