Table 3 The LC–MS/MS conditions

LC

Equipment: ekspert microLC 200 (eksigent)

Column: Shim-pack GIST NH2 (75 mm × 1 mm, 3 µm) for 5FU and GEM

Mobile phase: A: 0.1% (v/v) formic acid in water

B: Acetonitrile

Isocratic elution: A 2%, B 98%

Flow rate: 50 µL/min

Column temperature: 30℃

Injection volume: 2 µL

MS

Equipment: QTRAP 5500 (AB Sciex)

Ion Source: Turbo spray

Ionization: Electrospray ionization

Curtain gas: 30 psi

Collision gas: High

Ion spray voltage: -4500 V (5FU), 4500 V (GEM)

Temperature: 300℃

Measurement mode: Multiple reaction monitoring