Determination and quantitation of drugs of abuse and designer opioids in serum

Significance of the Topic

Forensic toxicology requires robust analytical methods capable of detecting a broad spectrum of drugs of abuse, conventional opioids, and emerging designer opioids with high sensitivity and specificity. Rapid metabolism of many substances underscores the need for assays that include both parent compounds and metabolites to extend detection windows. A streamlined workflow using minimal sample volumes is crucial for routine casework such as DUID/DWI investigations, post-mortem analyses, and acute intoxication assessments.

Goals and Study Overview

This study aimed to develop and validate a rapid, reliable UHPLC-MS/MS assay for the simultaneous quantitation of 71 basic drugs, designer opioids, and their metabolites in serum. Key objectives included achieving sub-nanogram-per-milliliter sensitivity, wide calibration range (0.5–250 ng/mL), and excellent accuracy and precision within forensic acceptance criteria.

Methodology

Sample preparation comprised solid phase extraction of 100 µL serum on a Chromabond DRUG cartridge, followed by sequential washing and elution. Extracts were evaporated and reconstituted in 100 µL of mobile phase prior to injection. Calibration standards and quality controls spanned low to high concentration levels to assess linearity, accuracy, precision, and limits of detection.

Instrumentation used

• UHPLC: Bruker Elute system with Solo C18-2 column (100×2.1 mm, 1.8 µm)
• MS/MS: Bruker EVOQ LC-TQ Elite with VIP H-ESI source in positive mode
• MRM optimization: Bruker MRM Builder for transition and collision energy selection

Results and Discussion

The optimized method achieved chromatographic separation of all analytes within 11 minutes. Calibration curves demonstrated strong linearity (R² 0.9901–0.9999). Accuracy bias remained within ±5% for most quality controls, while precision (RSD) was below 5% for over 90% of measurements. Sensitivity was outstanding, with over 75% of analytes exhibiting LODs at or below 0.1 ng/mL. The assay proved robust for routine forensic applications.

Benefits and Practical Applications

The workflow consumes only 100 µL of serum and delivers rapid, high-throughput analysis suitable for a wide range of forensic scenarios. The method’s modular design allows seamless incorporation of additional novel psychoactive substances, prescription or over-the-counter medications via user libraries.

Future Trends and Applications

The platform can evolve through integration of high-resolution mass spectrometry for non-targeted screening, enhanced automation in sample preparation, and data processing aided by machine learning for rapid identification of emerging drug threats.

Conclusion

The developed UHPLC-MS/MS method offers a comprehensive, sensitive, and precise solution for detecting and quantifying classic drugs of abuse and designer opioids in serum. Its speed, low sample requirement, and adaptability make it a valuable asset for forensic toxicology laboratories.

References

Martin R, Kempf J. Determination and quantitation of drugs of abuse and designer opioids in serum. Bruker application note LCMS-159, 2019.