Fig. 1A

Absorption spectrum of norfloxacin (a), Absorption spectrum of color complex (b). Condition: 1.0 mL of Fe³⁺ (0.002 mol/L), 30 µg/mL of norfloxacin, 1.0 mL of 1,10-phenanthroline (0.006 M), heated at 100 ° C for 15 min, diluted to 10 mL