Electrochemical urea synthesis represents a promising pathway toward sustainable nitrogen management and carbon utilization, offering a potential alternative to the energy- and carbon-intensive Haber-Bosch process and conventional urea production from fossil-derived feedstocks. By directly coupling CO₂ and nitrate conversion under mild conditions, this process exemplifies a circular approach to nitrogen fixation. However, the realization of efficient and selective electrochemical urea synthesis is critically hindered by the lack of reliable analytical methods capable of detecting and quantifying urea at sub-micromolar concentrations. This analytical limitation not only impedes accurate benchmarking of catalytic performance but also constrains the predictive design of catalysts and electrochemical systems for sustainable production.

In this work, we systematically assess and optimize existing urea quantification techniques – including high-performance liquid chromatography (HPLC), proton nuclear magnetic resonance (¹H NMR), and colorimetric assays such as urease-based and DAMO–TSC methods – highlighting their inherent limitations in sensitivity, selectivity, and robustness. HPLC and ¹H NMR, while analytically robust, exhibit high limits of quantification (LOQ > 50 μM), making them unsuitable for trace-level detection. Colorimetric methods offer lower LOQs (typically >3 μM), but are highly sensitive to matrix effects and interference from by-products such as nitrite. We address this challenge by introducing sulfamic acid as an effective nitrite scavenger in the DAMO-TSC protocol, significantly improving its reliability in complex reaction matrices. Furthermore, we enhance the urease-based method by replacing conventional UV-vis quantification of ammonia with ion chromatography (IC), which offers improved precision and interference tolerance.

Building upon these insights, we develop a novel analytical framework based on ion chromatography coupled with mass spectrometry (IC–MS), achieving a quantification limit below 5 ppb. This technique provides unparalleled sensitivity and selectivity for urea detection, enabling the rigorous evaluation of catalytic systems that operate at trace production levels. By establishing a robust and interference-free methodology, this work provides a critical analytical foundation for the field of electrochemical urea synthesis. The approach not only facilitates meaningful benchmarking of catalyst activity and selectivity but also enables feedback-driven optimization through quantitative structure-activity relationships and reaction environment design.

These analytical advancements directly support the goals of sustainable catalysis and circular carbon-nitrogen chemistry by bridging analytical precision with materials innovation. We will also offer insights into the implementation of these detection strategies informs the rational design of catalysts and electrolyzer systems, ultimately advancing the development of energy-efficient, selective, and scalable routes for sustainable urea production.