p-Dimethylaminobenzalrhodanine is primarily used as a reagent in analytical chemistry for the detection and determination of various metal ions. It is particularly effective in identifying silver, mercury, and copper ions due to its ability to form colored complexes with these metals. This property makes it valuable in qualitative and quantitative analysis, especially in environmental testing and industrial quality control processes. Additionally, it has applications in research laboratories for studying metal-ligand interactions and developing new analytical methods. Its sensitivity and selectivity make it a useful tool in trace metal analysis.