Factors affecting the reactivity and sensitivity of colorimetric probes for iron ion detection

초록

Iron colorimetric assays can be influenced by probe selectivity, ligand competition, pH, and redox conditions, leading to misinterpretation of iron chelation and redox activity. This study systematically evaluated the sensitivity and reactivity of three representative iron-binding probes, ferrozine, TPTZ, and thiocyanate, under different experimental conditions. Ferrozine reacted selectively and sensitively with Fe2(+), whereas TPTZ detected Fe2(+) and monitored Fe2(+) generated by Fe3(+) reduction. Thiocyanate responded preferentially to Fe3(+), but its signal was strongly affected by buffer composition and pH. Ferrozine showed higher Fe2(+) sensitivity than TPTZ, whereas TPTZ was less affected by EDTA interference in the ferric reducing antioxidant power-type assays. The combined use of ferrozine and thiocyanate distinguished Fe2(+) loss caused by chelation from that caused by oxidation through reciprocal absorbance changes at 562 and 470 nm. These findings support complementary probe selection for interpreting iron chelation and redox activity in controlled model systems.

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