LC/MS/MS of Pesticides in Oranges on Ascentis^® Express C18 after Sample Prep using Supel^™ Que Z-Sep/C18 QuEChERS sorbent

sample preparation

Dispersive (QuEChERS)

sample/matrix

10 g of pureed oranges (homogenized with rind); spike at 50 ppb (add 16.75 μL of a custom made pesticide mix, each analyte at 30 μg/mL)

extraction tube

Supel^™ QuE Citrate (EN) Tube (55227-U)

extraction process

add 10 mL acetonitrile; shake for 1 minute; add contents of a Supel QuE citrate extraction tube (55227-U); shake immediately for 1 minute; centrifuge at 3200 rpm for 5 minutes

clean-up tube

Supel-Q PSA/C18 (55284-U)

clean-up process

transfer 0.7 mL of the acetonitrile layer into a Supel QuE Z-Sep/C18 cleanup tube (55284-U); shake for 1 minute; centrifuge at 5000 rpm for 5 minutes; (transfer 0.2 mL of the supernatant into an empty 1.5 mL centrifuge tube; add 0.2 mL of water; centrifuge at 5000 rpm for 2 minutes.)

column

Ascentis Express C18, 5 cm x 2.1 mm I.D., 2.7 μm particles (53822-U)

mobile phase

[A] 10 mM ammonium acetate in water; [B] 10 mM ammonium acetate in acetonitrile

gradient

Hold at 30% B for 1 min; 30% to 80% B in 2 min; hold at 80% B for 4 min; hold at 100% B for 3 min; hold at 30% B for 3 min

flow rate

0.3 mL/min

pressure

2730 psi (188 bar)

column temp.

30 °C

detector

MS/MS, ESI positive