Internal standard optimization advances sensitivity and robustness of ratiometric detection method.

Area of Science:

• Analytical Chemistry
• Environmental Science
• Materials Science

Background:

• Nitrite ions are crucial environmental indicators, but their accurate determination in complex matrices like lake water remains challenging.
• Surface-enhanced Raman scattering (SERS) offers high sensitivity for chemical detection, but traditional methods can be limited by matrix effects and signal stability.

Purpose of the Study:

• To develop a highly sensitive and reliable ratiometric SERS method for quantifying nitrite ions in lake water.
• To investigate the transformation of p-aminothiophenol (pATP) to p,p'-dimercaptoazobenzene (DMAB) triggered by nitrite ions as a detection mechanism.
• To enhance detection sensitivity by utilizing a novel internal standard in the SERS spectrum.

Main Methods:

• Fabrication of a p-aminothiophenol (pATP) modified gold/indium tin oxide (Au/ITO) chip.
• Utilizing the nitrite-induced chemical transformation of pATP to p,p'-dimercaptoazobenzene (DMAB) for signal generation.
• Employing a ratiometric SERS approach with a novel internal standard (SERS peak at 1008 cm⁻¹) for improved accuracy and sensitivity.

Main Results:

• The pATP-modified Au/ITO chip successfully detected nitrite ions in lake water samples.
• Nitrite ions triggered the expected transformation of pATP to DMAB, generating a measurable SERS signal.
• Using the 1008 cm⁻¹ SERS peak as an internal standard improved detection sensitivity by 10 times compared to traditional methods.

Conclusions:

• The developed ratiometric SERS method provides a sensitive and effective approach for determining nitrite ions in environmental water samples.
• The novel internal standard strategy significantly enhances the reliability and sensitivity of SERS-based nitrite detection.
• This method holds promise for environmental monitoring applications requiring precise nitrite ion quantification.