by
Zoraku » Wed Apr 24, 2019 2:56 pm
PhysisGC wrote:
Hello All,
I am supposed to be working on neonicotinoids (imidacloprid, dinotefuran, imidacloprid, thiacloprid, thiamethoxam, clothianidin) by GC/MS but am having trouble with low response. I have also had an issue finding articles detailing methods by GC, most seem to be using an LC/MS.
I have 3 Aginlent 7890s each equipped with 5975C, 5977A, and 7000 MS/MS. I am considering NCI or derivatization but without some guidance its just a shot in the dark.
Does anyone have any experience with these compounds on a GC?
We will eventually need to extract these compounds out of water with a DCM shakeout if anyone has tips on that too.
I had to come up with an identity test for imidacloprid on GC/MS, so I'll be happy to share the methodology:
Sample solvent: Acetonitrile
Oven Program: 50ºC for 2min then ramp to 250ºC at 10ºC/min and hold for 5min then ramp to 325ºC at 10ºC/min and hold for 10min
Run time: 44.5min
Inlet temperature: 325ºC
Injection volume: 1uL
Split flow: 100mL/min
Flow velocity: Helium at 45cm/s
Column: Agilent HP-5ms: 30m x 250um x 0.25um
MSD Transfer line: 335ºC
MS Source: 230ºC
MS Quad: 150ºC
Solvent delay: 5min
My sample concentration was roughly 0.75mg/mL. I never did any quantification of Imidacloprid via GC/MS but it's clear that these parameters provide the ability to detect it. Your mileage may vary on recovery or the ability to quantify, but this might be a good starting point for you. Hopefully this helps.
Here are some chromatograms of the formulation with and without Imidacloprid present so you can see that it does in fact show up:
Here is our imidacloprid standard:
Here is the formulation:
Here is the blank of my formulation and as you can see it is missing the peak at 20.2min where Imidacloprid was shown found.
*Edit for grammar/typo*