Graduate School of Biotechnology and Environmental Monitoring, Federal University of São Carlos (UFSCar), Rodovia João Leme dos Santos, SP-264, km 110, Sorocaba, São Paulo, 18052-780, Brazil.
Department of Physics, Chemistry and Mathematics, Federal University of São Carlos (UFSCar), Rodovia João Leme dos Santos, SP-264, km 110, Sorocaba, São Paulo, 18052-780, Brazil.
Environ Monit Assess. 2021 Jan 15;193(2):63. doi: 10.1007/s10661-021-08874-w.
Iron is an essential mineral and one of the most abundant in soils, presenting itself in the environment as ferrous and ferric ions. As each oxidation state of iron has a different role in the environment, its speciation in environmental studies is important. The determination of ferrous iron received great attention from soil chemists because of its important role in agriculture, in redox processes, and as an electron acceptor in the catalysis of organic matter. Methodologies with the use of colorimetric reagents to determine ferrous iron are divergent and not very clear. In this study, we compared two colorimetric reagents (1,10-phenanthroline and ferrozine) to determine the total concentration of iron, ferrous and ferric ions in soil, using simple and low-cost methodologies. The determination of ferrous and total iron with 1,10-phenanthroline colorimetric reagent, following published instructions, did not correlate with ferrozine method, presenting an erroneous quantification. After neutralizing the extract of 1,10-phenanthroline with NaOH, both colorimetric methods allowed to quantify with precision and high yield the amount of ferrous and total iron extracted from the soil. The oxidation states of iron have a different contribution and importance to the environment. In this sense, the improvement of a widely used methodology is crucial for the better study of iron speciation in soil.
铁是一种必需的矿物质，也是土壤中最丰富的矿物质之一，以亚铁离子和铁离子的形式存在于环境中。由于铁的每种氧化态在环境中都有不同的作用，因此其在环境研究中的形态分析非常重要。由于亚铁在农业、氧化还原过程以及有机物催化中的电子接受体中起着重要作用，因此土壤化学家对其的测定给予了极大的关注。使用比色试剂测定亚铁的方法多种多样，且并不十分明确。在这项研究中，我们使用简单且低成本的方法，比较了两种比色试剂（邻菲啰啉和菲啰啉）来测定土壤中铁、亚铁和铁离子的总浓度。根据已发表的说明，使用邻菲啰啉比色试剂测定亚铁和总铁与菲啰啉法不相关，存在错误的定量结果。用 NaOH 中和邻菲啰啉提取物后，两种比色法都可以精确、高效地定量从土壤中提取的亚铁和总铁的含量。铁的氧化态对环境有不同的贡献和重要性。在这方面，改进一种广泛使用的方法对于更好地研究土壤中铁的形态至关重要。
