Development and validation of a sensitive LC-MS method for the determination of tramadol in human plasma and urine

A sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS) method was developed and validated for the determination of Tramadol in human plasma and urine. The analyte was separated on a Diamonsil C18 column with ammonium acetate (5 mmol x L(-1))-methanol (50:50,v:v) adjusted PH by caustic soda at a flow rate of 0.8 ml min(-1), and analyzed by mass spectrometry is in positive ion mode. The ion mass spectrum of m/z were 264.1 for Tramadol and 248.0 for Tinidazole (I.S.), respectively. The weighted (1/x2) calibration curve was linear over plasma concentration range 1.00-400.00 ng/ml and urine concentration range 0.01-16.00 microg/ml, with a correlation coefficient (r) of 0.9995 and 0.9997, respectively. The lower limit of quantification in human plasma was 1.00 ng/ml. The inter-and intra-day precisions (CV%) in both plasma and urine were lower than 10%, the mean method accuracies and recoveries from spiked plasma samples at three concentrations ranged from 98.2 to 100.1% and 61.6 to 62.9%, respectively. The developed method was successfully applied to determine Tramadol in human plasma and urine, and provided suitable profiles for clinical pharmacokinetic study of Tramadol.