Employing the CAS Registry (SciFinder-n) to Identify Seized Drugs Using Data from the NIST Hybrid EI Mass Spec Searches

Importance of Topic

Rapid and accurate identification of seized drugs is critical in forensic chemistry for law enforcement, public safety, and public health monitoring. Advanced mass spectrometry databases and registry searches streamline forensic workflows, reducing time to actionable results and improving confidence in substance identification.

Objectives and Study Overview

This work outlines a simplified yet robust strategy for characterizing unknown psychoactive compounds recovered in seizures. It demonstrates how SciFindern (CAS Registry) can be paired with NIST hybrid EI mass spectrometry searches and supporting spectroscopic data to propose and confirm molecular structures effectively.

Methodology and Instrumentation

• Hybrid EI Mass Spectrometry Search: Utilized NIST’s hybrid search algorithm to highlight characteristic substructures, including PCP-related motifs and carbamate functionalities.
• Accurate Mass DART Analysis: Employed Direct Analysis in Real Time (DART) with high-resolution mass spectrometry to determine elemental compositions (e.g., C21H29N, C14H20N2O2).
• Infrared Spectroscopy: Matched functional group absorptions, such as carbamate C=O stretches, to support MS-based hypotheses.
• SciFindern (CAS Registry): Filtered candidates by molecular formula, molecular weight, and registry numbers for rapid structure proposals.
• ChemSpider Comparison: Demonstrated alternative searches using nominal, monoisotopic, and average molecular weight filters.

Main Results and Discussion

• Identification of PCP Analog: The hybrid search suggested a phenylcyclohexylpiperidine substructure, leading to the assignment of phenylcyclohexylpiperidine (PCP, CAS 72241-00-7; C21H29N; MW 295).
• Carbamate-Containing Compound: Mass and IR data indicated a molecule with formula C14H20N2O2 (MW 248). A simple 16 Da oxygen addition (Δmass) was confirmed without requiring external accurate mass calibration.
• Molecular Weight Considerations: Clarified distinctions between average molecular weight, nominal mass, and monoisotopic mass in database searches; highlighted limitations of standard MS data systems for direct molecular weight extraction.
• Elemental Impact on MW: Discussed incremental mass contributions of H and CH2 units, and the pronounced effects of halogen substituents on molecular weight distributions.

Benefits and Practical Applications

• Accelerated Forensic Identification: Combining hybrid MS searches with registry filters narrows down candidate lists quickly.
• Enhanced Confidence: Cross-validation with accurate mass and IR data increases reliability in structural assignments.
• Broad Accessibility: SciFindern’s intuitive interface allows forensic laboratories to adopt the workflow with minimal training.

Future Trends and Potential Uses

• Integration of machine learning for automated substructure and spectral interpretation.
• Expansion of hybrid search capabilities to additional ionization techniques and broader spectral libraries.
• Development of portable MS-DART systems linked to cloud-based registry searches for on-site drug screening.
• Consolidation of multi-modal analytical data (MS, IR, NMR) into unified identification platforms.

Conclusion

Leveraging CAS Registry queries in SciFindern alongside NIST hybrid EI mass spectrometry and infrared spectroscopy offers a streamlined, reliable method for identifying unknown seized drugs. This approach enhances forensic efficiency and can be extended to diverse analytical applications.

Reference

No formal reference list was provided in the source material.