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61.
《Electroanalysis》2003,15(17):1369-1376
Silver‐gold alloy electrodes have been studied for the purpose of the quantitative determination of heavy metals by subtractive anodic stripping voltammetry, (SASV). The results have been compared with those obtained with the silver and gold electrodes. The 50/50 a/o Ag/Au alloy electrode is the most suitable for quantifying thallium in the presence of lead and cadmium. The separation of its peak from those of lead and cadmium is 200 mV, which is about twice the separation obtained on the pure metal electrodes and is also better than on mercury. The silver electrode is suitable for the simultaneous determination of thallium, lead and cadmium. The peaks of lead and cadmium overlap on the 50/50 alloy. Pure silver or pure gold can be used for simultaneous quantification of these two metals. The use of gold for quantifying lead and cadmium is more limited because the peak potential of cadmium is shifted in the negative direction as its concentration increases and at [Cd2+]>200 nM, the two peaks merge. SASV enables correction for background currents and is of utmost importance for obtaining well‐defined peaks. The peaks of lead, cadmium and thallium appear over a relatively narrow potential range (ca. 200 mV) on all the electrodes presented in this work. For this reason, the quantifying of a peak is based on the derivative at the inflection point of only one of its branches (ascending or descending). All SASV measurements were carried out without removal of oxygen. 相似文献
62.
A PVC membrane electrode for lead ions based on 5,5′-dithiobis-(2-nitrobenzoic acid) as membrane carrier was prepared. The electrode exhibits a Nernstian response for Pb2+ over a wide concentration range (1.0×10−2–4.0×10−6 M). It has a relatively fast response time and can be used for at least 3 months without any divergence in potentials. The proposed electrode revealed good selectivities for Pb2+ over a wide variety of other metal ions and could be used in a pH range of 2.0–7.0. It was used as an indicator electrode in potentiometric titration of lead ions and in direct determination of lead in water samples. 相似文献
63.
Pb2(OH)2[p‐O2C‐C6H4‐CO2]: Synthesis and Crystal Structure Single crystals of Pb2(OH)2[p‐O2C‐C6H4‐CO2] ( 1 ) were obtained by hydrothermal reaction of terephthalic acid and PbCO3 at 180 °C (10 days). 1 crystallizes in the monoclinic space group P21/c with Z = 2 (a = 1115.6(2) pm, b = 380.10(4) pm, c = 1141.3(2) pm, β = 93.39(1)°, V = 0.4831(1) nm3). The crystal structure is characterized by ladder‐type Pb(OH)3/3 double chains, which are connected to a three‐dimensional framework by terephthalate dianions. 相似文献
64.
Jennifer S. Forrester Jennifer S. Zobec Erich H. Kisi 《Journal of solid state chemistry》2004,177(10):3553-3559
The pressure-less sintering behavior of PbTiO3 powders synthesized by mechanical alloying TiO2 and PbO was investigated using dilatometry and Rietveld refinements of X-ray diffraction patterns. As-synthesized, the powders are nanocrystalline with a mean particle size of 20 nm. Pressure-less sintering in the range 500-1050°C gives single phase ceramics with densities of 85-90% and crystallite sizes in the range 80-400 nm. Cracking due to the paraelectric-ferroelectric phase transition was not observed in samples sintered below 700°C due to the small crystallite size whereas macroscopic cracks formed in samples sintered above 700°C. Rietveld analysis indicates the formation of Pb vacancies in samples sintered and held for 24 h at intermediate temperatures (600-1000°C) which gives some insight into the mechanism of Pb loss and second phase formation in this system. 相似文献
65.
《Electroanalysis》2003,15(19):1561-1565
A highly selective membrane electrode for the determination of ultratrace amounts of lead was prepared. The PVC membrane electrode based on 2‐(2‐ethanoloxymethyl)‐1‐hydroxy‐9,10‐anthraquinone (AQ), directly coated on graphite, exhibits a good Nernstian response for Pb(II) ions over a very wide concentration range (1.0×10?7–1.0×10?2 M) with a limit of detection of 8.0×10?8 M. It has a fast response time of ca. 10 s and can be used over a period 2 months with good reproducibility (SD=±0.2 mV). The electrode revealed a very good selectivity respect to common alkali, alkaline earth, transition and heavy metal ions and could be used in the pH range of 3.5–6.8. It was used as an indicator electrode in potentiometric titration of lead ions with chromate and oxalate, and in indirect determination of lead in spring water samples. 相似文献
66.
Solvent extraction of a mixture of PbII, MnII, FeIII, CoII, NiII and CdII in aqueous perchlorate medium by a phosphorylated hexahomotrioxacalix[3]arene (calix‐3) in dichloromethane shows a significant selectivity towards lead ions. The ligand can also be incorporated into a membrane to provide a new lead ion‐selective electrode (PbII‐ISE). A plasticized PVC membrane containing 30% PVC, 53.5% ortho‐nitrophenyloctylether (NPOE), 4.5% sodium tetraphenylborate (NaTPB) and 12% ionophore was directly coated on a graphite rod. This sensor gave a good Nernstian response of 29.7 ± 0.7 mV decade?1 over a concentration range of 1 × 10?8 – 1 × 10?4 M of lead ions, independent of pH in the range 3‐7, with a detection limit of 0.4 × 10?8 M. The dynamic response time of the electrode to achieve a steady potential was very fast and found to be less than 7 s. The selectivity relative to Ag+, NH4+, Li+, Na+, K+, Ca2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Fe3+, La3+, Sm3+, Dy3+, Er3+, Y3+ and Th4+ was examined. The electrode exhibits adequate stability with good reproducibility (with a slope of 29.6 ± 1.5 mV for 8 weeks). The characteristics of the sensor are compared with those of a tetraphosphorylated calix[4]arene (calix‐4) based PbII‐ISE, reported recently. The electrode was successfully used as an indicator electrode for a potentiometric titration of a lead solution using a standard solution of EDTA. The applicability of the sensor for lead ion measurements in various synthetic samples was also investigated. 相似文献
67.
A new flow injection (FI) system for the determination of Pb(II) at trace level with a preconcentration step and spectrophotometric detection is proposed. It is based on preconcentration of lead ions on chitosan and dithizone-lead complex formation in aqueous medium (pH 9). The chemicals and FIA variables influencing the performance of the system were optimized and applied to the determination of lead in natural, well, and drinking water samples. It is a simple, highly sensitive, and low cost alternative methodology. The method provided a linear rage between 25 and 250 μg l−1, a detection limit of 5.0 ng ml−1 and a sample throughput of 15 h−1. The obtained results of spiked samples are in good agreement between the proposed method and ICP-AES. 相似文献
68.
杯芳烃修饰玻碳电极吸附溶出伏安法测定微量铅 总被引:7,自引:0,他引:7
研究了以杯芳烃衍生物修饰玻碳电极,以其吸附溶出伏安法测定微量铅。对富集时间、铅的浓度、支持电解质、样品溶液pH值及部分离子干扰等进行了实验。实验发现以氢氧化钠溶液处理修饰电极可提高测定灵敏度,经过优化处理后,线性范围和检出限分别为5.0×10-7~1.0×10-5mol/L和1.0×10-8mol/L。应用本法对合成水样进行了测定,结果满意。本文还对吸附溶出机理进行了讨论。 相似文献
69.
Zhi-Yong Huang Zhi-Xia Zhuang Xiao-Ru Wang Frank S.C. Lee 《Analytica chimica acta》2004,508(2):239-245
Isotope dilution analysis method coupled with flow injection and inductively coupled plasma mass spectrometry (ID-FI-ICP-MS), enabled trace lead concentration in seawater to be determined and the high salt concentration in the matrix, such as Na+, Ca2+ and Mg2+, to be removed on-line. The operational parameters of the FI system including pH for the chelating reaction, concentration of 8-hydroxyquinoline-5-sulfonic acid (8-HQS), sample loading time and injection speed, washing time and speed, eluting acid concentration and eluting speed, and instrumental parameters for ICP-MS were optimized and selected. Accurate results could be achieved because the isotope ratios required can be precisely measured in the range of the eluting peak by means of ID-FI-ICP-MS. The 3σ detection limit was 0.204 ng ml−1. The trace lead concentration of seawater in south Xiamen, China was 0.988 ± 0.039 ng ml−1. The recoveries of spiked Pb standard in seawater and standard reference water (GBW 08607) were 97.9 and 101.0%, respectively, with a relative standard deviation of 0.98%. This method can be used to determine trace lead concentration in high salt matrix samples, and is especially useful when the eluting peaks do not have a Gaussian-distribution. 相似文献
70.
Diego R. Pérez Susana H. Tarulli Oscar V. Quinzani Dr. Jorge Dristas Ricardo Faccio Leopoldo Suescun Alvaro W. Mombrú 《无机化学与普通化学杂志》2007,633(7):1066-1073
Four new lead(II) thiosaccharinate complexes: [Pb(tsac)2H2O] (1) (tsac: thiosaccharinate anion), [Pb2(tsac)4(py)4] (2) (py: pyridine), [Pb(tsac)(o‐phen)2](tsac)·CH3CN (3) (o‐phen: 1,10‐phenantroline), and [Pb(tsac)2(bipy)] (4) (bipy: 2,2′‐bipyridine) were prepared. The infrared and electronic spectra as well as the thermal analysis of all the compounds were recorded and discussed. The thiosaccharinate anion acts in three different coordination forms, one of then reported for the first time. The crystal structures of complexes 2 and 3 have been determined by single crystal X‐ray diffractometry. In complex 2 , two monomeric moieties are joined together forming a symmetric bis‐μ‐sulphur bridged dimer by interaction of two lead(II) atoms through the exocyclic sulphur atoms of two thiosaccharinate ligands. The seven‐fold coordination sphere of each lead atom is completed by two pyridine nitrogen atoms and by another sulfur and two nitrogen atoms of the thiosaccharinate anions. In complex 3 , the lead(II) atom is coordinated by four nitrogen atoms of two 1,10‐phenantroline molecules and by the sulfur and nitrogen atoms of one thiosaccharinate ion. The second anion has an electrostatic interaction with the nucleus. 相似文献