|SOFT - TIAFT 1998||Poster Session 4||Friday October 9, 1998|
AUTOMATED ANALYSIS OF CONTROLLED DRUGS IN BIOLOGICAL SAMPLES|
Bridin Brady, John Corish, Siobhán Moane* and Liam Regan
State Laboratory, Dublin 15, Ireland.
|Existing state-of-the-art confirmatory GC-MS techniques for drugs of abuse such as heroin, ecstacy and cocaine in blood and urine consist of sample preparation which is complicated and time-consuming, especially when the number of samples is large. It involves sample purification to eliminate endogenous compounds, followed by analyte pre-concentration by solid-phase extraction (SPE) and derivatisation prior to injection onto the GC-MS system. Automation of the SPE procedure greatly speeds up analysis, thereby increasing sample throughput and improving reproducibility of results.
The work reported here has successfully automated the existing manual opiate SPE method using a Gilson Automated Sample Preparation with Extraction Cartridges (ASPEC XL) system. The method extracts morphine, codeine, dihydrocodeine and the main metabolite of heroin, 6-monoacetylmorphine (6-MAM), from blood and urine using mixed-mode IST Confirm HCX cartridges. Following off-line derivatisation, the samples are separated by capillary GC and detected by an ion-trap MS in electron ionisation mode. Quantitation is based on peak area ratios of analyte to deuterated internal standards, from calibration curves in the range 0.25-5.0 µg/ml morphine, codeine and dihydrocodeine and 0.05-1.0 µg/ml 6-MAM for urine analysis and 0.05-1.0 µg/ml morphine, codeine and dihydrocodeine and 0.01-0.2 µg/ml 6-MAM for blood analysis.
The method has been optimised and evaluated, with limits of detection of 0.05 µg/ml for the four drugs in both blood and urine, based on a signal-to-noise ratio of 3:1. Recoveries of morphine, codeine, dihydrocodeine and 6 -MAM from blood were 59%, 58%, 57% and 56%, respectively. Recoveries from urine were 87%, 87%, 91% and 58%, respectively. Good correlation was obtained between real samples determined by the manual and automated methods.