The measurement of plasma melatonin levels by high performance liquid chromatography

Objective: We aimed to establish high performance liquid chromatography (HPLC) method to measure plasma melatonin levels easily, sensitively and reliably. Methods: We used fluorescence detection, 75 mM sodium acetate/acetonitrile (72/28, v/v)(pH 5) as a mobile phase, isocratic method, 275 and 345 nm excitation and emission wavelengths, respectively. Samples were extracted using solid phase extraction column (Waters Oasis HLB 1 cc cartridge). Results: The recovery was found as 97.2%. Inter-assay and intra-assay coefficients of variation (CV) were 4.02% and 5.41%, respectively. Detection limit was 0.25 pg/mL and linear range was up to 1000 pg/mL. Conclusion: These findings suggest that our method is suitable to measure plasma melatonin levels.