Agilent eclipse plus c18 rrhd

Quantitation of 14 in plasma, CSF, and brain homogenate by LC-MS/MS was performed as previously described.^{47 (link)} Briefly, 14 was extracted from plasma, CSF, and brain samples with methanol containing glutamate-d₅ (10 μM ISTD) by vortexing followed by centrifugation 16000g for 5 min. Supernatants were aliquoted and dried at 45 °C for under vacuum for 1 h. Sodium bicarbonate buffer (0.2M, pH 9.0) and dabsyl chloride (10 mM) in acetone were added to each tube, mixed, and incubated for 15 min at 60 °C to derivatize. Samples were then injected and separated on an Agilent 1290 equipped with an Agilent Eclipse plus C18 RRHD 2.1 mm × 100 mm column over a 2.5 min gradient from 20 to 95% acetonitrile +0.1% formic acid and quantified on an Agilent 6520 QTOF mass spectrometer. Peak area ratio of the analyte to the internal standard was plotted against a 14 standard curve to yield 14 concentrations for each sample.