Versatile applicability of a new reagent for iron(II) determination in pharmaceutical products, foodstuffs, soil, and water samples

The present study aimed to develop a simple, sensitive, and versatile spectrophotometric method for the determination of Fe(II) in pharmaceutical formulations, foodstuffs, water, and soil samples. The synthesis and analytical performance of the proposed method were evaluated. A new organic compound, 4-(2,3,4-trihydroxyphenylazo)antipyrine (4-THPA), was employed as the chromogenic reagent. Among more than 20 investigated metal ions, 4-THPA selectively reacted with iron(II) to form a violet-colored complex. Under optimized experimental conditions, the method exhibited linearity over the concentration range of 0.15-25 μg·mL-1 for Fe(II). The molar absorptivity was calculated to be 9.9 × 10³ L·mol-1·cm-1, and Sandell’s sensitivity was 0.0015 μg·cm-2. The limits of detection and quantification for Fe(II) were 0.021 μg·mL-1 and 0.069 μg·mL-1, respectively. The accuracy, validity, and efficiency of the proposed method were evaluated by analyzing various samples, and the results were compared with those obtained using flame atomic absorption spectroscopy. A good agreement between the two methods was observed, confirming that the proposed spectrophotometric method is a reliable and efficient approach for iron determination in diverse sample matrices.