Modified Diacetylmonoxime-Thiosemicarbazide Detection Protocol for Accurate Quantification of Urea

Renewable photo-/electrocatalytic coreduction of CO₂ and nitrate to urea is a promising method for high-value utilization of CO₂ . However, because of the low yields of the urea synthesis by photo-/electrocatalysis process, the accurate quantification of low concentration urea is challenging. The traditional diacetylmonoxime-thiosemicarbazide (DAMO-TSC) method for urea detection has a high limit of quantification and accuracy, but it is easily affected by NO₂ ^- in the solution, which limits its application scope. Thus, the DAMO-TSC method urgently requires a more rigorous design to eliminate the effects of NO₂ ^- and accurately quantify urea in nitrate systems. Herein, a modified DAMO-TSC method is reported, which consumes NO₂ ^- in solution through a nitrogen release reaction; hence, the remaining products do not affect the accuracy of urea detection. The results of detecting urea solutions with different NO₂ ^- concentrations (within 30 ppm) show that the improved method can effectively control the error of urea detection within 3%.