铬的化学形态分析进展

有关痕量元素形态的研究已成为当今科学领域的活跃领域之一,是分析工作者必须面对的新课题.同一元素不同的化学形态导致不同的环境毒害、生物效应和对人体健康有不同的影响.铬是VIB族元素,在地壳中的平均含量为 0.010%～0.011%,分布广泛.工业上主要用于制造各种优质合金,也广泛用于皮革、印染、电镀等工业,受腐蚀后以各种排放液进入环境.铬有多种价态,最常见的是三价和六价.研究表明,铬表现为必需元素还是有害元素,其价态起决定性作用.三价铬是人体必需的微量元素,是正常糖脂代谢所不可缺少的,缺铬会引起动脉硬化等多种疾病.六价铬由于其氧化性和对皮肤的高渗透性,毒害很大,被确认有致癌作用.铬形态分布也影响铬在环境中的迁移转化规律.因此铬的形态分析在环境科学、生命科学、生理医学等方面都有重要的意义.     

茶汤及河水中铬的形态分析

本文采用７１７型强碱性阴离子交换树脂、活性炭分离富集与偶氮胂Ⅲ光度法结合，研究了铬形态的分离及测定，提出了铬的形态分析方法，有此法测定了茶汤及河水中铬的总量，悬浮态．溶解态、无机态、有机态、Ｃｒ（Ⅲ）和Ｃｒ（Ⅵ）。茶汤中铬主要以有机态存在，而河水中铬则主要以悬浮态存在。     

环境中无机铬形态分析研究进展

本文对近年来环境分析化学中的一个重要分支－环境中无机铬的形态分析进展及有关分析方法的现况和发展趋势进行了概述。     

环境中铬形态分析研究进展

对近10年来国内外在环境中铬形态方面的分析研究进展作了综述,内容包括样品预处理、分离富集方法和样品检测方法(引述文献61篇).     

电化学分析法在铬形态分析中应用进展

对近年来电化学分析法应用于铬的形态分析的现状和发展趋势进行了概述。     

塞曼原子吸收分光光度法测定人发样中痕量镍,铬,锰

提供了测定人发中微量金属元素Ｎｉ、Ｃｒ、Ｍｎ的塞慢原子吸收分析法，采用国产石墨管、空心阴极灯对分析条件进行了考察选择，并对人发标准参考物质进行测定。     

巯基棉吸附分离法测定水中铬,镍

探讨了巯基棉在不同吸附条件下对水中Ｃｒ＾６＋、Ｎｉ＾２＋的定量吸附，并用原子吸收分光光度法分别测定其含量。巯基棉吸附效率高，定量解脱完全，待测元素的分离富集选择性强。此法灵敏度高，误差小。     

糖尿病患者血清中铬钴镍钙镁含量的探讨

测定了１１１例糖尿病患者血清中铬、钴、镍、钙、镁的含量，与对照组比较，铬、钴、钙、镁均出现降低，两者差异有高度显著性，Ｐ〈０．０１。提示可根据以上元素含量变化辅助诊断和防治糖尿病。     

铬的形态分析研究与进展

综述了Cr(Ⅲ)、Cr(Ⅵ)形态分析的发展。内容包括概述、样品分离富集、光谱分析、色谱分析等。引用文献43篇。     

用卡尔曼滤波-分光光度法测定无机铬的形态

利用Ｋａｌｍａｎ滤波技术和二溴苯基荧光酮－溴化十六烷基三甲基铵－Ｃ_２Ｈ_５ＯＨ分光光度测定体系,同时对Ｃｒ（Ⅲ）和Ｃｒ（Ⅳ）进行测定。Ｃｒ（Ⅲ）的表观摩尔吸光系数为１．９６ × １０~５ Ｌ· ｍｏｌ~（－１）·ｃｍ~（－１）,线性范围为０～ ４．０ ｘ１０－６ｍｏｌ／Ｌ;Ｃｒ（Ⅵ）的表观摩尔吸光系数为４．１６ ×１０~５Ｌ· ｍｏｌ~（－１）· ｃｍ~（－１）,线性范围为０～５．２×１０~（－１）ｍｏｌ／Ｌ。     

土壤中锰的形态分析方法研究

采用Tessler的连续浸取程序，利用La-Zr涂履石墨管，石墨炉原子吸收光谱对土壤中不同形态锰的浸取与测定的条件进行了研究。经过对土样－3各形态的浸取液进行加标试验，其回收率在90%－110%，测定了一组土样，结果满意。     

Speciation Analysis of Chromium by Adsorptive Stripping Voltammetry in Tap and River Water Samples

An adsorptive stripping voltammetric method for speciation analysis of chromium in natural water samples has been developed. Ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) were used as complexing agents for Cr(III) present in the sample and formed as products of Cr(VI) reduction, respectively. Under optimum experimental conditions linear relations in the range from 1×10^?6 to 3×10^?5 mol L^?1 without accumulation and from 1×10^?9 to 1×10^?7 at 30 s accumulation time were obtained for Cr(III) and Cr(VI), respectively. For samples in which Cr(III) concentration is higher than 1×10^?6 mol L^?1 the Cr(III) and Cr(VI) were determined simultaneously in one voltammetric cell. For samples in which Cr(III) concentration is below 1×10^?6 mol L^?1 only Cr(VI) was selectively determined in the presence of Cr(III), which did not influence the Cr(VI) signal. The determination of Cr(III) and Cr(VI) was successful with the application of the proposed procedure in the presence of common foreign ions. The presented method was applied for the speciation of chromium in spiked tap and river water samples with satisfactory results.     

纳米二氧化锆微柱分离电感耦合等离子-质谱分析水样中铬的形态

以纳米ZrO2为微柱填充材料,采用电感耦合等离子-质谱(ICP-MS)研究了Cr(Ⅵ)/Cr(Ⅲ)在纳米ZrO2微柱上的吸附性能。当pH值为8时,纳米ZrO2能完全吸附Cr(Ⅲ),而对Cr(Ⅵ)基本不吸附。对影响Cr(Ⅵ)和Cr(Ⅲ)分离的主要因素进行了详细研究,据此建立了纳米ZrO2微柱分离ICP-MS分析铬形态的新方法。方法对铬的检出限(3σ)为0.06ng/mL,定量测定下限(10σ)为0.37ng/mL,相对标准偏差为2.2%(n=9,c=100ng/mL)。本法选择性好、简便、快速,已用于不同水样中铬形态的测定,结果满意。     

模拟退火-BP神经网络法测定无机铬的形态

提出了用神经网络方法测定无机铬的形态。在Back Propagation(BP)算法的基础上,吸取了模拟退火算法的优点,解决了BP算法容易陷入局部极小点的问题。经实际样品分析,结果满意。     

纳米二氧化钛分离富集和ICP-AES测定水样中Cr(Ⅵ)/Cr(Ⅲ)

利用ＩＣＰ－ＡＥＳ研究了纳米ＴｉＯ２材料对Ｃｒ（Ⅵ）／Ｃｒ（Ⅲ）的吸附性能,并将其用于水样中铬的形态分析。结果表明,该法对１０ｍＬ试样测定Ｃｒ（Ⅵ）和Ｃｒ（Ⅲ）的检测限分别为６１ｎｇ／ｍＬ和４５ｎｇ／ｍＬ,其浓度在０．１～１０ｕｇ／ｍＬ范围内线性关系良好,５０倍量的Ｃｒ（Ⅵ）对Ｃｒ（Ⅲ）的检测不产生干扰。本法测定Ｃｒ（Ⅵ）和Ｃｒ（Ⅲ）的相对标准偏差分别为３．６％和４．２％（ｃ＝２．０ｕｇ／ｍＬ,ｎ     

湘江(长沙段)水中铬的形态分布及其迁移

研究了湘江水中铬的存在形态、分离方法和分析流程。用极谱催化法测定了江水中的总铬、总溶解铬、颗粒态铬、有机态铬、溶解无机铬、溶解无机态Cr(Ⅵ)、溶解无机态Cr(Ⅲ)。分析了不同季节里铬的存在形态及其迁移转化。结果表明溶解无机态铬是主要的存在形态,其中溶解无机态Cr(Ⅵ)较易转化成毒性较小的Cr(Ⅲ)。不同季节中铬的各形态的含量不同,其中颗粒态铬和有机态铬在夏季的含量较高,而其余各形态的铬在秋、冬两季的含量高于春、夏两季。江水对铬污染的自净能力较强,铬造成的污染的范围较小。     

Speciation of hexavalent chromium in waters by liquid-liquid extraction and GFAAS determination

Diperoxo chromium oxide is produced by reaction of hydrogen peroxide on chromium(VI). Diperoxo chromium creates a complex with ethyl acetate, while chromium(III) remains in an unchanged form in the aqueous phase. By this means chromium(VI) can be extracted into ethyl acetate from the aqueous phase. The optimal conditions of Cr(III)-Cr(VI) separation, as well as the chromium content of the ethyl acetate phase were determined with graphite furnace atomic absorption spectrometry. In the second extraction of Cr(VI) from ethyl acetate back into water phase an additional preconcentration of chromium(VI) can be carried out. The detection limit (3σ) of the developed method found to be 200 ng dm^− 3 for the first extraction and 50 ng dm^− 3 after using the twofold extraction. In consequence of the matrix free ethyl acetate phase after the first extraction, with this separation a really extensive preconcentration of chromium(VI) can be realized.     

Speciation of Chromium in Natural Waters,Tea, and Soil with Membrane Filtration Flame Atomic Absorption Spectrometry

A sensitive and selective method was developed for the speciation of chromium(III) and chromium(VI) in environmental samples based on membrane filtration and determination by flame atomic absorption spectrometry. Chromium(III) reacts with cochineal red A, yielding a complex that is adsorbed on a cellulose acetate membrane filter, whereas chromium(VI) remains in aqueous solution, permitting separation. After reduction of chromium(VI) to chromium(III) with hydroxylamine hydrochloride, the total concentration of chromium was determined, and the concentration of chromium(VI) was calculated by subtraction. The pH, amount of cochineal red A, and sample volume were optimized on the basis of the recovery of Cr(III). The influence of matrix ions was also investigated. The preconcentration factor was 94. The detection limit (3 sigma) for Cr(III) was 1.4 micrograms per liter. The method was validated using environmental certified reference materials. The method was successfully employed for the speciation of chromium in wastewater and lake water.