Diazotization-coupling reaction-based selective determination of nitrite in complex samples using shell-isolated...

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Nanotechnology

Background:

• Nitrite ion determination is crucial in various fields, including food safety and environmental monitoring.
• Existing methods for nitrite detection can be complex or lack selectivity.
• Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) offers high sensitivity for molecular detection.

Purpose of the Study:

• To develop a simple, rapid, and selective method for nitrite ion determination.
• To utilize the diazotization-coupling reaction coupled with SHINERS for indirect nitrite detection.
• To evaluate the method's performance in complex real-world samples.

Main Methods:

• Developed a SHINERS active substrate using gold nanoparticles with a porous silica shell.
• Employed a diazotization-coupling reaction to convert nitrite into a SHINERS-active azo dye.
• Investigated factors influencing reaction kinetics and SHINERS signal intensity.

Main Results:

• Achieved linear detection of nitrite in the range of 0.5-6.0 mg L⁻¹ with high correlation coefficients (r² > 0.9793).
• Demonstrated low relative standard deviations (<14.5%) for replicate measurements.
• Obtained low limits of detection (0.07-0.10 mg L⁻¹) without sample preconcentration.

Conclusions:

• The developed SHINERS method provides a sensitive, selective, and rapid approach for indirect nitrite determination.
• The method shows great potential for trace analysis of nitrite in diverse complex samples like food, biological, and environmental matrices.
• This protocol is adaptable for the indirect detection of other compounds with weak Raman signals, such as iodate, phenols, and aromatic amines.