To highlight the importance of simultaneous quantitation of commonly encountered drugs (lidocaine, orphenadrine, chlorpheniramine and chloroquine) in biological specimens (blood, urine, and liver) using GC-MS technique.

Introduction: quantitation of drugs is of paramount importance in forensic toxicology. It plays a decisive role in establishing the cause of death by determining the therapeutic, toxic or lethal range of drugs in biological specimens. This presentation will provide an insight into the simultaneous quantitation of drugs in blood, urine, and liver in a short time using the dispersive solid phase extraction method. In recent years, the author's lab has seen an increase in the number of cases with a history of overdose of commonly used therapeutic drugs and wrong injections. To address the high influx of cases and backlog situation, there was a need to quantitate the drugs simultaneously with a short run time.

The extraction was performed using the modified QuEChERS method. QuEChERS method for extraction of these drugs from biological specimens has already been developed and validated. The separation was achieved on GC-MS (Agilent-7890A/5975, capillary column DB-5, 15m×250μm×0.25μm, split less, run time 14.75min, scan mode) using helium as carrier gas. Brucine was used as an internal standard. Screening of biological specimens on GC-MS indicated the presence of orphenadrine, lidocaine, chlorpheniramine and chloroquine in three different cases. The Selected Ion Monitoring (SIM) mode was used for the quantitation of these analytes in respective case samples.

The quantitated amount of lidocaine in liver in case No.1 was 10.25mg/kg. The quantitated amounts of chloroquine and chlorpheniramine in liver in case No.2 were 19.93mg/kg and 0.95mg/Kg respectively. The quantitated amounts of orphenadrine and chlorpheniramine in blood in case No.3 were 1.35mg/L and 0.13mg/L respectively. The quantitated amounts of orphenadrine and chlorpheniramine in urine in case No.3 were 5.51mg/L and 0.47mg/L respectively.

The current method demonstrated a good linearity range (r2) above 0.985 from 100 to 1000μg/L. The limit of detection (LOD) and limit of quantitation (LOQ) were 100μg/L for all the analytes. No interference from the matrices was observed and samples remained stable for 12hours in the GC-MS ALS. The developed method is robust and reproducible which employed the dispersive solid phase extraction procedure with a recovery above 90% for all the analytes.

This method has been successfully used for the quantitation of the above mentioned drugs in routine cases. The goal of this research was to simultaneously analyze orphenadrine, lidocaine, chlorpheniramine and chloroquine in blood, urine, and liver samples using GC-MS technique. This research is highly important in forensic toxicology labs in establishing the therapeutic, toxic and lethal range of these therapeutically used drugs. The current method is quick, easy, cheap and reproducible.