新型螯合树脂在线预富集测定海水中痕量Cd

将新型螯合树脂(XAD-H2Dz)应用于微柱现场在线采样(MFS)新技术中,实现了海水样中痕量Cd的在线原位预富集和实验室中流动注射-火焰原子吸收(FI-FAAS)系统的联机测定。采样体积为5 mL和50 mL时,检出限(3σ)分别为68和6.7 ng/L;相对标准偏差(n=7)分别为2.0%和2.6%。对国家海水微量元素标准物质GBW(E)080040和实际样品(大连老虎滩区域海水以及连云港黄海水域)中镉进行分析,均获得了满意的结果。     

硫代乙酰胺键合硅胶在线选择性固相萃取火焰原子吸收测定环境样品中痕量铜

以制备的硫代乙酰胺键合硅胶为微柱填充材料,建立酸性条件(pH 1 0)下流动注射微柱选择性预富集,0.6 mol/L硫脲溶液洗脱,火焰原子吸收测定环境样品中痕量铜的方法。流动注射在线固相萃取的最佳采样流速为8.0 mL/min;最佳洗脱流速为5.0 mL/min,时间为60 s。在优化的条件下,采样体积为10和50 mL时,线性范围分别为2.0～100.0μg/L和0.5～30.0μg/L;检出限(3σ)分别为0.36和0.07μg/L;富集倍数分别为80和170;相对标准偏差分别为(n=9)3.5%和2.0%。研究了环境样品中常见阴阳离子对测定的干扰。应用于灌木枝叶样品(GBW07602)、标准模拟水样(GBW08608)样品和环境样品中铜的分离与富集,取得满意结果。     

浊点萃取富集-石墨炉原子吸收光谱法同时测定环境水样和中药中超痕量铅和镉

提出了石墨炉原子吸收光谱法同时测定环境水样和中药中超痕量铅与镉的方法.以双硫腙为络合剂,在pH 7.0时,用Triton X-114非离子表面活性剂浊点萃取富集样品溶液中痕量铅和镉.用硝酸镁和磷酸二氢铵的混合液作为基体改进剂测定铅和镉,铅和镉的检出限(3s/k)分别为0.138,0.007μg·L-1,相对标准偏差(n=7)分别为1.90%,2.08%.对于10 mL样品溶液的富集倍数分别为18.3,17.7.应用所提出的方法测定了杨树叶(GBW 07604)和小麦粉(GBW08503)国家标准样品,测定结果与标准值相符.铅和镉的加标回收率分别为97.8%,94.0%(水样);98.0%,94.0%(中药样).     

微柱流动注射同位素稀释电感耦合等离子体质谱法测定海水中的痕量铅

本文建立了用微柱流动注射与电感耦合等离子体质谱联用的同位素稀释分析方法。在优化条件下铅的检出限(3σ，n=6)为0．22ng／mL，对标准水样和加标海水的测定结果表明，方法的回收率分别为104．0％和94．8％。该法具有同位素稀释测量准确度高、操作简便的优点，能实现在线分离、富集和测定，及减少样品处理引入污染等特点，可应用于生物、环境等高盐样品中铅的在线分离测定。     

双硫腙修饰纳米TiO2分离富集石墨炉原子吸收光谱法测定水样中痕量金属离子

建立了双硫腙修饰纳米TiO2分离富集-石墨炉原子吸收光谱法测定水样中痕量镉、铬和铅的新方法,优化了纳米TiO2-双硫腙对试样中这3种痕量物质的吸附和解吸条件。结果表明,在pH 5.0时,镉、铬和铅可被定量吸附,静态饱和吸附容量分别为13.3、5.5、21.8 mg/g。吸附的各种金属离子可用5 mL 0.1mol/L的硝酸完全洗脱。该方法对Cd2+、Cr3+和Pb2+的检出限(3σ,n=11)分别为0.18、0.51、1.92 ng/L,相对标准偏差分别为2.8%、2.3%和1.0%,加标回收率为96%～101%。该方法已成功应用于环境水样中镉、铬和铅的测定。     

流动注射微柱预富集-火焰原子吸收光谱法测定海水中铅(Ⅱ)

应用流动注射技术,用D412螯合树脂微柱富集海水中的铅(Ⅱ),并与火焰原子吸收光谱法相结合测定海水中铅(Ⅱ)。20mL海水样品以3mL.min-1流量进柱,被树脂螯合吸附富集,以0.2mol.L-1乙酸铵溶液5mL淋洗柱体去除干扰物,以4mol.L-1硝酸溶液4mL为洗脱剂(流量为7mL.min-1),洗脱液直接引入火焰原子吸收光谱仪雾化器,在线检测。当海水样进样20mL时,铅(Ⅱ)测定灵敏度可提高约35倍;检出限(3s)为1.3μg.L-1。实际应用于海水样品分析,加标回收率为94.5%,测定值的相对标准偏差(n=6)为2.2%。     

固体粉末进样交流电弧法测定区域地球化学调查样品中痕量银、硼、锡、铅

采用固体粉末进样交流电弧法测定区域地球化学调查样品中的痕量银、硼、锡、铅。对实验条件进行了优化,激发电流为14 A,曝光时间为40 s。选择内标元素为锗,银、硼、锡、铅的分析线波长分别为328.07,249.77,283.99,283.31 nm;内标线波长分别为303.91,270.96,270.96,270.96 nm。分别在含量0.05~3,10~140,1~50,10~100μg/g范围内,银、硼、锡、铅含量的对数与分析线、内标线的黑度差呈良好的线性关系,相关系数分别为0.998 2,0.998 8,0.999 6,0.999 0,检出限分别为0.01,1.1,0.2,0.7μg/g。用所建方法对土壤成分分析标准物质GBW07446,GBW 07453和水系沉积物成分分析标准物质GBW 07302a,GBW 07303a,GBW 07304a进行测试,银、硼、锡、铅的测定值与标准值的对数差分别为–0.007~0.024,–0.031~–0.013,0.000~0.029,0.002~0.028,测定结果的相对标准偏差分别为7.3%~9.3%,6.0%~9.9%,6.5%~9.0%,6.5%~9.9%(n=12)。该方法操作简单、快速,环境友好,适合于区域地球化学调查样品中痕量银、硼、锡、铅的分析。     

微型柱现场预富集流动注射火焰原子吸收光谱法测定环境水样中钴

以负载8-羟基喹啉(Oxine)、二乙基二硫代氨基甲酸钠(DDTC)和吡咯啶二硫代氨基甲酸铵(APDC)三种螯合剂的活性炭为微型柱的吸附材料,采用微型柱现场采样分析技术实现了连续现场富集环境水样中痕量钴,并在实验室中采用在线解吸流动注射火焰原子吸收光谱法对吸附柱中富集的钴进行了测定.该方法用于环境水样中钴的测定,10 mL富集水样的检出限(3σ)为1.13μg·L-1,分析了3件水样中的钴,测定结果的RSD(n=6)值均小于1 %.     

在线还原富集-导数火焰原子吸收光谱法测定环境水样中铬Ⅲ和Ⅵ铬的形态

采用单阀双阳离子交换树脂微柱并联 ,设计了双路采样逆向洗脱在线分离富集系统 ,该系统与原子吸收导数测量技术相结合 ,实现了在线分离富集 导数火焰原子吸收光谱法同时测定水中Cr 和Cr ,导数仪用 2mV min档位 ,富集 1min时 ,分析速度为 6 0样 h ,测定Cr 和Cr 的特征浓度分别为 0 .44 8μg L和0 793μg L(相当于 1%导数吸收度 ) ,线性范围分别为 0～ 90和 0～ 180 μg L ;对浓度分别为 10、2 0 μg LCr 和Cr 测定的相对标准偏差分别为 2 .85 %和 2 .85 %;检出限分别为 0 .85 5和 1.71μg L ;该法对实际水样加标回收率在 94.7%～ 10 4%之间。     

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.     

Copolymers of tetrafluoroethene with chlorotrifluoroethene and with bromotrifluoroethene

Tetrafluoroethene (TFE)–chlorotrifluoroethene (CTFE) and TFE–bromotrifluoroethene (BTFE) copolymers have been synthesized by solution copolymerization over the entire range of comonomer composition. Crystallinity data are reported and first- and second-order transitions have been investigated by DSC. Glass transition temperatures of TFE-CTFE copolymers vary in a nonlinear fashion in the range defined by the homopolymers conforming best to the Johnston equation; the behavior in the TFE-BTFE system is more linear. Whereas TFE-BTFE copolymers show a steep decrease of melting temperature at higher BTFE content, due to the amorphous character of the polymers, more regular behavior was found for TFE-CTFE copolymers. Enthalpies of fusion are also reported. The results are discussed in relation to copolymer composition and structure and are compared with data on tetrafluoroethene–hexafluoropropene (FEP) fluorocarbon resins.     

Asymmetric sorbents with N-carboxymethyl-L-valine and with N-carboxymethyl-L-aspartic acid

Conclusions The asymmetric sorbents with N-carboxymethyl-L-valine with N-carboxymethyl-L-aspartic acid can be used to resolve racemates by the ligand-exchange chromatography method. Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2378–2380, October, 1976.     

Extraction with supercritical gases in coupling with thin-layer chromatography

Summary Numerous substances can be extracted from samples by supercritical gases, e.g. either carbon dioxide or nitrous oxide in the fluid condition at temperatures of 40° C and pressures between 70 and 400 bar. An apparatus for such solvent-free extraction in the analytical field is described. It is coupled directly with a receiving apparatus for subsequent thin-layer chromatography. Three examples with corresponding chromatograms show the possibilities and advantages of this new coupling procedure.

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Extraktion mit überkritischen Gasen in Kopplung mit der Dünnschicht-Chromatographie1. Mitteilung: Aufbau der Apparatur, Handhabung und Anwendung

Zusammenfassung Zahlreiche Substanzen lassen sich mit überkritischen Gasen aus Proben fraktioniert abtrennen. Als Gase dienen z.B. Kohlendioxid und Distickstoffoxid im fluiden Zustand, d.h. bei Temperaturen von 40° C und Drücken zwischen 70 und 400 bar. Für derartige lösungsmittelfreie Extraktionen im analytischen Bereich wird eine Apparatur beschrieben. Sie ist direkt mit einer Auffangapparatur zur anschließenden Dünnschicht-Chromatographie gekoppelt. An 3 Beispielen mit entsprechenden Chromatogrammen werden die Möglichkeiten und Vorteile dieser neuen Kopplungsmethode demonstriert.

     

Reactions of indole derivatives with cardioprotective activity with reactive oxygen species. Comparison with melatonin

We have previously reported on the synthesis of novel indole derivatives containing an amine-triazole moiety (1a-d, 2a-c), and their antioxidant activity on in vitro non-enzymatic rat hepatic microsomal lipid peroxidation. Some of the compounds showed protective activity against oxidative injury of ischemic myocardium. In the present paper we investigated the interactions of these derivatives with reactive oxygen species, in order to find a mechanism of their antioxidant capacity and to identify structural characteristics responsible for these properties. These interactions were compared with melatonin, which is also an indole derivative. The antioxidant profiles of the compounds were established by different in vitro protocols as follows: 1) by the interaction of the compounds with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical, 2) their scavenging effects on superoxide anions using an enzymic system of xanthine-xanthine oxidase, 3) their inhibitory effects on xanthine oxidase and 4) their ability to scavenge hydroxyl radicals by comparison with dimethyl sulfoxide (DMSO) for *OH. All compounds were found to interact with DPPH, most of them to be superoxide anion scavengers and to be strong hydroxyl radical scavengers. Derivatives 1a and 1d substituted on the nitrogen of the indolic nucleus were found to have better antioxidant properties than the reference compounds used and melatonin.     

Voltammetry with a Fluoride-Selective Electrode with Solid-Phase Reference System

Experimental results obtained in a study of the voltammetric response of an all-solid fluoride-selective electrode based on LaF₃ (Eu²⁺ 0.8 mol %), LaF₃ (Sr²⁺ 5 mol %) and CeF₃ (Sr²⁺ 5 mol %) single crystals brought in contact with Ag, Bi, and Sn metal samples are presented. The method of cathodic inversion voltammetry was applied to study the reduction of La³⁺ and Ce³⁺-cations from the rigid sublattice of solid electrolytes, which determines the threshold of the electrochemical stability of a membrane. Anodic inversion voltammetry was used to investigate the characteristics of solid-phase generation of metal fluorides at the interface between the fluoride-selective electrode and metals.     

Electrochemical sensing with electrodes modified with molecularly imprinted polymer films

This article summarises our work on the development of voltammetric sensors based on molecularly imprinted polymers. Several recognition elements and integration strategies were used:1.membranes electropolymerised at the electrode surface; 2.casting of polymeric membranes by drop-coating a solution of pre-formed polymer (polyphosphazene) and template in a low-boiling-point solvent on to the electrode surface; 3.preparation of composite membranes containing conductive material (graphite or carbon black), acrylic-type molecularly imprinted polymers (small particle size), and PVC as binder; and 4.in-situ polymerisation of a thin layer of acrylic imprinted polymer deposited on the electrode surface by spin coating.All the options evaluated offer the possibility of controlling electrode characteristics such as hydrophobic/hydrophilic character, permeability, or film thickness, which are essential for obtaining good sensor performance.     

Microfibrillated cellulose with sizing for reinforcing composites with LDPE

Microfibrillated cellulose (MFC) fibers were acylated by the sizing agent, alkenyl succinic anhydride (ASA) reagent in an aqueous medium, by simple impregnation. The chemical modification was confirmed by Fourier transform infrared spectroscopy and solid-state ¹³C NMR. All the samples were combined with low-density polyethylene and the morphology, thermal properties, mechanical properties and water absorption behavior of the ensuing composites were investigated. The chemical modification of the MFC with ASA improved the interfacial adhesion with the matrix and hence the mechanical properties of the composites while decreasing their water uptake capacity. In addition, it was shown that the degree of substitution strongly influenced the performance of the composites.     

Multielement analysis with ICP-AES-possibilities for quality control with CRMs

Summary An analysis using Certified Reference Materials (CRMs) together with routine samples is by far the best approach for quality control in multielement analysis of environmental samples. The selection of the correct CRM is thus the first important step for all reliable analysis. The chosen material should have a similar matrix, similar concentration of the element(s) of interest and a sufficient number of well-certified elements. For the analysis of samples from the Environmental Specimen Bank only a few CRMs could be successfully used. These were analyzed for a considerable period of time, together with the routine samples for quality control. The results of these analyses were compared with the certified values.