Enhancement of Raman intensity for the detection of fentanyl

Significance of the topic

Fentanyl is a synthetic opioid approximately 100 times more potent than morphine and 50 times more potent than heroin. Illicit use and overdoses have become a major public health crisis, creating the need for rapid and sensitive detection methods.

Aims and study overview

This application note presents the development of an electrochemical surface-enhanced Raman spectroscopy (EC-SERS) method using screen-printed electrodes for the rapid screening of fentanyl at trace concentrations.

Methodology

The protocol involves in situ electrochemical activation of gold (220BT) or silver (C013) screen-printed electrodes to generate plasmonic nanostructures, followed by SERS detection of fentanyl. Cyclic voltammetry was performed: gold SPE scans from +0.70 V to +1.40 V and back to –0.20 V in 0.1 M KCl at 0.05 V/s; silver SPE scans from 0.00 V to +0.40 V and back to –0.40 V in 0.1 M HClO4 with 0.01 M KCl at the same rate.

Used instrumentation

• SPELEC Raman instrument (785 nm laser)
• 785 nm Raman probe
• Raman spectroelectrochemical cell for SPEs
• Gold SPE (220BT) and Silver SPE (C013)
• Connection cable for SPEs
• DropView SPELEC spectroelectrochemical software

Main results and discussion

The method successfully detected fentanyl on both Au and Ag electrodes, with a prominent Raman band at ~1000 cm–1 serving as an analytical marker. Vibrational mode assignments showed electrode-dependent shifts. Calibration on gold SPE demonstrated a linear response for fentanyl concentrations from 1×10–6 M (0.33 µg/mL) to 1×10–5 M (3.37 µg/mL) with R2 = 0.997.

Benefits and practical applications

This EC-SERS approach offers a rapid, sensitive, and cost-effective tool for on-site fentanyl screening in forensic and clinical settings, requiring minimal sample preparation and leveraging portable SPEs.

Future trends and applications

Advancements may include optimized nanostructured substrates for enhanced sensitivity, multiplexed detection of opioid mixtures, integration into portable devices, and application of machine learning for automated spectral analysis.

Conclusion

The combined EC-SERS method on screen-printed electrodes provides a fast and reproducible protocol for micromolar fentanyl detection in a single experiment, demonstrating strong potential for field-deployable drug screening.

References

1. Ott C.E. et al. Forensic Identification of Fentanyl and Its Analogs by Electrochemical-Surface Enhanced Raman Spectroscopy (EC-SERS) for the Screening of Seized Drugs of Abuse. Front. Anal. Sci. 2022;2.
2. Wang L., Deriu C., Wu W. et al. Surface Enhanced Raman Spectroscopy, Raman, and Density Functional Theoretical Analyses of Fentanyl and Six Analogs. J. Raman Spectrosc. 2019;50(10):1405–1415.
3. Leonard J., Haddad A., Green O. et al. SERS, Raman, and DFT Analyses of Fentanyl and Carfentanil: Toward Detection of Trace Samples. J. Raman Spectrosc. 2017;48(10):1323–1329.