Quantitative surface-enhanced Raman spectroscopy chemical analysis using citrate as an in situ calibrant

Area of Science:

• Analytical Chemistry
• Forensic Science
• Spectroscopy

Background:

• Direct detection of illicit substances is crucial for forensic and toxicological applications.
• Surface-Enhanced Raman Spectroscopy (SERS) offers rapid and sensitive detection of molecules.
• Quantifying low concentrations of analytes using SERS presents challenges.

Purpose of the Study:

• To develop a SERS-based strategy for the accurate quantitation of low concentrations of methamphetamine, cocaine, and papaverine.
• To utilize the citrate capping agent on silver nanoparticles as an in situ standard for quantitation.
• To establish a general model for competitive adsorption of citrate and analytes on nanoparticle surfaces.

Main Methods:

• Developed a SERS analysis strategy for quantitating methamphetamine, cocaine, and papaverine.
• Employed citrate as an in situ standard, leveraging its displacement by analytes.
• Utilized a general model for competitive adsorption and Classical Least Squares (CLS) for spectral analysis.

Main Results:

• Successfully quantified low concentrations of target analytes using SERS.
• Demonstrated that citrate displacement is dependent on analyte concentration.
• Achieved accurate analyte concentration determination by extracting SERS contributions of coexisting species.

Conclusions:

• The developed SERS method enables reliable quantitation of illicit substances at low concentrations.
• Citrate serves as an effective local standard for SERS-based analyte quantitation.
• This approach enhances the forensic and toxicological value of SERS analysis.