石墨炉原子吸收法测定补钙剂和补锌剂中痕量镉

探讨了用塞曼效应石墨炉原子吸收法测定补钙剂和补锌剂中痕量镉,研究了石墨炉升温程序及基体改进剂对测定的影响。测定结果表明,采用塞曼效应扣背景的方法,以5μL1.0g／L硝酸钯作为基体改进剂,能够提高镉对温度的稳定性和分析的灵敏度,用标准曲线法测定镉,回收率的平均值高达96％o     

元素在石墨炉内石墨探针表面上的原子化机理研究(Ⅰ)——镉与铝的原子化机理

自1978年B.V. L′vov提出石墨炉内探针原子化技术以来,许多作者对该技术进行了研究,并将其应用于实际样品的测定,国内亦有人作过系统的评述,但对元素在石墨探针表面上的原子化机理却报道不多。本文应用X射线衍射分析与其它一些实验,观察和研究了镉和铝在石墨探针表面上原子化过程中的形态变化,阐明了镉和铝的原子化历程。     

石墨炉原子吸收光谱法测定三氧化钨和钨酸中微量铝和镉

石墨炉原子吸收光谱法测定铝和镉的灵敏度较高,但它们受基体的影响比较严重,测定钨酸和三氧化钨中微量铝尚有文献报导,测定微量镉还未见到有关文献。本文采用国产仪器,全热解石墨管,对石墨炉原子吸收光谱法测定钨酸及三氧化钨中微量铝和镉进行了实验。选择了最佳条件,对基体元素钨及其在溶样过程中所要接触到的干扰因素进行了考查。提出了消除干扰的措施,选择了合适的溶样方法。采用悬浮液进样解决了因钨酸析出而必须化学分离的困难。样品分解后直接用标准曲线     

石墨炉原子吸收光谱法测定碘化铯晶体中铊

采用平台石墨炉原子吸收光谱法测定了碘化铯晶体中铊。研究了碘化铯对钯－硝酸镁基本改进剂中铊吸光度影响,用预混合钯－硝酸镁和样品溶液,由于在碘化物溶液中易析出金属钯而使测定结果降低。用样品溶液和基体改进剂分别加入到石墨炉中的标准加入法可得到满意的结果。     

石墨炉原子吸收法测定豆豉中铅和镉

豆豉样品经微波消解后,采用石墨炉原子吸收光谱法快速测定铅、镉。实验优化了石墨炉原子吸收光谱法的测定条件。以磷酸为基体改进剂可提高灰化温度,消除样品中的氯化钠等复杂基体的干扰。该法铅、镉的回收率分别为95.0％、94.6％,精密度（RSD）分别为8.7％和5.1％。结果表明豆豉中铅、镉含量较低。本方法简便、快速、准确,适合于实际的分析工作。     

石墨炉原子吸收法测定柑桔中痕量镉

镉在人体中主要对肝、肾和骨组织产生伤害。测定食品中镉含量是我国食品卫生标准所要求的。目前因为国内外一般采用吸光光度法、伏安法和原子吸收法测定食品中的镉,其中石墨炉原子吸收法因简便快速,应用较广,但该法基体干扰严重、重现性较差。笔者运用基体改进剂来消除该法用于柑桔中痕量镉测定时的干扰,探讨了基体改进剂种类、用量以及石墨炉升温程序等对测定的影响。     

石墨管测试性能的研究及在无焰原子吸收法测定化探样品痕量银镉铍中的应用

本文详细研究了各种石墨管的测试性能和实际应用,对各种石墨管的记忆效应,灵敏度检测限,精密度和抗酸能力进行了比较,并研究了各种石墨管对银、镉、铍的灰化和原子化温度及在样品分析中的适应性。发现不同元素应选用不同厂家的石墨管是重要的,拟定了加入基体改进剂后的直接测定程序,应用于地球化学标样中痕量银、镉、铍的测定,其结果与可用值相符。本工作对其它元素测定和石墨管种类选择,也具有普遍的借鉴作用。     

湿法消解–石墨炉原子吸收标准加入法测定土壤中的镉

土壤样品经过硝酸–氢氟酸于130℃加热回流处理后,采用石墨炉原子吸收标准加入法测定半消解样品中镉的含量。以5%氯化铵或0.1%硝酸钯作为化学改进剂,灰化温度为500℃、原子化温度为2 000℃。当标准系列吸光度在0.18以内时,镉标准溶液的质量浓度在0~3.0μg/L内与吸光度呈良好的线性,相关系数r=0.998 6,方法的检出限为0.02 mg/kg,实际样品测定结果的相对标准偏差为3.93%~5.30%(n=5)。用该法与国标方法对土壤标准样品进行测定,两种方法测定结果一致。该法快速、简便,适用于土壤中镉含量的快速检测。     

钯－硝酸镁基体改进剂石墨炉原子吸收光谱法测定六味地黄丸中锡

本实验建立了钯－硝酸镁基体改进剂石墨炉原子吸收光谱法测定六味地黄丸中锡的方法。研究了基体改进剂的加入方式对测定的影响。方法的相对标准偏差为２．５％，回收率在９０％～１１０％之间，检出限为０．３ｎｇ／ｍＬ。本方法可用于中成药中锡的测定。     

快速石墨炉原子吸收法测定金属钴和海水中微量镉

报道了用热解石墨涂层管快速无干扰直接测定金属钴中镉的方法,并提出以草酸为基体改进剂降低背景吸收直接测定海水中微量镉.     

Pd(0.213)Cd(0.787) and Pd(0.235)Cd(0.765) structures: their long c axis and composite crystals, chemical twinning, and atomic site preferences

We present single-crystal studies of Pd(0.213)Cd(0.787) and Pd(0.235)Cd(0.765), synchrotron powder studies of Pd(1-x)Cd(x), 0.755> or =x> or =0.800, and LDA-DFT and extended Hückel (eH) calculations on these or related phases. The two single-crystal structures have a, b, and c axis lengths of 9.9013(7), 14.0033(10), 37.063(24) and 9.9251(3), 14.0212(7), 60.181(3) A, respectively and they crystallize in the space groups Ccme and F2mm, respectively (solved as (3+1)-dimensional crystals their most convenient superspace group is Xmmm(00gamma)s00). The structures have two different structural components each with their own separate axis parameters. Powder data shows that the ratio of these separate axes (S/L) varies from 1.615 to 1.64, values near the golden mean (1.618). For Pd(0.213)Cd(0.787), different Pd and Cd site occupancies lead to variation in the R factor from 2.6-3.6 %. The site occupancy pattern with the lowest R factor (among the 26 820 variants studied) is the exact site occupancy pattern predicted by LDA-DFT parameterized eH Mulliken charge populations. The phases can be understood through a chemical twinning principle found in gamma-brass, the parent structure for the above phases (a relation with the MgCu(2) Laves phase is also noted). This twinning principle can be used to account for Cd and Pd site preferences. At the same time there is a clean separation among the Cd and Pd atoms for the two separate chain types at height b=0 and 1/2. These results indicate that Cd:Pd stoichiometry plays a role in phase stability.     

Determination of cadmium in hair and blood by tungsten coil electrothermal atomic absorption spectrometry with chemical modifiers

Three chemical modifiers ((NH(4))(2)HPO(4), NH(4)H(2)PO(4), and Pd as Pd(NO(3))(2)) were evaluated for the determination of Cd in acid-digested solutions of hair and blood using electrothermal atomic absorption spectrometry in a tungsten coil atomizer (TCA). All modifiers caused some thermal stabilization of Cd when compared to the behavior observed in nitric acid medium. The best effects were observed in 15 mug ml(-)(1) Pd medium; the characteristic mass of Cd was 0.3 pg and the method detection limits were 0.009 mug g(-)(1) in hair and 0.2 mug l(-)(1) in blood. In addition to a slight thermal stabilization effect, Pd also increased the sensitivity for Cd by ca. 40% and the tungsten coil lifetime by 20% (i.e. from 300 to 360 heating cycles), reduced background signals, and eliminated condensed phase interferences caused by concomitants. The accuracy (3.2% as mean relative error in the Pd modifier) was checked for the determination of Cd in acid-digested solutions of certified reference materials of human hair and blood and by recoveries of Cd in spiked hair and blood samples by both TCA and a graphite furnace procedure. All results obtained in chemical modifiers are in agreement at a 95% confidence level.     

Determination of Ag, Cd, Pb, Zn and Pd in sea-water by thermal-ionization isotope-dilution mass spectrometry

The concentrations of Ag, Cd, Pb, Zn and Pd in sea-water have been determined by thermal-ionization isotope-dilution mass spectrometry. The concentrations found, in ng/kg, were 0.6 +/- 0.4 Ag, 1.9 +/- 0.4 Cd, 18 +/- 8 Pb, 30 +/- 8 Zn and < 4 Pd. These levels are lower than some reported previously. Determination of Pd in sea-water is reported for the first time.     

Cd(II), Zn(II), and Pd(II) complexes of an isoindoline pincer ligand: consequences of steric crowding

The sterically crowded isoindoline pincer ligand, 6'-MeLH, prepared by condensation of 4-methyl-2-aminopyridine and phthalonitrile, exhibits very different reaction chemistry with Cd2+, Zn2+, and Pd2+. Three different ligand coordination modes are reported, each dependent upon choice of metal ion. This isoindoline binds to Cd2+ as a charge-neutral, zwitterionic, bidentate ligand using imine and pyridine nitrogen atoms to form the eight-coordinate fluxional complex, Cd(6'-MeLH)2(NO3)2. In the presence of Zn2+, however, loss of a pyridine arm occurs through solvolysis and tetrahedrally coordinated complexes are formed with coordination of pyrrole and pyridine nitrogen atoms. Reaction with Pd2+ produces the highly distorted, square planar complex Pd(6'-MeL)Cl in which a deprotonated isoindoline anion coordinates as a tridentate pyridinium NNC pincer ligand.     

The use of chemical modifiers in the determination of cadmium in sewage sludge and tin in PVC by solid sampling-graphite furnace atomic absorption spectrometry

The effects of NH₄H₂PO₄ and Pd as chemical modifiers in SS-GFAAS are studied in the determination of Cd in sewage sludge and of Sn in PVC samples. Whereas for Cd both modifiers act equally well whether Cd is in solution or in the solid sample, the effect of Pd on tin is different. To make the Pd modifier as effective on Sn in PVC as on Sn in solution a two-step pyrolysis must be introduced into the temperature programme. It is also shown that the contribution of the application of chemical modifiers to the final imprecision of the determination is negligible compared to that introduced by the sample inhomogeneity.     

Adsorption properties of the double-imprinted electrospun crosslinked chitosan nanofibers

Pb(II)-Cd(II) double-imprinted electrospun crosslinked chitosan nanofibers (Pd/Cd-DIECCNs) were prepared by combining electrospinning and ion-imprinting methods, which showed excellent adsorption capacity for both Pb(II) and Cd(II).     

Polarographic study of the dipropyldithiophosphinate complexes of Pd(II), Pb(II), Cd(II), and Zn(II) ions

The complexes of the dithiophosphinic acids with Pd(II), Pb(II), Cd(II), and ZN(II) in a toluene-ethanol medium produce single polarographic waves. The half-wave potential is a linear function of the ligand concentration. The stabilities of these chelates, which are characterized by a sulphur-metal bond, are in the order: Pd(II) > Pb(II) > Cd(II) > Zn(II).     

The production of 103Pd and 109Cd from a proton irradiated tandem natAg/natAg targets

This paper describes a new method for the production of ¹⁰³Pd and ¹⁰⁹Cd using the 66 MeV proton beam of iThemba LABS on a tandem natural silver target (Ag/Ag). The radiochemical separation of the Pd radionuclides (¹⁰³Pd, ¹⁰⁰Pd) from the bulk ^natAg was done using a Chelex-100 chelating resin column. The recovery of ¹⁰³Pd from the irradiated ^natAg target was found to be >98 % without any Ag or Rh impurities detected. The radiochemical separation of ¹⁰⁹Cd from the bulk ^natAg target was done by the precipitation of Ag ions by Cu followed by the separation of ¹⁰⁹Cd, traces of Ag, Cu²⁺ and Rh using a AG1-X10 anion exchange resin column. The recovery yield of ¹⁰⁹Cd was >99 % without any Ag or Rh impurities detected.     

Attack of cadmium(II) and palladium(II) on cis-(R,S)-[Pd(egta)]2−: coordination rearrangements facilitated by pendant carboxylates

Cd(H2O)2+6–8 reacts with cis-(R, S)-[Pd(egta)]2– producing equimolar amounts of [Cd(egta)]2– and [Pd2(egta)Cl2]2–. The progress of the reaction and products have been followed by recording 1H- and 13C-n.m.r spectra as a function of time. The PdII released in forming [Cd(egta)]2– is thousands of times more reactive than CdII, and intercepts another [Pd(egta)]2– to form the 2:1 complex [Pd2(egta)Cl2]2–; the 2:1 complex is not attacked by CdII. The role of pendant carboxylates below the PdN2O2 plane of cis-(R, S)-[Pd(egta)]2– in supplying a site for docking of an incoming CdII or PdII centre, and in leading the metal near the lone pair of rupturing Pd–N bond of [Pd(egta)]2–, or simply by increasing the residence time of CdII or PdII nearby to accelerate the number of collisions between the ruptured N-base and external metal ions, is described. Although mixed-metal [Cd(Pd)(egta)] intermediates are required for the reaction, no such species achieves a detectably large enough concentration to be seen by 1H-n.m.r. The observed spectra are the sum of the reactant, [Pd(egta)]2–, and products, [Cd(egta)]2– and [Pd2(egta)Cl2]2–, throughout the time-dependent change.     

Determination of cadmium and lead in biological samples by Zeeman ETAAS using various chemical modifiers

The electrothermal atomic absorption spectrometric determination of cadmium and lead in biological certified reference materials (CRMs) has been carried out by using NH(4)H(2)PO(4), Ni, Pd, Ni+NH(4)H(2)PO(4), Pd+NH(4)H(2)PO(4) and Ni+Pd+NH(4)H(2)PO(4) as chemical modifiers. A comprehensive comparison was made among the modifiers in 1% Triton X-100 plus 0.2% nitric acid as diluent and without modifier. Zeeman background correction and graphite tubes inserted with platforms were used. Comparison was made in terms of pyrolysis and atomization temperatures, atomization and background absorption profiles. Ni+Pd+NH(4)H(2)PO(4) modifier mixture was found to be preferable for the determination of Cd and Pb. Pyrolysis temperatures of analytes were increased up to 900 degrees C for Cd and 1250 degrees C for Pb by using Ni+Pd+NH(4)H(2)PO(4) in 1% Triton X-100 plus 0.2% nitric acid diluent solution. Biological CRMs were analyzed to verify the accuracy and precision of this method. Depending on the biological sample type, the percent recoveries were increased from 62 to 102% for Cd and from 58 to 106% for Pb by using the proposed modifier mixture. The detection limits of Cd and Pb were found to be 0.04, 0.92 mug l(-1), respectively.