Determination of Heroin in Street Drug Samples

Importance of the topic

Street heroin remains a major public health concern due to its high potency, variable purity and risk of adulteration. Rapid, on-site methods for opioid identification can assist law enforcement, forensic analysts and harm-reduction programs by providing timely information on the presence of heroin in seized materials without extensive laboratory infrastructure.

Study objectives and overview

This white paper reviews the application of Metrohm’s ID Kit in conjunction with the Mira DS handheld Raman analyzer and Printable Surface Enhanced Raman Scattering (P-SERS) substrates for the direct detection of heroin in crude street samples. A secondary goal was to evaluate a range of solvents to determine the optimal extraction medium for maximizing signal clarity, minimizing fluorescence and ensuring compatibility with P-SERS substrates.

Instrumentation used

• ID Kit (Metrohm 607506400)
• Mira DS Raman Analyzer (Metrohm 2.926.0020)
• MiraCal DS Software (Metrohm 606071010)
• SERS Smart Attachment (Metrohm 607506040)

Methodology and instrumentation

Eighteen independent street heroin samples (1–5 mg each) confirmed by GC/MS were extracted in parallel using water, ethanol, methanol, dichloromethane, chloroform, acetonitrile, acetic acid and ethyl acetate. For each trial, 1–2 mg of sample was treated with 250 µL of solvent, vortexed and allowed to settle. A 10 µL aliquot of clear supernatant was deposited onto a P-SERS substrate and air-dried. The substrate was then analyzed in the SERS Smart Attachment of the Mira DS using the following parameters:

• Laser power: 1–3 mW
• Integration time: 0.5–1 s
• Averages: 2
• Raster: off

Main results and discussion

All tested solvents yielded the characteristic heroin Raman peaks at approximately 531, 625 and 1 336 cm–1, but ethyl acetate provided the cleanest spectra with minimal fluorescence and background interference. Classical Raman measurements on crude samples exhibited high fluorescence that obscured target peaks, whereas P-SERS substrates quenched fluorescence effectively, allowing clear heroin identification.

In a blind trial of the 18 street samples, extraction with ethyl acetate followed by P-SERS analysis enabled positive heroin detection in every case. Automated algorithms within MiraCal DS delivered immediate “Opioid ID” readouts on a red hazard screen, streamlining field identification.

Benefits and practical applications

• Rapid on-site detection of heroin without extensive sample preparation
• Minimal sample cleanup using a single solvent extraction
• Suppression of fluorescence interference via P-SERS substrates
• Automated result interpretation for non-specialist users
• Compact, portable instrumentation suitable for field deployment

Future trends and applications

Advancements in portable SERS substrates and automated spectral libraries may broaden detection to other illicit opioids and adulterants. Integration with smartphone-based interfaces and cloud-connected databases could enable real-time monitoring of street drug compositions. Further work on alternative, low-toxicity solvents and miniaturized sample preparation will enhance usability in resource-limited settings.

Conclusion

The combination of Metrohm’s ID Kit, Mira DS Raman analyzer and P-SERS technology offers a fast, reliable and user-friendly approach for the detection of heroin in street samples. Ethyl acetate extraction delivers optimal spectral quality, and automated algorithms provide clear “opioid detected” alerts. This methodology supports frontline drug enforcement and public health initiatives by facilitating rapid chemical screening outside the laboratory.

References

• Metrohm White Paper WP-034EN, January 2021