A SO2-selective electrode based on a Zn-porphyrin for wine analysis

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Chemical Sensors

Background:

• Sulfur dioxide (SO2) is a critical analyte in various industrial and environmental applications, necessitating accurate detection methods.
• Development of selective and sensitive electrochemical sensors is crucial for real-time SO2 monitoring.

Purpose of the Study:

• To assess the performance of a novel SO2-selective electrode.
• To investigate the electrode's response mechanism and selectivity.
• To evaluate its applicability in complex matrices like wine.

Main Methods:

• Fabrication of a PVC membrane electrode incorporating 5,10,15,20-tetraphenyl(porphyrinate)zinc(II) as a neutral carrier.
• Conditioning the electrode in a diethylamine solution.
• Electrochemical characterization including potentiometric measurements over a wide concentration range.
• Selectivity evaluation against common interfering ions.
• Validation using wine samples and comparison with a reference method.

Main Results:

• The developed electrode demonstrated a selective anionic response to SO2 over four concentration decades.
• Achieved a Nernstian slope of -59.5 mV dec(-1) with a detection limit of 3.7×10(-6) mol L(-1).
• The response mechanism involves the displacement of a diethylamine:metalloporphyrin complex equilibrium within the membrane.
• High accuracy and precision were obtained in wine analysis compared to a reference method.

Conclusions:

• The zinc(II) porphyrinate-based electrode offers a promising tool for selective SO2 determination.
• The electrode's mechanism relies on ionophore complexation and displacement within the PVC membrane.
• The sensor is suitable for practical applications, including the analysis of SO2 in wine.