An investigation into the potential use of liquid chromatography:mass spectrometry in forensic toxicology
The aim of this project was to evaluate the use of LC-MS in the forensic toxicology setting. To investigate if its use could solve problems encountered while using other instrumentation including downtime, limits of detection, chromatography and specificity. Benzodiazepines as a class, are known for their undesirable chromatographic behaviour when using GC. Using LC-MS two models were developed for the analysis of these drugs in whole blood. Increasing awareness of drug facilitated sexual assault, has led to an increase in the number of cases to be analysed for drugs such as Rohypnol®. This prompted the development and validation of a sensitive and specific method for its detection in blood using solid phase extraction and liquid chromatography – mass spectrometry. To enhance the qualitative data and cope with degraded samples, the use of LC-MS was used in the analysis of diazepam and its three metabolites. A method was developed and validated and is now used in the routine analysis of blood samples in the laboratory. The LC-MS proved invaluable in the analysis of sildenafil, Viagra®, in a post-mortem blood sample received in the laboratory. A single quadrupole mass spectrometer was used to develop and validate a method to determine if the dose was therapeutic or toxic. The use of oral fluid as an alternative specimen to blood or urine was investigated. This was through the British Roadside Impairment Test Evaluation (BRITE) project. LC-MS in combination with GC-MS was used to screen for over 50 licit and illicit drugs in 1mL of oral fluid. LC-MS-MS was then used to identify and quantitated 21 drugs of abuse and their metabolites using a similar sample size. The use of one extraction and the reliability of LC-MS proved invaluable in these projects.