Determination of tramadol in hair using solid phase extraction and GC–MS

Tramadol is a centrally acting synthetic analgesic with μ-opioid receptor agonist activity, it is a widely prescribed analgesic used in the treatment of moderate to severe pain and as an alternative to opiates. Tramadol causes less respiratory depression than morphine at recommended doses. Its efficacy and low incidence of side effects lead to its unnecessary prescribing in patients with mild pain. Tramadol was classified as a “controlled drug” long after its approval for use in Jordan. Analysis of drugs of abuse in hair has been used in routine forensic toxicology as an alternative to blood in studying addiction history of drug abusers. A method for the determination of tramadol in hair using solid phase extraction and gas chromatography–mass spectrometry (GC–MS) is presented, the method offers excellent precision (3.5–9.8%, (M)=6.77%), accuracy (6.9–12%, M=9.4%) and limit of detection 0.5 ng/mg. The recovery was in the range of 87–94.3% with an average of 90.75%. The calibration curve was linear over the concentration range 0.5–5.0 ng/mg hair with correlation coefficient of 0.998. The developed method was tested on 11 hair samples taken from patients using tramadol as prescribed by their physician along with other different drugs in treating chronic illnesses. Tramadol was detected in all hair samples at a concentration of 0.176–16.3 ng/mg with mean concentration of 4.41 ng/mg. The developed method has the potential of being applied in forensic drug hair testing. In Jordan, hair drug testing started to draw the attention of legal authorities which stimulated forensic toxicologists in recent years to develop methods of analysis of drugs known or have the potential to be abused.