Determination of tramadol in human serum by capillary gas chromatography with nitrogen-selective detection

A specific, sensitive and precise method for the determination of tramadol in human serum is described. It comprises a three-step extraction procedure and a specific determination by capillary gas chromatography with nitrogen-selective detection, using a homologue of tramadol as an internal standard. The specificity of the method was checked by gas chromatography-mass spectrometry. Precision parameters were 1.7-5.5% (within-run) and 3.2-5.7% (between-run) in the concentration range 12.5-200 ng/ml. The detection limit was about 3 ng/ml.