Acid Attack Prevention: Identification of Acids through a Novel Plastic Container

Importance of the Topic

Acid attacks represent a serious form of violence that has evolved with the use of common plastic containers as delivery devices. Rapid and non‐destructive identification of corrosive agents such as sulfuric and phosphoric acids can aid forensic screening and regulatory control, helping to prevent further incidents and improve public safety.

Objectives and Overview

The main goals of this study were to demonstrate the capability of Raman spectroscopy to:

• Differentiate between strongly corrosive acids and bases.
• Detect acids through the walls of typical plastic squeeze bottles (HDPE/PET).
• Assess sensitivity to acid concentration and protonation states.

Methodology

Samples of eight concentrated acids and bases were first analyzed in glass vials to obtain reference spectra. Phosphoric and sulfuric acids were then introduced into a plastic squeeze lemon container to evaluate through‐plastic detection. Dilutions of polyprotic acids were also prepared to observe spectral changes related to protonation.

Instrumental Setup

The following instrumentation and settings were employed:

• Raman spectrometer: Mira DS
• Laser wavelength: 785 nm
• Attachments: Vial Holder and Long Working Distance (8 mm focal length)
• Software: MiraCal DS 1.0.44
• Integration time: 10 s per spectrum
• Laser power: 5 (arbitrary units)
• Number of averages: 5

Results and Discussion

Distinct Raman signatures were obtained for each acid and base. Spectra collected through the plastic container clearly showed characteristic peaks of both the acid and the plastic polymer (HDPE and PET). Mixture‐matching analysis confirmed simultaneous identification of the container material and the corrosive agent. Protonation‐dependent band shifts in phosphoric acid dilutions highlighted the technique’s sensitivity to chemical speciation.

Benefits and Practical Applications

Raman spectroscopy offers several advantages for acid detection in forensic and security contexts:

• Non‐invasive, through‐plastic analysis without sample removal.
• Rapid spectral acquisition suitable for field screening.
• High specificity for different acids and polymer matrices.

Future Trends and Opportunities

Advances that could enhance this approach include:

• Integration of handheld Raman devices for on‐site screening.
• Development of robust chemometric models for automated identification.
• Expansion of spectral libraries to cover a broader range of corrosives.
• Real‐time monitoring systems in high‐risk locations.

Conclusion

The presented application note demonstrates that Raman spectroscopy, using a Mira DS system, effectively identifies concentrated acids through plastic squeeze bottles. This method supports rapid, non‐destructive detection critical for forensic investigations and preventive regulation of acid attack instruments.

References

Raman Spectroscopy Application Note RS-12, Version 1, February 2019