Borate interference in surface-enhanced Raman spectroscopy of amines

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Surface-enhanced Raman (SER) spectroscopy is a powerful technique for analyzing analytes.
• Borate ions can interfere with SER spectra, especially for basic analytes.
• Silver colloids are common substrates for SER, but their preparation and surface chemistry are critical.

Purpose of the Study:

• To investigate the interference of borate in SER spectra of basic analytes.
• To understand the factors influencing borate adsorption and spectral interference.
• To explore strategies for mitigating borate interference in SER analysis.

Main Methods:

• Preparation of borohydride-reduced silver colloids.
• Acquisition of SER spectra for lysine and propylamine.
• Analysis of spectral band intensities in relation to pH, surface oxidation, and analyte adsorptivity.

Main Results:

• Borate bands were observed in SER spectra of lysine and propylamine, and other basic analytes.
• Analyte and borate band intensities were dependent on colloid pH, surface oxidation, and relative adsorptivities.
• Benzylamine showed higher adsorption and competed better with borate than propylamine.
• Borate effectively excluded lysine from the surface at pH ≥ 8, potentially due to silver oxide formation.

Conclusions:

• Borate interference is a significant issue in SER spectroscopy of basic analytes using silver colloids.
• Optimizing experimental conditions like pH and colloid surface can influence the extent of interference.
• Alternative SERS substrates may be necessary to eliminate borate adsorption and spectral interference for certain analytes.