Amperometric sensor for nanomolar nitrous oxide analysis.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Oceanography

Background:

• Nitrous oxide (N₂O) is a significant greenhouse gas with atmospheric equilibrium concentrations around 9.6 nM in water.
• Sensitive detection methods are crucial for studying N₂O distribution in various environmental compartments.
• Existing techniques may lack the required sensitivity for low-concentration N₂O measurements.

Purpose of the Study:

• To develop and present a novel electrochemical sensor for quantifying N₂O at nanomolar levels.
• To achieve high sensitivity and minimize interference for accurate N₂O detection.
• To validate the sensor's performance in a real-world oceanic setting.

Main Methods:

• An electrochemical sensor utilizing a front guard cathode to modulate N₂O flux to a measuring cathode.
• Employing an oxygen-consuming electrolyte to prevent oxygen interference.
• Field deployment to measure an N₂O depth profile in the Eastern Tropical North Pacific Ocean (ETNP).

Main Results:

• The sensor achieves a sensitivity of 2 nM N₂O for newly constructed devices.
• The signal amplitude method effectively mitigates baseline current drift.
• Successful measurement of an N₂O profile down to 120 meters in the ETNP's oxygen minimum zone.

Conclusions:

• The developed electrochemical sensor provides a highly sensitive method for N₂O quantification in the nanomolar range.
• The sensor design effectively overcomes common challenges like baseline drift and oxygen interference.
• The field test demonstrates the sensor's capability for environmental monitoring in complex marine environments.