Banned and Other Neonicotinoids from Plant Material

Article from Analytix Reporter - Issue 3

QuEChERs Sample cleanup and LC-MS method using a Fused-Core^® particle column complemented by a comprehensive line of reference materials

On Friday, April 27, 2018, representatives of the Member States of the European Union decided to ban the use of three products from the neonicotinoid family of insecticides as they have been deemed dangerous to bees when used on all outdoor crops. Proposed by the European Commission, the text concerns three neonicotinoids (clothianidin, imidacloprid, and thiamethoxam), whose use it had already partially restricted since December 2013. This time, the moratorium was not only expanded, but it was also generalized to include all field crops, leaving only greenhouse use permitted.

The application below demonstrates the extraction and clean up of these banned compounds and others of the neonicotinoid class from dandelion blossoms using the QuEChERS methodology.

For the QuEChERS approach, Supel™ QuE tubes were used for extraction (Acetate) and clean up (PSA/C18) prior to analysis of seven neonicotinoid pesticides. For the LC-MS analysis (Figure 1), an Ascentis^® Express C18 Fused-Core^® particle column was chosen to achieve high efficiency at relatively low back pressure compared to sub-2 micron UHPLC columns.

Figure 1. Separation of Neonicotinoids on Ascentis^® Express C18

Conditions
Sample/matrix	3 g ground dandelion blossoms, homogenized in 10 mL water, spiked at 50ng/g
Extraction process	add 25 mL of acetonitrile; add contents of Supel™ QuE acetate extraction tube (55234-U); shake immediately for 1 min; centrifuge at 3400 rpm for 5 min
Cleanup process	Transfer 1 mL of the acetonitrile layer to Supel™ QuE PSA/C18 cleanup tube (55288-U); shake 1 min.; centrifuge at 3500 rpm for 3 min.; (draw off 700 µL of supernatant, evaporate to dryness at 50 °C under nitrogen; reconstitute in 200 µL of 50:50 0.1% formic acid:0.1% formic acid in methanol)
Column	Ascentis® Express C18, 10 cm x 3.0 mm I.D., 2.7 µm particles (53814-U)
Column temperature	25 °C
Mobile phase	[A] 0.1% formic acid in water; [B] 0.1% formic acid in methanol
Gradient	30% B from 0 to 5 min; to 100% B in 0.2 min; held at 100% B for 5.3 min; to 30% B in 0.5 min; held at 30% B for 5 min
Flow rate	500 µL/min
Pressure	3800 psi (262 bar)
Injection	3 µL
Detector	MS, ESI(+), MRM, m/z 203.2/129.2, 271.2/225.0, 292.1/211.0, 256.0/175.2, 250.0/132.0, 223.2/126.0, 253.0/125.8