Surface-enhanced Raman scattering spectroscopy of explosive 2,4-dinitroanisole using modified silver nanoparticles

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• 2,4-Dinitroanisole (DNAN) is a less sensitive explosive alternative to 2,4,6-trinitrotoluene (TNT).
• Sensitive detection methods for explosives like DNAN are crucial for safety and security.
• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity for molecular detection.

Purpose of the Study:

• To develop and optimize a SERS method for detecting 2,4-dinitroanisole (DNAN).
• To investigate the mechanism of SERS detection of DNAN using modified silver nanoparticles (AgNPs).
• To evaluate the influence of common water constituents on DNAN detection sensitivity.

Main Methods:

• SERS analysis of DNAN using AgNPs modified with L-cysteine methyl ester hydrochloride.
• Comparative study using different L-cysteine derivatives as modifiers to elucidate the SERS mechanism.
• Investigation of the impact of various anions and cations on DNAN SERS signals.

Main Results:

• Modified AgNPs achieved sensitive detection of DNAN down to 20 μg/L in deionized water and 0.1 mg/L in aged tap water.
• The amino group of L-cysteine methyl ester hydrochloride was identified as the active site, with the methyl ester group enhancing sensitivity.
• Certain ions (SO(4)(2-), Na(+), Mg(2+), Ca(2+)) quenched DNAN SERS signals, while others (CO(3)(2-), Cl(-), K(+)) did not significantly interfere.
• Sulfate ions could mitigate the quenching effect of divalent cations.

Conclusions:

• L-cysteine methyl ester hydrochloride-modified AgNPs provide a sensitive SERS platform for DNAN detection.
• The detection mechanism involves Meisenheimer complex formation, influenced by the modifier's chemical structure.
• Understanding the effects of water matrix components is essential for practical SERS applications in environmental or security contexts.