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.

Automated and High-Throughput Urine Drug Screening Using Paper Spray Mass Spectrometry

Paper spray mass spectrometry (PS-MS) has been shown to be a rapid, simple and inexpensive alternative to traditional forensic drug screening methods. It can address the limitations of both immunoassays and chromatography-based techniques due to its non-reliance on sample preparation and its ability to rapidly screen for a wide array of compounds. In this study, an automated PS-MS system was employed to semi-quantitatively screen for 40 commonly abused drugs and metabolites in urine after a 15-min glucuronidase reaction. The target compounds included common prescription opioids, fentanyl and norfentanyl, stimulants including methamphetamine and cocaine, benzodiazepines and antidepressants. The enzyme, buffer and internal standard solution were combined in one spiking solution to minimize sample handling. Analysis was carried out using a commercially available automated paper spray system coupled to a triple quadrupole mass spectrometer. This method may prove useful for clinical and forensic toxicology laboratories as it allows for automated screening of complex samples for drugs without extraction, separation and sample cleanup.

Stability and Hydrolysis of Desomorphine-Glucuronide

Desomorphine, the principal opioid in Krokodil, has an analgesic potency approximately ten-times that of morphine. Similar to other opioids, during phase II metabolism it undergoes conjugation with glucuronic acid to form desomorphine-glucuronide. Although hydrolysis of conjugated species is sometimes required prior to analysis, desomorphine-glucuronide has not been fully investigated. In this study, six hydrolysis procedures were optimized and evaluated. Deconjugation efficiencies using chemical and enzymatic hydrolysis were evaluated and stability in aqueous solution was assessed. Acid hydrolysis was compared with five β-glucuronidase sources (BGTurbo™, IMCSzyme™, Escherichia coli, Helix pomatia and Patella vulgata). At optimal conditions, each hydrolysis method produced complete hydrolysis (≥96%). However, under simulated challenging conditions, P. vulgata was the most efficient β-glucuronidase for the hydrolysis of desomorphine-glucuronide. Both BGTurbo™ and IMCSzyme™ offered fast hydrolysis with no need for sample cleanup prior to liquid chromatography-quadrupole/time of flight-mass spectrometry (LC-Q/TOF-MS) analysis. Hydrolysates using E. coli, H. pomatia and P. vulgata underwent additional sample treatment using β-Gone™ cartridges. Additionally, the stability of free and conjugated drug was evaluated at elevated temperature (60°C) in aqueous solutions between pH 4 and 10. No degradation was observed for either desomorphine or desomorphine-glucuronide under any of the conditions tested.

Analytical Considerations When Developing an LC-MS/MS Method for More than 30 Analytes

BACKGROUND

While validation of analytical (LC-MS/MS) methods has been documented in any number of articles and reference texts, the optimal design and subsequent validation of a method for over 30 analytes presents special challenges. Conventional approaches to calibration curves, controls, and run time are not tenable in such methods. This report details the practical aspects of designing and implementing such a method in accordance with College of American Pathologists validation criteria.

METHODS

Conventional criteria were followed in the design and validation of a method for 34 analytes and 15 internal standards by LC-MS/MS. These criteria are laid out in a standard operating procedure, which is followed without exception and is consistent with College of American Pathologists criteria.

RESULTS

The method presented herein provides quality results and accurate medication monitoring. The method was optimized to negate interferences (both from within the method and from potential concomitant compounds), increase throughput, and provide reproducible quality quantification over relevant analyte concentrations ranges.

CONCLUSIONS

The method was designed primarily with quality and accurate medication monitoring in mind. The method achieves these goals by use of novel approaches to calibration curves and controls that both improve performance and minimize risk (financial and operational). As automation and LC-MS/MS equipment continue to improve, it is expected that more methods like this one will be developed.