LC/MS/MS Analysis of Neonicotinoid Pesticides in Dandelion Blossoms on Ascentis^® Express C18 after Dispersive SPE (QuEChERS) using Supel^™ QuE

sample preparation

Dispersive (QuEChERS)

sample/matrix

3 g pulverized dandelion blossoms, homogenized in 10 mL water

extraction tube

Supel QuE Acetate extration tube (55234-U)

extraction process

add 25 mL of acetonitrile; add contents of Supel QuE acetate extraction tube; shake immediately for 1 minute; centrifuge at 3400 rpm for 5 minutes

clean-up tube

Supel QuE PSA/C18 tube (55288-U)

clean-up process

Transfer 1 mL of the acetonitrile layer into a Supel QuE PSA/C18 cleanup tube; shake for 1 minute; centrifuge at 3500 rpm for 3 minutes; (draw off 700 uL 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)

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)

column temp.

25 °C

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

injection

3 μL