鉴别Fe~(2+)离子与Fe~(3+)离子方法14种

鉴别Fe~(2+)离子和Fe~(3+)离子的方法很多,下面列出14种。 1.可溶性硫氰化物法用2支试管分取两种溶液各少量,分别滴入可溶性硫氰化物(如KSCN、NaSCN、NH_4SCN)等溶液,变血红色的是Fe~(3+)的溶液:Fe~(3+)+SCN~-=Fe(SCN)~(2+)     

对“鉴别 Fe~(2+)离子和 Fe~(3+)离子方法14种”一文的商讨

贵刊1987年第3期刊登的“鉴别 Fe~(2+)离子和 Fe~(3+)离子方法14种”一文,有几处不妥的地方,提出一点看法,以便商讨。一、二氧化硫法将 SO_2分别通入含 Fe~(2+)和 Fe~(3+)的溶液中,该文所叙述的现象和反应方程式,是错误的。1.从实验的角度讲,将 SO_2通入含 Fe~(2+)的溶液中并无浅黄色浑浊出现。为此,我又作了专门的验证实验,发现溶液中既无硫沉淀,也无 FeSO_(?)沉淀,(因溶液绝对呈酸性。)溶液也未呈褐黄色。2.从理论上讲,依电极电位(酸性介质):H_2SO_3+4H~++4e(?)S↓+3H_2OE~0=0.45伏Fe~(3+)+e(?)Fe~(2+) E~0=0.770伏显然,E~0H_2SO_3/S E~0Fe~(3+)/Fe~(2(?)),说明在酸性条件下,只能是 Fe~(3+)将 S 氧化为 H_2SO_3,而不     

用沉淀滴定法测定磷矿中的磷

在酸性试液中加入捕捉剂,以二甲酚橙(XO)为指示剂,经实验证明可用标准硝酸铋直接滴定试液中的PO_4~(3-)离子。滴定在较强的酸性溶液中进行,可消除能与PO_4~(-3)生成难溶盐的阳离子的干扰。XO在该滴定条件下不封闭Al~(3+)(200mgAl_2O_3)。Fe~(3+)(50mg)用抗坏血酸还原为Fe~(2+)可消除干扰。As~(3+)离子严重干扰测定,当用王水溶样,将As~(3+)氧化为AsO_4~(3-)的形式,则可使砷     

罗丹明类Schiff碱荧光探针对Fe~(3+)的特异性识别研究

基于罗丹明结构设计合成了一种新型Schiff碱类荧光探针。随着Fe~(3+)的加入,探针溶液表现出明显的荧光增强,该现象表明探针和Fe~(3+)络合能力较强,避免了因Fe~(3+)自身磁性引起的荧光猝灭。探针在识别Fe~(3+)时,表现出很好的选择性,并且识别过程不受其他常见干扰离子的影响。进一步,通过job’s曲线和高斯理论计算对探针的识别机理进行了较深入的探究,得到探针与Fe~(3+)按照1∶1络合的结论,并提出了可能的络合位点和识别过程。     

Fe~(3+)-Sn~(2+)-F~-还原体系中的两种磷钼兰

钼兰法应用于磷的测定,已有近九十年历史。对磷钼兰某些性质,国内外虽有研究,但意见分岐较大。尤其对磷钼兰中钼的价态报导比较混乱,国内尚未见专文沦述。我们在应用氟化钠-氯化亚锡钼兰法测磷时发现,随着试液中Fe~(8+)及Sn~(2+)量的变化,能产生两种不同性质的磷钼兰,进而确定系钼的价态不同。过去一些资料,对此未加阐述,致试液中Fe~(8+)量变化后     

Fe~(3+)掺杂的TiO_2纳米复合粒子的合成及表征

利用酸催化的溶胶-凝胶法合成了一系列不同Fe~(3+)掺杂量的TiO_2纳米复合 料子。用XRD,TEM,UV-vis等技术进行了表征。结果表明：在所研究的掺杂量范围 内(x_B = 0.0005 ～0.1000),未发现有铁氧化物的晶相生成;Fe~(3+)的掺杂可以 实现TiO_2由锐钛矿(anatase)结构向金红石(rutile)结构的低温转化,随着Fe~ (3+)掺杂量的增大,对光的吸收发生红移,吸收强度增大。掺杂适量的Fe~(3+)可 以使TiO_2纳米微粒的光催化活性得以提高。     

新型Fe~(3+)荧光探针及其生物成像研究（英文）

以罗丹明为基础合成、表征了一种"turn-on"型荧光探针.该探针对Fe~(3+)表现出很高的选择性和灵敏性.将Fe~(3+)加入到探针中,溶液的紫外吸收值和荧光强度都有很明显的变化,同时伴随着肉眼可见的溶液颜色改变.研究发现,探针与Fe~(3+)按照1∶1进行络合,引起了探针内酰胺环的打开,进而吸收值和荧光强度值发生变化.研究表明,在有其他共存离子存在下,该探针仍然可以有效检测Fe~(3+).细胞实验发现,探针可以穿过细胞膜,在细胞内与Fe~(3+)作用,同时也可检测小鼠体内Fe~(3+),呈现出很好的荧光成像效果.     

Fe~(2+)在不同酸度中的稳定性

读了本刊1984年第三期Fe(OH)_2制备试验中的几个问题一文后。笔者认为要探讨问题,最好采用定量实验的方法,粗略实验往往会影响结论的准确性。本文以定量分析法对Fe~(2+)在不同酸度中的稳定性进行了定量测定。结果证实:Fe~(2+)被空气中氧气氧化的速度是随着溶液酸度增加而降低,甚至被抑制。并不是“溶液酸度愈高,Fg~(2+)被氧化的速度愈大。”兹将实验结果,介绍如下供商榷。     

Fe~(3+)辅助煤浆氧化制氢研究

利用Fe~(3+)/Fe~(2+)电对的相互转化原理,在水热反应釜中用Fe~(3+)氧化煤浆得到Fe~(2+),将Fe~(2+)在电解槽中电解氧化,在阴极产生氢气,从而通过两步反应形成一个新的煤浆电氧化制氢工艺。进行了九次水热-电解循环实验,在恒电压(1V)条件下,测试了电解反应的电流密度和累积电量的数据,并对循环实验前期、中期、后期的三个阶段煤样品进行了扫描电镜(SEM)、比表面积(BET)、热重(TG)、红外光谱(FT-IR)等表征分析。研究表明,相对于通常煤浆电氧化制氢工艺,这种"两步法"煤浆制氢新工艺具有更高的反应速率,初始电流密度约为60 m A/cm2,而传统的"一步法"煤浆制氢工艺初始电流密度均不超过10 m A/cm~2。表征分析结果很好地反映了煤颗粒在这种制氢工艺过程中的形态、结构、成分的变化,从而解释了在新的煤浆氧化制氢工艺中的Fe~(3+)/Fe~(2+)转化的反应机理。     

基于功能化萘二甲酰亚胺席夫碱的Fe~(3+)传感器分子的合成及性能

将功能化的1,8-萘二甲酰亚胺衍生物与羟基萘甲醛缩合,合成了一种新颖的传感器分子2-羟基-1-奈甲醛缩N-(4-氨基苯基)-1,8-奈二甲酰胺席夫碱(H1).通过核磁共振氢谱,碳谱和高分辨质谱等方法对H1进行了表征.测定了H1在二甲基亚砜(DMSO)/H_2O(V:V=7:3)溶液中的荧光光谱,其最大荧光发射波长为496nm.H1的溶液在365 nm紫外灯照射下显示黄绿色荧光.H1对Fe~(3+)具有荧光-比色双通道检测能力.当在H1的DMSO/H_2O溶液中分别加入Fe~(3+),Ag~+,Ca~(2+),Ba~(2+),CO~(2+),Ni~(2+),Cd~(2+),Pb~(2+),Zn~(2+),Cu~(2+),Mg~(2+)和Hg~(2+)等阳离子时,只有Fe~(3+)的加入使H1的荧光猝灭并且溶液颜色褪色.抗干扰实验结果表明,这一识别过程不受其它阳离子干扰.H1对Fe~(3+)具有较高的检测灵敏度,对Fe~(3+)的荧光光谱最低检测限和紫外-可见吸收光谱最低检测限分别为3.04×10~(-8)和2.71×10~(-6+mol·L~(-1).最后,制备了基于H1的检测试纸,该试纸可以方便快捷地检测水中的Fe~(3+).     

The role of Fe3+ on Fe2+-dependent lipid peroxidation in phospholipid liposomes

Fe2+-dependent lipid peroxidation in phosphatidylcholine (PC) liposomes, assessed by thiobarbituric acid-reactive substances (TBARS) production, was stimulated in the presence of Fe3+ in a concentration-dependent manner. The rates of nitroblue tetrazolium (NBT) reduction and Fe2+ oxidation (Fe2+ disappearance and Fe3+ formation) were also enhanced by the addition of Fe3+ to the reaction mixture, and there is a good linear relationship between these parameters. These results suggest that the facilitation of reactive oxygen species (ROS) production via Fe2+ oxidation is closely related to the onset of the stimulatory effect of Fe3+ on Fe2+-dependent lipid peroxidation. On the other hand, results using the liposomes containing various concentrations of endogenous lipid hydroperoxides (LOOH) indicated that endogenous LOOH is not directly involved in the onset of the Fe3+ stimulatory effect on Fe2+-dependent TBARS production and ROS production. This hypothesis was further confirmed by the evidence that Fe2+-dependent ROS production and Fe2+ oxidation of dipalmitoylphosphatidylcholine liposomes were also stimulated by the addition of Fe3+. The results with several antioxidants and radical scavengers suggested that ROS related to Fe2+-dependent lipid peroxidation and its stimulation by Fe3+ are ferrous-oxygen complexes rather than superoxide anion, hydrogen peroxide and hydroxyl radicals. Based on these results, we proposed a possible mechanism for the onset of the Fe3+ stimulation in Fe2+-dependent lipid peroxidation.     

Anion influence on the hydrated oxides formed by Fe3+ and Fe2+ precipitation

The anion influence on the hydrated oxides formed by Fe³⁺ and Fe²⁺ precipitation simulating the aqueous radioactive waste treatment has been investigated by Mössbauer spectroscopy. Fe₃(SO₄)₂, Fe(NO₃)₃, FeCl₃, FeSO₄ and FeCl₂ were used as iron sources and neutralized by NaOH. The obtained products contain several kinds of amorphous and/or poorly crystallized hydrated oxides, depending on the anion type which exists in solution and on the initial iron valence. The pH influence on the final precipitate is taken into account.     

Zum System H2O2, Fe2+-, Fe3+-Ion

Ohne Zusammenfassung     

Fe+ chemical ionization of peptides

Laser-desorbed peptide neutral molecules were allowed to react with Fe⁺ in a Fourier transform mass spectrometer, using the technique of laser desorption/chemical ionization. The Fe⁺ ions are formed by laser ablation of a steel target, as well as by dissociative charge-exchange ionization of ferrocene with Ne⁺. Prior to reaction with laser-desorbed peptide molecules, Fe⁺ ions undergo 20–100 thermalizin collisions with xenon to reduce the population of excited-state metal ion species. The Fe⁺ ions that have not experienced thermalizing collisions undergo charge exchange with peptide molecules. Iron ions that undergo thermalizing collisions before they are allowed to react with peptides are found to undergo charge exchange and to form adduct species [M + Fe⁺] and fragment ions that result from the loss of small, stable molecules, such as H₂O, CO, and CO₂, from the metal ion-peptide complex.     

Simulating Nuclear subsystem rearrangement in the redox reaction between Fe2+ and Fe3+ ions

An approach that allows the numerical simulation of conformational rearrangements accompanying redox reactions in molecular systems is examined. The proposed method makes it possible on the basis of metadynamics to identify automatically the groups of atoms whose conformational motions give rise to changes in the redox properties of an investigated system. The method is used to simulate a classic model electron transfer reaction, i.e., the redox reaction between Fe²⁺ and Fe³⁺ ions in a solution. The effective activation energy of the reaction is reproduced quantitatively, and the reaction coordinate is determined. It is shown that this approach is promising for use in studying conformational changes that are associated with electron transport processes in complex molecular systems.     

Simultaneous Determinations of Fe2+ and Fe3+ in Ferrous Sulfate Destined for Pharmaceutical Preparations

ABSTRACT

Only the simultaneous analysis of the amount of Fe^2? and the possible presence of Fe³⁺ in ferrous sulfate heptahydrated (FeSO_4. 7 H₂O) can guarantee covered tablets, drops or syrups with insured quality. This work suggests that these analysis are accomplished through spectrophotometric method by use of the 1, 10-phenanthroline as chelate. Thus, at 510 nm the absorption is only due to the complex of the ligand with Fe^2? and at 390 nm the absorption is indicative of Fe^2+/3+ coordinated. Pharmaceutical raw matter and covered tablets were analyzed. Techniques of thermogravimetric analysis (TG-DTG) were used for the knowledge of the regions of loss of water of the FeSO₄. 7 H₂O for the relationship to its stoichiometry.     

Local tilting angles tau for Fe+ in Cd2+ site and Fe3+ in Si4+ site of CdSiP2 semiconductor

The EPR parameters (g factors, g(parallel), g(perdendicular) and zero-field splitting D) for Fe+ in Cd2+ site and Fe3+ in Si4+ site of CdSiP2 semiconductor are calculated from the distinct high-order perturbation formulas. From the calculations, the local tetragonal distortions and hence the local tilting angles tau (which are different from the corresponding host values) for both paramagnetic centers are estimated. The results are discussed.     

酸性溶液中Fe2+ /Fe3+相互转换对电极还原行为的影响

采用线性扫描伏安法和循环伏安法研究了含有Cl^-、SO₄^2-的酸性溶液中Fe²⁺/Fe³⁺相互转换对电极反应和Fe³⁺还原过程的影响. 结果表明: [Fe]_T=1 mol·L-1条件下,溶液中Fe³⁺/Fe²⁺的还原析出过程经过两个阶段：(1) E=0.35 V左右Fe³⁺还原成Fe²⁺过程; (2) E=-0.3 V之后H+的还原同时Fe²⁺离子与OH^-相结合生产Fe(OH)₂; Fe³⁺/Fe²⁺的相互转化主要影响Fe³⁺的第一还原阶段的还原峰电流和峰电位. |ipa/ipc|值随c(Fe³⁺ )/c(Fe²⁺ )增大而增大,且扫描速度慢时影响大,扫描速度快时影响小; 0.50 mol·L^-1 Fe²⁺+0.50 mol·L^-1 Fe³⁺时,随扫描速率的变化|ipa/ipc|值变化最小(|i_pa/i_pc|≈1.20). 同时,c(Fe³⁺ )/c(Fe²⁺ )也影响平衡电位,平衡电位随c(Fe³⁺ )/c(Fe²⁺ )增大而正移,电位从E₁=0.501 V升至E₅=0.565 V.