Flow injection 4 article 4 diphenylcarbazide 4 1,5-diphenylcarbazide (DPC) 2 Catalyst activity 2 Catalysts 2 Catalytic oxidation 2 Chemical reactions 2 Chromium(vi) determination 2 Copper 2 Cu 2 DPC 2 Diphenylcarbazone (DPCO) 2 Kinetic methods 2 Magnesium printing plates 2 On-line dissolution 2 Optimization 2 Oxidation 2 Reaction kinetics 2 Sensitivity analysis 2 Spectrophotometric determination 2 Water 2 calculation 2 catalysis 2 catalyst 2 chemical parameters 2 chemical reaction 2 chromium 2 copper 2 dispersion 2