Mediated, thin-layer cell, coulometric determination of redox-active iron on the surface of asbestos fibers.
Mediated, thin-layer cell, coulometric determination of redox-active iron on the surface of asbestos fibers.
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介导的薄层细胞库仑法测定石棉纤维表面的氧化还原活性铁。
DOI：
10.1021/ac00098a013
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发表时间：
1995
影响因子：
7.4
通讯作者：
Aust,AE
中科院分区：
文献类型：
--
作者：
Shen,Z;Parker,VD;Aust,AE
石棉纤维表面的氧化还原活性铁的检测和定量使用薄层细胞，库仑法与可溶性介质之间的矿物纤维和固体电极穿梭电子。工作电极和对电极由载玻片上的金膜组成，参比电极为银。将天冬氨酸纤维包埋在25 μ m厚的薄层细胞中。Hexaammineruthenium（II）或o-联茴香胺（双阳离子）分别用作还原或氧化介质。Hexaamineruthenium（III）发生单电子还原，质子化邻联茴香胺发生双电子氧化。测量涉及的总电荷的氧化或还原的表面固定的铁（II）或铁（III）的石棉纤维的测定。结果表明，青石棉和铁石棉的总氧化还原活性铁分别为4.3±0.7和3.3± 0.7nmol/mg。这对应于青石棉和铁石棉的可接近的氧化还原活性铁的表面覆盖率分别为约4.3 × 10-11 mol/cm 2和9.5 × 10 - 11 mol/cm 2。此外，Fe（II）构成的青石棉或铁石棉的表面上的可访问的氧化还原活性铁的76%或25%，分别。该方法也适用于表面有氧化还原活性物质的其他类型的固体材料。接触石棉会增加患支气管癌和间皮瘤的危险。1石棉致癌的机制尚不清楚。然而，最致癌的石棉，青石棉和铁石棉，含有27%的铁重量。2有人提出，与致癌纤维相关的铁可能催化氧的连续还原，导致高活性· OH的形成，这可以破坏DNA，导致癌症。3在生理上重要的还原剂如抗坏血酸存在下，Fe（III）也可以被还原为Fe（II），以连续的方式产生高水平的“OH”。铁可以通过螯合剂，如柠檬酸盐，以一定的速度从青石棉或铁石棉中动员出来。
Redox-active iron on the surface of asbestos fibers was detected and quantified using a thin-layer cell, coulometric method with soluble mediators to shuttle electrons between the mineral fibers and the solid electrode. The working andcounter electrodes consisted of goldfilms on a glass slide with reference electrodes of silver. Asbestos fibers were entrapped in a thin-layer cell of 25 fim thickness. Hexaammineruthenium (II) or o-dianisidine (dication) was used as the reducing or oxidizing mediator, respectively. Hexaammineruthenium (III) un-dergoes a one-electron reduction, and protonated o-dianisidine undergoes a sequential two-electron oxidation. The measurement involved determination of the total charge for the oxidation or reduction of surface-immobilized Fe (II) or Fe (III) on the asbestos fibers. Analy-sis of the results showed that crocidolite and amositehave 4.3±0.7 and 3.3±0.7 nmol/mg of totalredox-active iron that is accessible to the mediators, respectively. This corresponded to a surface coverage of accessible redoxactive iron of approximately 4.3 x 10-11 mol/cm2 for crocidolite and 9.5 x 1011 mol/cm2 for amosite. Furthermore, Fe (II) constituted 76% or 25% of the accessible redox-active iron on the surface of crocidolite or amosite, respectively. Hie method may be applied to other types of solid materials with redox-active species on their surfaces.Exposure to asbestos results in an increased risk of bronchogenic carcinoma and mesothelioma. 1 The mechanism by which asbestos causes cancer is not well understood. However, the most carcinogenic forms of asbestos, crocidolite and amosite, contain 27% iron by weight. 2 It has been proposed that iron associated with the carcinogenic fibersmay catalyze sequential reduction of oxygen, leading to the formation of the highly reactive• OH, which can damage DNA resulting in cancer. 3 In the presence of a physiologically important reductant, such as ascor-bate, Fe (III) may also be reduced to Fe (II), producing a high level of’OH in a continuous manner. Iron can be mobilized from crocidolite or amosite asbestos by chelators, such as citrate, in a