Oasis hlb 1cc 10 mg extraction cartridge

The samples were extracted by solid phase extraction (SPE) on Oasis HLB 1cc (10 mg) extraction cartridge (Waters, Milford, MA, USA). The extraction cartridge was conditioned with 2 mL of methanol followed by 1 mL of distilled water. The sample (900 µL) was then loaded into the cartridge and washed with 1 mL of 0.1% (v/v) aqueous formic acid. Finally, 1 mL of methanol was used as an eluting solvent, and the elute was reconstituted in 1 mL of distilled water. An aliquot (3 μL) was injected onto the LC-MS/MS.

For LC-MS/MS sample preparation, 100 µL plasma was mixed with 20 µL 50% methanol and 200 µL 4% phosphoric acid. Whole sample mixtures were added to an Oasis HLB 1 cc/10 mg extraction cartridge (Waters, MA, USA) equilibrated with 1 mL methanol and 1 mL distilled water. The column was washed with 1 mL 5% methanol and eluted with 1 mL methanol. The eluate was dried under nitrogen flow and dissolved in 100 µL solvent A/B (30%:70%, v/v) for LC-MS/MS. 10 µL samples were analyzed by a Waters LC-MS/MS unit. ACQUITY UPLC BEH HILIC, 1.7 µm, 2.1 mm I.D. × 100 mm (Milford, MA, USA), was used at a flow rate of 0.3 mL/min by linear gradient elution (solvent A: solvent B = 30%:70%, v/v; solvent A: 0.1% TFA, solvent B: acetonitrile) using electro-spray ionization for Xevo TQ MS (Waters).

For sample preparation, 100 μL plasma was mixed with 20 μL 50% methanol and 200 μL 4% phosphoric acid. Whole sample mixture was added to the Oasis HLB 1 cc/10 mg extraction cartridge (Waters) equilibrated with 1 mL methanol and 1 mL distilled water. The column was washed with 1 mL 5% methanol and eluted with 1 mL methanol. The elute was dried under nitrogen flow and dissolved in 100 μL solvent A/B (30% : 70%, v/v) for LC-MS/MS. 10 μL sample was analyzed by a Waters LC-MS/MS unit; ACQUITY UPLC BEH HILIC, 1.7 μm, 2.1 mm I.D. × 100 mm (Milford, MA) was used at a flow rate of 0.3 mL/min by linear gradient elution (solvent A : solvent B = 30% : 70%, v/v, solvent A: 0.1% TFA, solvent B: acetonitrile) using electrospray ionization for Xevo TQ MS (Waters, MA, USA).