Fig. 2From: Novel allyl-hydrazones including 2,4-dinitrophenyl and 1,2,3-triazole moieties as optical sensor for ammonia and chromium ions in watera The plot of changes in UV–visible spectra of compound 4a solution as a function of different ammonia concentrations (0–20 ppm), b the linear relationship between different ammonia concentrations and absorbance intensity at 549 nm wavelengthBack to article page