Quantitative analysis of stimulants in whole blood using an evaporation free precipitation salt assisted liquid-liquid extraction (SALLE) sample preparation approach.

Abstract

Purpose: The increasing prevalence of methamphetamine and cocaine in postmortem toxicology casework has placed significant demands on forensic laboratories. This study introduces and validates a streamlined method using salt assisted liquid-liquid extraction (SALLE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to improve the efficiency and reliability of detecting amphetamine-type stimulants (ATS) and cocaine metabolites in forensic toxicology.

Methods: A new SALLE method was developed to analyze a panel of drugs, including amphetamine, methamphetamine, phentermine, 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), pseudoephedrine, cocaine, cocaethylene, and benzoylecgonine (BZE). Calibration models, bias, precision, recovery, matrix effects, interferences, limits of detection (LOD) and quantitation (LOQ), dilution integrity, carryover, and sample stability were evaluated following AAFS standard 036 guidelines. The method was applied to over 150 postmortem and human performance toxicology cases and compared with the traditional gas chromatography-mass spectrometry (GC/MS) approach.

Results: The SALLE-LC-MS/MS method exhibited high accuracy, with all analytes meeting bias and precision criteria (< 20%). Percent recovery values exceeded 80%, while matrix effect values (ion suppression/enhancement) remained below 20%. LODs ranged from 5-25 µg/L, and LOQs ranged from 10-50 µg/L across analytes. Processed samples were stable for up to 8 days. Analysis of 150 cases showed strong agreement with the GC/MS method, with average percent differences ranging from 5.4 to 19.4% for most analytes. The new method reduced sample preparation time by 67% and data-processing time by 80%, resulting in overall time savings of 8 h per batch.

Conclusions: The resulting validated SALLE procedure represents a significant advancement in the analysis of stimulant drugs within forensic toxicology. Its adoption at the Georgia Bureau of Investigation not only addresses current analytical challenges but also sets a precedent for the development of more efficient and reliable methods in the field.