Automated enzymatic hydrolysis of urine samples for improved systematic toxicological analysis of drug-facilitated sexual assault cases

Drug-facilitated sexual assault (DFSA) is characterized by victim incapacitation due to intoxicating substances. Detection of single drug exposure from DFSA requires a systematic toxicological analysis strategy including sensitive methods covering a broad spectrum of substances. The aim of this study was to develop and validate an UHPLC–MS/MS screening method for analysis of samples from DFSA cases and incorporate an automated enzymatic pre-treatment of urine samples into a robotic sample preparation for an efficient laboratory workflow. The screening method included 144 drugs of abuse, pharmaceuticals, and metabolites relevant to DFSA. The use of a recombinant enzyme showed an efficient glucuronide hydrolysis with an average parent drug recovery of 97%. Investigation of matrix effect showed no pronounced ion enhancement or suppression for most analytes (96%), and extraction recovery was above 80% for 97% of analytes. Process efficiency ranged from 50% to 138% for most analytes. The LODs ranged from 0.0001 mg/L to 2 mg/L depending on analyte, and most analytes met the SOFT recommended minimum performance limits. The validated method was applied to authentic suspected DFSA cases (n = 38). Results showed that drugs of abuse, benzodiazepines, and antidepressants were most commonly found in suspected DFSA cases. Incorporation of an automated enzymatic hydrolysis step during sample preparation enables a fast and simple workflow for simultaneous analysis of blood and urine samples for an improved systematic toxicological analysis strategy for DFSA cases.