Determination of Drugs of Abuse in Hair by UPLC-MS/MS: View from Brazil

Significance of the Topic

Human hair testing provides a unique and non-invasive means to monitor drug exposure over extended periods. Unlike blood or urine, hair analysis can reconstruct a chronological history of substance use and supports large-scale screening within forensic and regulatory frameworks. In Brazil, hair testing underpins the issuance of commercial driving licenses, driving the need for rapid, reliable assays.

Objectives and Overview of the Study

The primary objective was to develop and validate a robust UPLC-MS/MS method for the simultaneous quantification of a panel of drugs of abuse and key metabolites in hair. The method was intended to meet the confirmation cut-offs recommended by the Society of Hair Testing and to support a testing volume exceeding one million samples per year.

Methodology and Instrumentation

Sample Preparation:

• Collection of control and real hair samples from volunteers.
• Methanol decontamination followed by cutting into 1–2 mm segments.
• Spiking with deuterated internal standards at 0.4 ng/mg when available.
• Incubation of 10 mg hair in methanol at 50 °C for 15 hours after pulverization.
• Centrifugation and direct transfer of supernatant into Total Recovery vial.

Chromatography and Detection:

• ACQUITY UPLC I-Class FTN system with BEH C18 column (1.7 µm, p/n 186002349).
• Gradient elution using formic acid and acetonitrile.
• Run time of 1.2 minutes for target analytes; 5.5 minutes for carboxy-THC confirmatory assay.
• Xevo TQ-S micro mass spectrometer monitoring at least two MRM transitions per analyte.

Main Results and Discussion

The method achieved baseline separation of all analytes, including isobaric norcocaine and benzoylecgonine, within 1.2 minutes. Quantification was linear over the validation ranges, exemplified by THC calibration from 0.02 to 0.3 ng/mg with acceptable residuals. Sensitivity met or exceeded Society of Hair Testing confirmation thresholds, demonstrating precision and reproducibility suitable for routine high-throughput workflows.

Benefits and Practical Applications

• High sample throughput with total analysis time under 1.3 minutes per injection.
• Non-invasive collection and stable long-term storage of hair samples.
• Compliance with international confirmation criteria for forensic toxicology.
• Scalable to support over one million tests annually for driving license programs.

Future Trends and Applications

Advances may include expanded multiplex panels covering emerging psychoactive substances, automated sample preparation modules, and segmental hair analysis for detailed exposure timelines. Integration with digital reporting platforms will further streamline forensic and clinical applications.

Conclusion

The combination of the ACQUITY UPLC I-Class FTN system and Xevo TQ-S micro mass spectrometer delivers a rapid, sensitive, and robust platform for hair-based drug screening. This approach meets the demands of large-scale forensic testing and regulatory compliance with high confidence and efficiency.

References

• Cooper G. A. A.; Kronstrand R.; Kintz P. Society of Hair Testing Guidelines for Drug Testing in Hair. Forensic Science International 2012, 218, 20–24.