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low pesticide limits with GC/MS
Posted: Mon Aug 27, 2018 9:20 pm
by promeo01
Has anyone had success getting pesticide detection limits to .01 ppm using GC-MS (like the Agilent 5973)?
We are looking at etridiazole or PCNB or fenthion at .01 ppm and want to see if we can use a GC/MS (instead of GC/MS/MS triple quad). The gc/ms is significantly less expensive than a triple quad MS.
Re: low pesticide limits with GC/MS
Posted: Thu Aug 30, 2018 7:49 am
by AaronAIT
I can't speak for those particular pesticides, but I have been impressed with the sensitivity of the new Agilent 5977B with the High Efficiency Source. Maybe see if Agilent can do a demo for you with some of your samples or standards.
Re: low pesticide limits with GC/MS
Posted: Wed Sep 12, 2018 2:41 pm
by James_Ball
I have run several analytes at those levels, just not those specific pesticides, but you will probably want to use SIM mode to see them well. There are also techniques like CSR-LVSI, (concurrent solvent recondensation–large volume splitless injection) that works well for these types of analytes.
http://www.restek.com/Technical-Resourc ... /ev_an1331
https://blog.restek.com/?p=620
Select a retention gap/guard column with a polarity that matches your solvent, that is the only thing that really can mess with the ability to do the injections that large. I was using a 0.25ID retention gap with a 0.18ID analytical column and only doing about 25ul injections and it worked well.
Re: low pesticide limits with GC/MS
Posted: Wed Sep 19, 2018 5:42 pm
by James_Ball
I can't speak for those particular pesticides, but I have been impressed with the sensitivity of the new Agilent 5977B with the High Efficiency Source. Maybe see if Agilent can do a demo for you with some of your samples or standards.
Do you have experience with the High Efficiency Source? I have been wondering about those since we are looking to purchase our first 5977 and was trying to decide if I should go for that or just the extractor source similar to what is in the 7000C I have. I know they are much more sensitive but do they have much linear range and are they stable? Doesn't to me any good if I can't calibrate over a factor of 20 (0.1-50ppm or similar) range or if they get dirty quickly since I will be analyzing mostly dirty, oily waste, waste water, and soils on the new instrument.
Re: low pesticide limits with GC/MS
Posted: Mon Sep 24, 2018 7:52 am
by AaronAIT
James - I'll send you a PM now.
edit - anyone know how to send PMs on here?
Re: low pesticide limits with GC/MS
Posted: Mon Sep 24, 2018 4:29 pm
by James_Ball
James - I'll send you a PM now.
edit - anyone know how to send PMs on here?
I believe they are disabled on the site.
you can send it to my first initial dot last name at mccoylabs dot com and it should come through.