A rapid and reliable method for the quantitation of tricyclic antidepressants in serum using HPLC-MS/MS

Objective: Here we describe a liquid chromatography-tandem mass spectrometry method for the detection of tricyclic antidepressant drugs (amitriptyline, desipramme, imipramine, and nortriptyline) in serum. Design and methods: Following a protein precipitation from serum and dilution of supernatant with water, these analytes and their internal standards (deuterated versions of each drug) were injected, separated, and eluted from a Hypersil Gold C-18 (50 x 2.1 mm) analytical column with a gradient of water and acetonitrile each with 0.1% formic acid. Analytes were then ionized and detected over a 3.5 minute analysis time by electrospray ionization mass spectrometry with multiple reaction monitoring. Matrix effects were characterized using three methods: post-column infusion, pre- and post-extraction addition of analyte to matrix, and comparison of neet to serum preparations. Results: The inter-day and intra-day coefficients of variation for all compounds were <= 12%. The limit of detection for all drugs was < 15 ng/mL and the limit quantitation for all drugs was <22 ng/mL. Recoveries were between 97 and 131% for all drugs. Patient method comparison and proficiency samples were run with acceptable results. Conclusion: We have developed a specific and sensitive method for rapid quantitation of tricyclic antidepressants in serum, suitable for use in the clinical laboratory. (C) 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.