Banned and Other Neonicotinoids from Plant Material

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

Banned and other neonicotinoids from plant materialOn 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

Separation of Neonicotinoids

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 temp.: 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

Materials