CTMAB-Peregal O存在下锌镉的FIA同时测定

混合表面活性剂CTMAB-Peregal O对Zn~(2+)和Cd~(2+)与4-(2-吡啶偶氮)一问苯二酚的配合反应有协同增敏作用。由配合反应测得Zn~(2+)和Cd~(2+)的总量,用二乙基二硫代氨基甲酸钠掩蔽Cd~(2+)后,可测得Zn~(2+)量,再由计算求得Cd~(2+)量。研究了应用连续交替注入技术流动注射光度法同时测定Zn~(2+)和Cd~(2+)的方法。Zn”和Cd~(2+)的浓度分别在0～0.6μg/g和0～1.0μg/g时符合比耳定律。相对标准偏差<1.0%,进样频率180次/h。曾用此法测定了西湖水和工业废水中的Zn~(2+)和Cd~(2+),结果满意,并初步探讨了协同增敏作用的机理。     

聚乙烯亚胺-硫脲-豆蛋白复合材料吸附铅、镉的性能

以硫脲、聚乙烯亚胺和大豆分离蛋白(SPI)为原料制备了多孔大豆蛋白复合材料(TPS)并进行表征。研究了TPS对Pb~(2+),Cd~(2+)的微柱分离富集性能。优化实验条件后,TPS对Pb~(2+),Cd~(2+)可实现定量吸附,吸附容量分别为20. 56和25. 13 mg/g,富集系数分别为200,150倍,经过100次吸附和解吸循环后TPS吸附性能未发生改变,准二级动力学方程适合描述材料对Pb~(2+),Cd~(2+)的吸附行为。建立了微柱分离富集-石墨炉原子吸收光谱测定Pb~(2+),Cd~(2+)的新方法,Pb~(2+),Cd~(2+)的检出限分别为0. 2和0. 06 ng/mL,线性范围分别为0. 02～0. 25μg/mL和0. 001～0. 015μg/mL。该方法成功应用于国标样品、鱿鱼和海水中Pb~(2+),Cd~(2+)分析。     

比光谱-导数光度法同时测定铅、镉、汞

测定食品和环境中Pb~(2+)、Cd~(2+)、Hg~(2+)的含量是较常见的分析任务.光度法同时测定Pb~(2+)、Cd~(2+)、Hg~(2+)时,常因吸收峰重叠给测定带来困难.本文阐述了利用四(4三甲铵基苯基)卟啉(TAPP)对Pb~(2+)、Cd~(2+)、Hg~(2+)同时显色,采用KI、低聚合度聚乙烯醇(PVA)增敏、增溶,在吸收光谱严重重叠情况下,采用比光谱导数和零交点法,不经分离和掩蔽,用光度法同时测定Pb~(2+)、Cd~(2+)、Hg~(2+)的含量,Pb~(2+)、Cd~(2+)、Hg~(2+)的ε_(max)分别为ε_(481.5)=4.9×10~5、ε_(457)= 7.9×10~5、ε_(444.5)=8.1×10~4(L·mol~(-1)·cm~(-1)),Pb~(2+)、Cd~(2+)、Hg~(2+)的检出限分别为4μg/L、2μg/L和10μg/L.该方法计算简便、快速.     

锌、镉、铅离子在原位铋修饰掺硼金刚石薄膜电极上的传感分析

以原位铋修饰掺硼金刚石薄膜电极为传感电极,利用阳极溶出伏安法对重金属离子Zn~(2+)、Cd~(2+)、Pb~(2+)进行同时检测分析。原位铋修饰掺硼金刚石薄膜电极可有效提高Zn~(2+)、Cd~(2+)、Pb~(2+)的溶出峰值电流。考察了p H值、扫描方式、电极硼掺杂浓度、富集电位等参数对检测分析的影响。在优化的实验条件下,原位铋修饰BDD电极对Zn~(2+)、Cd~(2+)、Pb~(2+)传感分析具有良好的特性,在10~300μg/L浓度范围内具有良好的线性度和重复性,检出限分别为0.56、0.32和0.75μg/L(S/N=3)。干扰实验结果表明,3种重金属的相互干扰较小,除Cu~(2+)外,水中常见离子对测定干扰较小。实际水样中,3种离子的回收率为92.0%~114.0%。     

铜试剂电位滴定法连续测定多种金属离子

Hassan等将光谱纯碳棒经处理制成了对铜试剂-二乙基二硫代氨基甲酸盐(DDC)敏感的电极,以此作为指示电极,NaDDC作滴定剂,在乙醇-水溶液中可分步滴定Cu~(2+)、Ni~(2+)、Zn~(2+)、Cd~(2+)等金属离子。我们发现Ag_2S晶膜电极对DDC有特别敏感的响应。以该电极为指示电极,NaDDC为滴定剂,在50-75％的乙醇溶液中可分步滴定Cu~(2+)、Ni~(2+)、Zn~(2+)、Pb~(2+)、Cd~(2+)、Th~(4+)等金属离子。滴定突跃较Hassan的更为显著。Cu~2+浓度低至2μg/ml亦能测定。用该方     

铋/石墨烯/Nafion复合膜修饰玻碳电极检测煤矸石中的镉和铅

通过滴涂法在玻碳电极(GCE)表面修饰一层多孔中空的石墨烯(GN)/Nafion(全氟代磺酸脂,NA)薄膜,然后通过电化学沉积法在GN/NA修饰的GCE表面富集Bi成功制备出铋/石墨烯/NA复合膜修饰玻碳电极(Bi/GN/NA/GCE),将所制备的Bi/GN/NA/GCE采用方波阳极溶出伏安法(SWASV)原位同时检测煤矸石中Cd~(2+)和Pb~(2+)离子,结果表明在优化实验条件下,修饰电极具有较宽的线性工作范围(Cd~(2+)和Pb~(2+)均为0.1～50μg·L~(-1)),良好的检测限(Cd~(2+)为0.08μg·L~(-1),Pb~(2+)为0.03μg·L~(-1)),样品加标回收率(Cd~(2+)为101.7%,Pb~(2+)为102.1%),且重现性好。本工作为煤矸石中重金属的检测提供了一种快速便捷方法。     

树状聚嘧胺-2-巯基苯并咪唑修饰硅胶分离富集镉

制备了树状聚嘧胺-2-巯基苯并咪唑修饰硅胶PDM-n. 0MBISG (n=1,2,3,4),利用红外光谱、扫描电镜、热重分析、元素分析和孔径与比表面分析进行表征。以PDM-n. 0MBISG(n=1,2,3,4)为填料研究其对Cd~(2+)的微柱分离富集性能。结果表明,pH8试液以3. 0 mL/min流速进样,可以实现Cd~(2+)定量吸附。PDM-n. 0MBISG (n=1,2,3,4)对Cd~(2+)的吸附容量分别为13. 37,17. 78,23. 70和29. 19 mg/g,富集系数分别达到100,150,200和200倍。准二级动力学方程可以较好的描述PDM-n. 0MBISG (n=1,2,3,4)对Cd~(2+)的吸附行为,使用100个吸附和解吸附循环后,其吸附性能未发生变化。以PDM-4. 0MBISG作为微柱填料建立了分离富集-石墨炉原子吸收光谱测定Cd~(2+)的方法,方法检出限为0. 1 ng/mL,测定Cd~(2+)的线性范围为1. 0～16 ng/mL。该方法成功应用于国标样品、鱿鱼和海水中Cd~(2+)分析。     

碳羟基磷灰石的合成对水中Cd~(2+)的去除特性研究

本文以鸡蛋壳为原料,采用凝胶-溶胶法合成碳羟基磷灰石(CHAP)并以羟基磷灰石(HAP)为对照,探讨了CHAP对水中镉(Cd~(2+))的吸附去除特性。结果表明:(1)鸡蛋壳和磷盐在75℃下反应成功合成CHAP,通过FTIR分析,合成CHAP结构具有HAP的结构特征,且掺杂了CO_3~(2-)(2)CHAP对Cd~(2+)的吸附符合Langmuir和Freundlich等温式,饱和吸附量为44.44 mg·g~(-1),高于HAP对Cd~(2+)的饱和吸附量(29.93 mg·g~(-1))48%。(3)CHAP对Cd~(2+)的吸附符合准二阶动力学方程,在60 min时吸附量达到最大值并趋于平衡。(4)当反应p H为6,温度为35℃,吸附剂用量为1.5 g·L~(-1)时,CHAP对Cd~(2+)的去除效率最佳。综上,凝胶-溶胶法合成的CHAP对水体Cd~(2+)去除效果好,成本低,可作为去除水中Cd~(2+)的低成本吸附剂,既节约资源又保护环境。     

二乙基二硫代氨基甲酸银光度法测定硅铁中砷

硅铁中砷是有害的杂质元素,砷含量高会造成硅铁粉化.ASTM方法是在锆坩埚中用Na_2O_2.熔融分解试样,经蒸馏分离后,用钼蓝光度法测定砷.该法步骤繁琐,流程冗长,较难掌握.本工作用酸溶法分解试样,二乙基二硫代氨基甲酸银(DDTC-Ag)光度法测定砷,方法简便、灵敏度高、选择性好,便于例行分析应用.对于含砷9μg·g~(-1)和23μg·g~(-1)的试样,测定的标准偏差分别为1.1μg·g~(-1)和1.7μg·g~(-1).     

新显色剂1-(2-咪唑偶氮)-2-萘酚-4-磺酸作为络合滴定指示剂的研究

本文报道了新显色剂1-(2-咪唑偶氮)-2-萘酚-4-磺酸(IANS)的物理性质、酸离解常数,并对该试剂作为EDTA络合滴定Cu~(2+)、Zn~(2+)、Pb~(2+)、Cd~(2+)、和Hg~(2+)的指示剂进行了研究,结果与二甲酚橙比较令人满意。     

银诱导大鼠肝脏金属硫蛋白的提纯与鉴定

Ｗｉｓｔａｒ公鼠经腹腔注射ＡｇＮＯ３后可诱导肝脏合成ＭＴ。经匀浆、乙醇沉降、Ｓｅｐｈａｄｅｘ－７５、ＤＥＡＥ－５２两次柱层析，可得到两个亚型。原子吸收测定结果表明：该蛋白分别含７份Ａｇ、２份Ｚｎ和２份Ｃｕ，具有与Ｃｄ５Ｚｎ２－ＭＴ并不相同的二级、三级结构。进一步研究表明，蛋白中伴随Ｃｕ和Ｚｎ的含量与所用诱发剂的种类、数量均有关，且Ｃｕ和Ｚｎ（通过ＭＴ）具有某种微妙的联系。     

Characterization and quantification of metallothionein isoforms by capillary electrophoresis–inductively coupled plasma–isotope-dilution mass spectrometry

In a new approach to the characterization and quantification of metallothionein isoforms an on-line isotope-dilution method in combination with the coupling of capillary electrophoresis (CE) to an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS) is reported. Metallothionein (MT) isoforms are separated by CE and the elements Cu, Zn, Cd, and S are detected simultaneously by use of ICP-SFMS in the medium resolution mode. On-line isotope dilution is performed by continuous introduction of an isotopically enriched, species-unspecific spike solution after the separation step. MT from rabbit liver and a further purified MT-1 isoform were quantified by determination of sulfur, and the stoichiometric compositions of the metalloprotein complexes are characterized by determination of their sulfur-to-metal ratios.     

Characterization of horse kidney metallothionein isoforms by electrospray MS and reversed-phase HPLC-electrospray MS

Pneumatically assisted electrospray mass spectrometry (ESMS) in the direct mode and as a chromatographic detection technique was developed for the characterization of horse kidney metallothionein isoforms. Direct analysis in an acidic medium showed the presence of three major and five minor isoforms, the molecular masses of which were determined. The presence of the major isoforms (two of which matched the molecular masses calculated according to the published sequences) was confirmed by complexation with Cd at pH 4.0 and the determination of the stoichiometry of the complexes formed. Reversed-phase chromatography of Cd7-MT complexes (pH 6.0) gave two signals corresponding to the MT-1A and MT-1B isoforms. A post-column acidification procedure was developed to eliminate the possibility of artefacts associated with the formation of mixed-metal (Cd, Zn) complexes during chromatography in neutral media, and to improve the accuracy of the determination of the molecular mass of MT isoforms.     

Species analysis of metallothionein isoforms in human brain cytosols by use of capillary electrophoresis hyphenated to inductively coupled plasma-sector field mass spectrometry

A new approach for the speciation of metallothioneins (MT) in human brain cytosols is described. The analysis is performed by application of a newly developed coupling of capillary electrophoresis (CE) with inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). Isoforms of metallothioneins are separated from 30-100 microliter sample volumes by CE and the elements Cu, Zn, Cd, and S are detected by use of ICP-SFMS. The extraction of cytosols is the first step in the analytical procedure. Tissue samples from human brain are homogenized in a buffer solution and submitted to ultra-centrifugation. The supernatant is defatted and the cytosol pre-treatment is optimized for CE separation by matrix reduction. The buffer concentration and pH used for capillary electrophoretic separation of metallothionein from rabbit liver were optimized. CE with ICP-MS detection is compared to UV detection. In the electropherograms obtained from the cytosols three peaks can be assigned to MT-1, MT-2, and MT-3. As an additional method, size-exclusion chromatography (SEC) is applied. Fractions from an SEC separation of the cytosol are collected, concentrated, and then injected into the CE. The detection of sulfur by ICP-SFMS (medium resolution mode) and quantification by isotope dilution have also been investigated as a new method for the quantification of MT isoforms. The analytical procedure developed has been used for the first time in comparative studies of the distributions of MT-1, MT-2, and MT-3 in brain samples taken from patients with Alzheimer's disease and from a control group.     

Analysis for metallothioneins using coupled techniques

Analytical chemistry of metallothioneins based on the coupling of a high resolution separation technique with an element or species selective detection technique is discussed. The role of size-exclusion chromatography (SEC) with on-line atomic spectrometric detection for the quantification of metallothionein fraction in cell cytosols is evaluated. Particular attention is given to the conditions for the separation of metallated metallothionein isoforms (MT-1, MT-2, MT-3) and sub-isoforms within these classes by anion-exchange and reversed-phase HPLC. Techniques for interfacing chromatography with atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP AES) and ICP mass spectrometry (MS) are assessed. The potential of electrospray (tandem) mass spectrometry for the characterization of metallothionein isoforms with respect to molecular mass and aminoacid sequence is highlighted. Perspectives for capillary zone electrophoresis (CZE), microbore and capillary HPLC with ICP MS and electrospray MS(/MS) detection for the probing of metallothioneins are discussed. Applications of hyphenated techniques to the analysis of real-world samples are reviewed.     

Characterisation of human foetal liver Zn-metallothioneins using differential pulse polarography

A study on electrochemical characterisation of three isoforms of human foetal liver Zn-metallothioneins, labelled MT-0, MT-1 and MT-2, has been performed by using differential pulse polarography (DPP). Two different peaks, attributed to two different Zn complexes with metallothioneins, have been detected. The electrochemical behaviour is similar for the three studied isoforms. Studies on the addition of Cd(2+) and Zn(2+) as well as studies as a function of pH have been carried out. The association and dissociation equilibria of metal ions with MTs are reversible in the studied pH range. The behaviour of Zn complexes in human foetal liver Zn-metallothioneins is comparable to the Cd complexes obtained using other mammalian Cd, Zn-metallothioneins, particularly as a function of pH.     

A Simple and Sensitive Method for the Detection of Trace Pb(II) and Cd(II) based on Nafion‐coated Antimony Film Electrode

Nafion‐coated antimony film electrode (NCAFE) was prepared in situ by simultaneously plated antimony with analytes, and applied to the determination of trace Pb(II) and Cd(II) in non‐deaerated solutions by differential pulse anodic stripping voltammetry (DPASV). Various experimental parameters, which influenced the response of the NCAFE to those metals, were thoroughly optimized and discussed. The results indicated that the sensitivity and resistance to surfactants at the NCAFE were remarkably improved with relative to the antimony film electrode (AFE). In the presence of 5 mg·L^?1 gelatin, the peak heights at the NCAFE showed 4‐fold enhancement for Pb and a 9‐fold enhancement for Cd over a bare AFE. Reproducibility of the sensor was satisfactory, and the relative standard deviations were 4.8% for 20 μg·L^?1 Pb and 3.2% for 25 μg·L^?1 Cd (n=15) with preconcentration time of 180 s. The determination limits (S/N=3) of this sensor were determined to be 0.15 μg·L^?1 for Pb and 0.30 μg·L^?1 for Cd with accumulation time of 300 s. The NCAFE was successfully applied to determining Pb(II) and Cd(II) in vegetable and water samples with satisfactory results.     

金属硫蛋白异构体及亚型异构体的液相色谱分离与质谱鉴别

建立了金属硫蛋白(MT)异构体及亚型异构体的色谱分离与质谱鉴别方法。将金属硫蛋白混合物通过弱阴离子DEAE Sephadex A-25离子交换柱,结合离线电感耦合等离子体质谱(ICP-MS)对锌诱导金属硫蛋白的两个异构体MT-1和MT-2进行分离和检测;利用Sephadex G-25凝胶排阻色谱柱对得到的两个金属硫蛋白异构体进行脱盐;探索脱盐后的金属硫蛋白异构体在不同色谱条件下的C18反相色谱柱上的保留行为,进而实现各个亚型异构体的分离;通过在线电喷雾质谱检测实现了对金属硫蛋白各个亚型异构体的鉴别。结果表明,通过优化色谱条件,由离子交换色谱及凝胶排阻色谱得到的金属硫蛋白各亚型异构体在酸性条件下均得到了良好的分离,质谱检测结果与前人的文献报道结果一致。该方法可使金属硫蛋白各异构体均达到最佳的分离效果。     

Separation of metallothionein isoforms of mouse liver cytosol by capillary zone electrophoresis

Metallothionein (MT) isoforms of mouse liver cytosol were separated by capillary zone electrophoresis (CZE) using a polyacrylamide-coated tube at neutral pH, samples prepared from non-treated, heat-treated, and ethanol-precipitated specimens were compared. The liver was homogenized in three kinds of media, 0.25 M sucrose containing 100 mM Tris-HCl buffer at pH 7.4 (BS), BS containing 1% ascorbic acid (BS-C), and BS containing 5 mM beta-mercaptoethanol (BS-M). Mouse liver was used 24 h after subcutaneous injection of 50 mg Zn kg(-1). In the non-treated specimen of the cytosol fraction, the MT-2 isoform was separated in all three media, while the MT-1 isoform was difficult to identify. In the ethanol-precipitated specimen, MT isoforms were separated well using either BS or BS-C. However, when BS-M was used, a small MT-2 peak was obtained the MT-1 peak could not be identified. MT-1 isoform in the heat-treated specimen was difficult to identify. In contrast, MT-2 isoform was separated well in all three kinds of media. In the non-treated specimen of the control liver cytosol, the MT-2 isoform was detected using all three media, the MT-1 peak was undetected. Based on these results, MT isoforms can be detected in the crude cytosol fraction of liver using CZE combined with a polyacrylamide-coated tube at neutral pH.     

Identification of a metallothionein in Synechococcus by capillary electrophoresis hyphenated with inductively coupled plasma mass spectrometry.

A home-made system hyphenating capillary electrophoresis with an inductively coupled plasma mass spectrometer (CE-ICP-MS) for cadmium speciation of protein-binding and free cadmium ions in solution is presented. The CE-ICP-MS interface consisted of an acrylic block with an internal volume ca. 20 microL in which a platinum electrode, a capillary column, and a connection to an ICP nebulizer were inserted. A make-up electrolyte solution containing 50 mmol L(-1) Tris-HCl buffer solution (pH 9.0) was continuously flowed through the interface to the ICP nebulizer. The separation of free Cd ions, Cd-cysteine, and Cd bounded to metallothionein (MT) isoforms from rabbit liver was carried out by capillary electrophoresis, and the analytes were detected by ICP-MS. The feasibility to isolate metallothionein compounds extracted from the cyanobacterium Synechococcus PCC7942 was demonstrated. The Cd binding proteins were induced in Synechococcus PCC7942 and further analyzed by CE ICP-MS.