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).     

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。     

流动注射在线富集分离-火焰原子吸收光谱法测定水体中的铬(Ⅲ)和铬(Ⅵ)

内装活性氧化铝（碱式）和阴离子交换树脂的微型柱流动注射在线富集分离水体中的铬（Ⅲ）和铬（Ⅵ），火焰原子吸收法直接检测。微型住可同时富集两种价态的离子，分别用1mol／L的NH4NO3和HNO3洗脱Cr（Ⅵ）和Cr（Ⅲ）于喷雾器中。进样时间25s，铬（Ⅵ）和铬（Ⅲ）的富集倍数分别为11倍和20倍，实际水样的加标回收率在90％～106％之间；分析速率为50个样／h；铬（Ⅵ）、铬（Ⅲ）的检出限（3δ）分别为1．5μg／L和0．7μg／L；相对标准偏差（50μg／L）分别为1．9％和2．6％。     

流动注射在线富集分离—火焰原子吸收光谱法测定水体中的铬（Ⅲ）和铬（Ⅳ）

内装活性氧化铝（碱式）和阴离子交换树脂的微型柱流动注射在线富集分离水体中的铬（Ⅱ）和铬（Ⅳ），火焰原子吸收法直接检测，微型柱可同时富集两种价态的离子，分别用１ｍｏｌ／Ｌ的ＮＨ４ＮＯ３和ＨＮＯ３洗脱Ｃｒ（Ⅳ）和Ｃｒ（Ⅲ）于喷雾器中，进样时间２５ｓ，铬（Ⅳ）和铬（Ⅲ）的富集倍数分别为１１倍和２０倍，实际水样的加标回收率在９０％～１０６％之间，分析速率为５０个样／ｈ，铬（Ⅳ），铬（Ⅲ）的检出限（３δ）分     

改性沸石填充柱在线分离富集电热原子吸收法测定水中铬(Ⅵ)及铬的形态分布

本文用溴化十六烷基三甲胺(HDTMAB)改性的天然斜发沸石微填充柱,建立了顺序注射在线分离富集电热原子吸收法测定水中Cr(Ⅵ)及铬形态分布的方法.方法测定Cr(Ⅵ)的线性范围为0.1～3.0 μg/L,检出限为0.03 μg/L,精密度为3.7%(1.0 μg/L,n=5),采样频率为16/h,当进样体积为200 μL时的富集倍率为5.6.用本法测定了标准水样GBW08608中的铬,所得结果与标准值相符.另外测定了自来水中的铬及其形态分布,加标回收率合格.     

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。     

液体样品中铬的价态和微量分析方法的研究进展

文章对液体样中铬的价态、微量铬的分离富集和分析方法进行综述,引用文献60篇。     

预富集分光光度法测定超微量铬(Ⅵ)

由于铬(Ⅵ)的强毒性,引起了人们的关注.测定铬Cr(Ⅵ)的方法文献报道较多[1～4] ,目前国家标准方法[5]是二苯碳酰二肼光度法.该法灵敏度较高,但受共存物的干扰及检出限的限制(最低检出浓度为0.004mg/L).采用液膜富集有文献报道[6] ,但液膜组成复杂,操作繁琐.采用离子色谱柱分离、富集进行铬(Ⅵ)的测定尚未见报道. 本文通过各项条件试验,确立了阴离子色谱柱分离、富集铬(Ⅵ)的最佳实验条件.     

交联壳聚糖在汞形态分析中的应用

研究了一种新型溶于水，酸，碱的交联壳聚糖在汞形态分析中的应用。以ＥＤＴＡ为络合剂，交联壳聚糖能选择性富集分离无机汞；以ＫＩ作为络合剂，交联壳聚糖同时富集甲基汞，乙基汞和苯基汞，０．４ｍｏｌ／ＬＮａＯＨ可定量洗脱苯基汞，１．０ｍｏｌ／ＬＮａＯＨ定量洗脱烷基汞，     

石墨炉原子吸收法测定高铼酸钾中杂质元素

高铼酸钾是制取高熔点金属铼的重要原料。关于高铼酸盐中杂质分析的报导甚少,一般需要预分离富集。本文在不分离富集待测元素的情况下,以标准加入法消除基体效应的影响,拟定了石墨炉原子吸收测定高铼酸钾中铜、镍、铁、锰、铝、铬的方法。     

Determination of chromium by on-line preconcentration on a poly (hydroxamic acid) resin in flow-injection atomic absorption spectrometry

A series of poly(hydroxamic acid) resins were used for the preconcentration and determination of chromium(III). Conditions were optimized for the determination of chromium(III) and its separation from multi-component mixtures. A flow manifold was developed for the on-line preconcentration and determination of chromium(III) by atomic absorption spectrometry.     

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.     

微乳相萃取分离富集-原子吸收光谱法分析铬形态

建立了一种微乳相萃取分离-石英双缝管原子捕集火焰原子吸收光谱法(STAT-FAAS)分析环境水样中铬形态的新方法。该方法中,Cr(Ⅲ)与8-羟基喹啉反应形成的疏水性配合物,经萃取进入微乳相,Cr(Ⅵ)留在水溶液中,从而实现Cr(Ⅲ)与Cr(Ⅵ)的相互分离。Cr(Ⅵ)含量的测定通过过氧化氢溶液将Cr(Ⅵ)还原为Cr(Ⅲ),按同样方法分析。实验对微乳相萃取的主要影响因素进行了优化。结果表明,经优化后实验条件为:平衡温度80℃,平衡时间10min,溶液酸度pH=9.0,NH3-NH4Cl缓冲溶液用量2.0mL,8-HQ用量0.05mmol;TritonX-100微乳液组成:m(TritonX-100):m(正戊醇):m(正己烷):m(水)=3.0:15:1.5:4.0。在此条件下,萃取的富集倍数达到25倍(50mL起初样品溶液/2mL最终测定液),线性范围为2.5～500μg/L,检出限为0.62μg/L,相对标准偏差(RSD)为3.8%(n=10,c=10μg/L)。本方法已成功地应用于电镀废水中铬形态分析。     

Slurry sampling electrothermal atomic absorption spectrometric determination of chromium after separation/enrichment by mercaptoundecanoic acid modified gold coated TiO2 nanoparticles

In this study, a novel preconcentration/separation technique based on the slurry analysis of chromium loaded on mercaptoundecanoic acid modified TiO₂ core-Au shell nanoparticles prior to its determination by electrothermal atomic absorption spectrometry was described. For this purpose, at first, TiO₂ nanoparticles were coated with gold shell and then modified with mercaptoundecanoic acid (MUA). Cr (III) was collected on the prepared sorbent by conventional batch technique. After separation of liquid phase, slurry of the sorbent was prepared and directly introduced into graphite furnace of atomic absorption spectrometry. By this way, all drawbacks due to elution procedure were eliminated. Optimum conditions for quantitative sorption and preparation of the slurry were investigated. The chromium in certificated sea-water and spiked drinking water was recovered in the range of 95% confidence level. The proposed technique was fast and simple as well as the risks of contamination and loss during elution were low. The limit of detection (3σ, N = 10) was 0.34 μg L^{− 1}.     

Determination of chromium in river waters by electrothermal atomic absorption spectrometry with preconcentration on a tantalum wire

The preconcentration of chromium on tantalum wire followed by electrothermal atomic absorption spectrometry with a tungsten tube atomizer is described. The preconcentration is accomplished by adsorbing chromium on a tantalum wire. The optimal immersion time was 3 mm. The best pH for chromium adsorption was 3. Under optimal conditions, the detection limit was 15 pg mU1 (3 x SIN). The effects on the preconcentration of chromium by large amounts of contaminants were evaluated. Even though matrix elements existed in 10(3)-10(4)-fold excess in water, the chromium absorption signal was not affected by the matrix elements. The method with preconcentration on tantalum wire was applied to the determination of chromium in river water.     

Separation and speciation of Cr(III) and Cr(VI) with Saccharomyces cerevisiae immobilized on sepiolite and determination of both species in water by FAAS

A rapid, sensitive and accurate method for the separation, preconcentration and determination of Cr(III) and Cr(VI) in water samples is described. Chromium species can be separated by biosorption on Saccharomyces cerevisiae immobilized on sepiolite and determined by flame atomic absorption spectrometry (FAAS). The optimum conditions for separation and preconcentration (pH, bed height, flow rate and volume of sample solution) were evaluated. Recovery of the chromium was 96.3+/-0.2% at 95% confidence level. The breakthrough capacity of the adsorbent was found as 228 mumol g(-1) for Cr(III). The proposed method was applied successfully to the determination of Cr(III) and Cr(VI) in spiked and river water samples.     

On-line separation and preconcentration in flow injection analysis

Various improvements in flow-injection systems involving on-line separation and preconcentration by gas diffusion, ion-exchange and liquid—liquid extraction are reviewed and their merits are discussed. On-line preconcentration systems based on gas diffusion are described for the spectrophotometric determination of cyanide, fluoride and ammonia. Different gas/liquid separation devices for hydride-generation and cold-vapour atomic absorption spectrometry (a.a.s.) are compared. Systems are outlined for on-line column preconcentration of cobalt, nickel, vanadium, beryllium and cerium for inductively-coupled plasma/atomic emission spectrometry, and for combinations of column preconcentration with hydride-generation and cold-vapour a.a.s for the determination of ultratrace selenium and mercury. An on-line liquid—liquid extraction/flame a.a.s. system capable of achieving 60-fold enhancement for lead is reported; the limit of detection is 0.02 μg ml^?.     

Direct determination of chromium(III) and chromium(VI) with ion chromatography using direct current plasma emission as element-selective detector

A method is described that utilizes direct current plasma atomic emission spectrometry as an element-selective method of detection for ion chromatographic determination of chromium(III) and chromium(VI) species. The eluting chromium-containing species are detected on the basis of the atomic emission of chromium without any species conversion. Both anion and cation separator columns give similar results when used with varying sample matrices. By employing an on-column preconcentration procedure, the detectable concentrations of the chromium species are reduced to less than 1.0 ppb. This method is applied to the determination of chromium species in human serum, natural water, and industrial process stream samples.     

Tea-industry waste activated carbon, as a novel adsorbent, for separation, preconcentration and speciation of chromium

Activated carbon was produced from tea-industry wastes (TIWAC) and employed as a low cost and effective solid phase material for the separation, preconcentration and speciation of chromium species without using a complexing agent, prior to determination by flame atomic absorption spectrometry (FAAS). The characterization of TIWAC was performed by utilizing several techniques such as Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis. The adsorption experiments were conducted in a batch adsorption technique. Under the experimental conditions, Cr(VI) adsorption amount was nearly equal to zero, however the adsorption percentage of Cr(III) was in the range of 95–100%. Therefore total chromium was determined after the reduction of Cr(VI) to Cr(III) and Cr(VI) was calculated by subtracting Cr(III) concentration from total chromium concentration. The suitable conditions for adsorption and speciation processes were evaluated in terms of pH, eluent type and volume, TIWAC concentration, adsorption and desorption contact time, etc. Adsorption capacity of TIWAC was found to be 61.0 mg g⁻¹. The detection limit for Cr(III) was found to be 0.27 μg L⁻¹ and the preconcentration factor was 50 for 200 mL of sample volume. The procedure was applied to the determination and speciation of chromium in stream, tap and sea water. Also, the proposed method was applied to total chromium preconcentration in microwave digested tobacco and dried eggplant samples with satisfactory results. The method was validated by analyzing certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and the results were in good agreement with the certified values.     

原子发射光谱分析

本文是《分析试验室》中原子发射光谱分析（AES）定期评述的继续,反映我国该研究领域在1999－2000年间所取得的进展,文献主要来自国内中文分析化学期刊,评述内容包括：概述、基础性研究、进样技术及分离富集技术、分析应用及展望5个方面,参考国外作法,有关等离子体质谱（ICP－MS）的内容在本评述中亦有反映。附参考文献256篇。