Waters acquity uplc tqd ms system

About 100 mg (±2 mg) of frozen liver tissue was homogenized after adding 4 mL methanol and 0.85 mL water per gram tissue. The methanol-chloroform method was used to separate the polar metabolites (upper methanol/water phase, contains L-Carnitine) and the lipophilic compounds (lower chloroform phase). Upper layer solvents were removed using a speed vacuum concentrator and under a stream of nitrogen. The samples and standard (Acetyl-d3-L-carnitine, CDN isotopes Quebec) were analyzed on a Waters ACQUITY UPLC TQD MS system (Waters Corp., Milford, MA) equipped with a column heater, sample manager, binary solvent manager, photodiode array eλ (PDA) detector, and ESI source. Samples were separated on an Acquity UPLC BEH HILIC column (100 mm × 2.1 mm (i.d), 1.7 um particle size). The internal standards were detected in positive ion mode with source temperature at 150 °C, desolvation temperature at 400 °C, desolvation gas (N2) flow rate at 700 L/h, and cone gas flow rate at 50 L/h. Capillary voltage was set at 3.5 kV and collision gas flow (Ar) at 0.15 L/h. Dwell time was set at 0.05 s with a span of 0.1 Da. The Cone and collision energy voltage, and MRM mass transitions are summarized in Table 3.