Determination of Tramadol by Capillary GC-FID and a study of postmortem distribution in rats

Abstract

A rapid, precise and accurate capillary gas chromatographic assay with flame ionization detection (GC-FID) was developed for the determination of tramadol (TMD) in biological samples. It is comprised of liquid extraction procedure with mixture (2:3, V dichloromethane /V ether ) at pH 11.15 and gas chromatography with SHIMADZU GC-14C. The recoveries of TMD and SKF 525A (internal standard) were in the range of 98.5-106.2% and at an average of 103.8%. Calibration graphs were linear over the concentration range of 5.0-400.0 μg/mL and 5.0-400.0 μg/g with coefficient of variation as (0.9-3.1% (within-day) and 1.4-5.5% (between-days)). The limits of detection were 0.01 μg/mL in plasma and urine and 0.01 μg/g in liver based on signal- to-noise ratio of 3. We also investigated the distribution of TMD in acute poisoned rats after oral administration at 1140 mg/kg of TMD (5×LD 50 ), and determined the average concentration in heart blood, peripheral blood, urine, vitreous humor, heart, lung, liver, spleen, kidney and brain, respectively. We concluded that the concentration of TMD in heart blood and liver is much higher compared to other body fluids and organs. Thus, blood and urine are suitable samples for forensic toxicological analysis. This developing analysis method and postmortem-distribution study can be potentially useful in forensic drug testing.