A chalcone-based Schiff base (5), capable of detecting iron (III) in partially aqueous media, has been designed, then synthesized by the condensation of 3-formyl-2-hydroxyquinoline and acetophenone. To determine iron (III) ion, a simple spectrofluorimetric method was developed by using the synthesized Schiff base. The developed method was validated by analyzing the certified reference material (CRM-SA-C Sandy Soil C). During the process of the determination of iron in food samples, satisfactory accuracy was obtained for spinach and rocket. Nitric acid and hydrogen fluoride were used for the digestion of the certified reference material whereas only nitric acid was used for food samples, in a closed microwave system. Measurements were carried out by using the modified standard addition method. The standard addition graph was linear until 5.0 mg/L. in determination of iron (III). Detection and quantification limits were 0.06 and 0.20 mg/L., respectively. The presented method is simple, time-saving, cost-effective and suitable for determination of iron content of soil and foods.