Sandwich techniques in flow-injection analysis : Part 2. Simultaneous Determination of Iron(II) and Total Iron

Samples (1500 μl) are inserted between zones of water and ascorbic acid solution with subsequent addition of 1,10-phenanthroline at pH 5.0. The signal provides a plateau region corresponding to Fe(Il) followed by a peak corresponding to total iron. The proposed system allows up to 90 injections per hour. Linear working ranges are 0.1–9 and 0.3–12 mg l^?1 Fe(II) and total iron, with relative standard deviations of < 0.6 and 1.2%, respectively. Results obtained for various ground waters agree well with those obtained by a standard method.     

Heterogeneous samples in flow-injection systems : Part 1. Whole Blood

It is shown that the direct analysis of heterogeneous samples by non-steady state flow methods is associated with error because of undefined dilution and dispersion. This problem is examined theoretically and confirmed experimentally on determinations of pH and CO₂ in whole blood. It is also shown that microbubbles attached to the surface of a microelectrode or CHEMFET can substantially reduce the precision of the results.     

Polarography of tin(II) chloride in acetonitrile

Polarographic and spectrophotometric data show that tin(II) chloride is a weak electrolyte in dilute acetonitrile solutions. The dominant species, SnCl₂, exists in a labile equilibrium with the ions SnCl⁺ and SnCl₃^- Oxidation and reduction of these ionic species is responsible for all observed polarographic plateaux. The dichloro—tin(II) molecule is shown to be a good acceptor species in acetonitrile solution, readily forming 1:1 complexes with ligands such as 4-picoline N-oxide.     

Electrochemical reduction of S-oxides of diphenyl disulfide: Part II. Polarography in aqueous ethanol

In 50% ethanol the polarographic reduction of the S-oxides of diphenyl disulfide results in a fission of the sulfur-sulfur bond. Diphenyl disulfone is reduced by 2 electrons per molecle with benzenesulfinate ion as reduction product and gives rise to one polarographic wave. In the polarograms of phenyl benzenethiolsulfonate as well as phenyl benzenethiolsul-finate several waves appear due to the intermediate formation of a mercury compound, which is strongly adsorbed at the mercury electrode. Under polarographic and coulometric conditions the thiolsulfonate is reduced by 2 electrons in all with benzenesulfinate ion and thiophenol as reduction products. The total limiting current of the thiolsulfinate corresponds to a reduction by 4 electrons whereas 3 electrons per molecule are exchanged in coulometric experiments at a Hg-pool with thiophenol as the main reduction product.     

Iron Interference in the Measurement of Selenium in Whole Blood,Plasma and Serum by Graphite Furnace Atomic Absorption

Abstract

Selenium is considered to be a trace element and the determination of diagnostic levels are most conveniently measured in blood, plasma or serum in humans and animals. The approach that is taken varies according to laboratory preferences. One such method involves the use of Graphite furance Atomic Absorption Spectroscopy (GFAAS). The simplicity of diluting the sample followed by direct determination without further preparation is the most attractive characteristic of this method, coupled with good sensitivity. Proper precautions must be taken however, including that of choosing the proper instrumental parameters for the analysis. If deuterium background correctiopn is used then then analyses should be carried out at the 204.0 nm line of Selenium. By using a matrix modifier consisting of Cu/Mg, deuterium background correction and off the wall of the graphite tube atomization, the determination of the analyte was demonstrated to be possible at the mentioned wavelength, free from iron interference present in the samples.     

微型HPLC-固定化酶柱后反应器-电化学检测法测定血清和全血中的葡萄糖

提出了用Ni(Ⅱ)处理10μm强酸型阳离子交换剂Partisil-10SCX再吸附葡萄糖氧化酶以制备固定化酶的新方法。酶的吸附和固定化酶的活性较一般的物理吸附有明显的改善。由此制得的固定化酶柱后反应器接入微型高效液相色谱-电化学检测体系进行了血清和全血中葡萄糖含量的测定,并实现了葡萄糖和尿酸的同时检测。     

Polarography of cadmium(II) in presence of substituted alkanolamines

A study has been made of the effect of an irreversibly adsorbed iodide layer on the anodic oxidation of formic acid at a platinized platinum electrode. It is shown that, in the presence of the preadsorbed iodide layer, the oxidation process obeys the following rate expression, i=nF k^→c^α g(θ_I) exp(α_anFφ_r/RT where α≈0.75 and α_an≈0.5. This is explained in terms of the following rate-determining step, (HCOOH)_ads→C_*OOH+H⁺+e and involves the adsorption of formic acid on the iodide covered surface. A strong catalytic effect of the iodide layer is observed; the function g (θ_I) passes through two maxima at θ_I values of 0.15 and 0.53. It is suggested that these effects arise from a coverage-dependent variation of bond strength between the adsorbed iodide and platinum.     

Polarography of uranium(VI) and lead(II) complexes with l-glutamine

The complexes of uranium(VI) and lead(II) with 1-glutamine were investigated polarographically. For uranium(VI), the complexes UO(2)G(+2), UO(2)G(2)(+2) and UO(2)(OH)Ga(2)(+) were identified at pH < 2.5, pH 2.5-4.1 and pH 4.1-5.2 respectively. With lead(II), complexes PbG(+2), Pb(OH)G(+) and Pb(OH)G(2)(+) were formed at pH 2.0-5.0, pH 5.0-7.0, and pH 7.0-8.5, respectively. The concentration dissociation constant of Pb(OH)G(2)(+) was found to be pK(c) = 10.16 +/- 0.04 at ionic strength 0.6.     

The electrophilic reactions of pentacyanonitrosylferrate(II) with hydrazine and substituted derivatives. Catalytic reduction of nitrite and theoretical prediction of eta(1)-, eta(2)-N(2)O bound intermediates

The electrophilic reactivity of the pentacyanonitrosylferrate(II) ion, [Fe(CN)(5)NO](2)(-), toward hydrazine (Hz) and substituted hydrazines (MeHz, 1,1-Me(2)Hz, and 1,2-Me(2)Hz) has been studied by means of stoichiometric and kinetic experiments (pH 6-10). The reaction of Hz led to N(2)O and NH(3), with similar paths for MeHz and 1,1-Me(2)Hz, which form the corresponding amines. A parallel path has been found for MeHz, leading to N(2)O, N(2), and MeOH. The reaction of 1,2-Me(2)Hz follows a different route, characterized by azomethane formation (MeNNMe), full reduction of nitrosyl to NH(3), and intermediate detection of [Fe(CN)(5)NO](3)(-). In the above reactions, [Fe(CN)(5)H(2)O](3)(-) was always a product, allowing the system to proceed catalytically for nitrite reduction, an issue relevant in relation to the behavior of the nitrite and nitric oxide reductase enzymes. The mechanism comprises initial reversible adduct formation through the binding of the nucleophile to the N-atom of nitrosyl. The adducts decompose through OH(-) attack giving the final products, without intermediate detection. Rate constants for the adduct-formation steps (k = 0.43 M(-)(1) s(-)(1), 25 degrees C for Hz) decrease with methylation by about an order of magnitude. Among the different systems studied, one-, two-, and multielectron reductions of bound NO(+) are analyzed comparatively, with consideration of the role of NO, HNO (nitroxyl), and hydroxylamine as bound intermediates. A DFT study (B3LYP) of the reaction profile allows one to characterize intermediates in the potential hypersurface. These are the initial adducts, as well as their decomposition products, the eta(1)- and eta(2)-linkage isomers of N(2)O.     

Polythiolated complexes. Part 2(1). Palladium(II) and platinum(II) derivatives of polyfluorophenylthiolates

Summary The preparation and characterization of the new thiolate complexes [M(SR)₂(SEt₂)₂] (M=Pt, R=C₆F₅ orp-C₆HF₄) and [M(SR)₂]_n (M=Pd, R=C₆F₅,p-C₆HF₄ orp-C₆H₄F; M=Pt, R=p-C₆H₄F) is discussed. The tendency to form polymeric, rather than monomeric species, varies as follows: Pd>Pt; C₆H₄F>C₆HF₄> C₆F₅. [Pt(SC₆F₅)₂(SEt₂)₂] has atrans square planar coordination.     

2-(α-pyridyl)thioquinaldinamide: a novel fluorimetric reagent in inorganic trace analysis. : Part 2. A simple selective determination of selenium(IV) at Ultratrace Levels

The very sensitive fluorimetric determination of selenium(IV) is based on its oxidation of the non-fluorescent 2-(α-pyridyl)thioquinaldinamide in slightly acidic solution (0.05–0.15 M sulphuric acid). The excitation and emission wavelengths are 350 nm and 500 nm, respectively. Linear calibration graphs are obtained for different ranges of selenium concentration between 0.01 ng ml^?1 and 0.5 μg ml^?1. Over sixty ions either do not interfere or can be masked in the determination of 1 ng ml^?1 Se(IV). The method is applied successfully to various synthetic mixtures and to a native sulphur sample. The reaction is fast and the fluorescent system is stable for 24 hours.     

单扫描极谱法测定注射液及血清中维生素K1

建立了维生素K1的极谱测定方法.在0.05 mol·L-1 NH4Cl-NH3(pH 8.58)缓冲溶液中,维生素K1可产生一极谱还原峰,峰电位Ep为-0.39 V ;其二阶微分峰峰电流ip″与维生素K1的浓度在1.1×10-7 ～2.2×10-5 mol·L-1范围内呈线性关系,相关系数r=0.998 6(n= 9 );方法的检出限为4.0×10-8 mol·L-1.13次平行测定2.2×10-5 mol·L-1维生素K1还原波二阶导数峰峰电流ip″的相对标准偏差(RSD)为1.83%.本法可直接用于注射液及血清中维生素K1含量的测定.     

1,8-dihydroxyanthraquinone-Mg(II) complex: II. Spectrophotometric study. Determination of Mg(II)

The 1,8-dihydroxyanthraquinone (1,8-DHAn) shows a colored and fluorescent reaction with the ion Mg(II) in a hydroalcoholic and ammonical medium.In the present work we have studied spectrophotometrically the 1,8-DHAn-Mg(II) complex in a hydroethanolic and ammonical, 8 × 10^?4M medium. We found that the complex shows a maximum absorbance at 510 nm, and obeys a 1:1 stoichiometry with log K of 4.08.We propose a new method for the spectrophotometric determination of Mg(II) which is valid for concentrations between 0.25 and 2.00 ppm, and yields an error of 1.32%.     

Direct Determination of Lead in Whole Blood Using Electrothermal Vaporization Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

A carbon rod atomizer was used for sample introduction into a commercial inductively coupled plasma for the determination of lead in whole blood. Samples of known lead concentration were either treated with Triton-X or nitric acid or diluted 1+5 with distilled water and analyzed by comparison against graphs obtained using aqueous solutions and using the standard additions method. Both approaches produced similar results indicating no appreciable matrix influence. The Pb concentration values obtained were in close agreement with those previously determined by ETA-AAS, Delves′ cup-FAAS and anodic stripping voltammetry. Signal integration and careful selection of the measurement period were critical to obtain accurate results. Derived concentrations were shown to be essentially independent of the heating rate of the vaporization unit and the length of tubing used to transport the material into the plasma. Using a 1 μg ml^?1 lead aqueous standard, a signal to background ratio of 5.5 was obtained under optimized conditions. Relative standard deviations of the blank and the analytical signal were 0.2 and 1.8%., respectively. An aqueous solution detection limit of 0.007 μg ml^?1 was calculated for lead.     

高效液相色谱法测定血中苯妥英浓度

A high performance liquid chromatographic method for the quantitative analysis of phenytoin(PHT) inhuman plasma or whole blood is described. After a onestep extraction of PHT and internal standard withethyl acetate from human plasma or whole blood,samples were chromatographed on a Spherisorb-C(18) columnwith a mobile phase of methanol-water-tetrahydrofuran(45/55/5,V/V/V)at a flow rate of 0. 3mL/min. Theeluant was monitored at 210nm.     

Components of the Net Current in Differential Pulse Polarography. Part 2. Kinetics and Adsorption

Components of the net response in differential pulse polarography were studied theoretically, assuming gradually changing electrode rate constant or strength of the reactant adsorption. The difference between the maximum potential of the peak component and the half‐wave potential of the wave component appear as an important parameter. From its value, the electrode rate constant can be calculated even when the standard potential is not known. In a reversible process, effects of the reactant adsorption on the mentioned separation are less pronounced. The results were compared with experimentally obtained effects. For deeper insight into the applicability of this approach, additional experimentally obtained polarograms (that reflect different potential/timing parameters or changing character of the electrode process) should be studied in terms of their components.     

Simultaneous Determination of Cd(II), Cu(II), Pb(II) and Zn(II) in Human Plasma by Potentiometric Stripping Analysis

In this paper, Potentiometric Stripping Analysis (PSA) was simultaneously used to determine the concentrations of trace metals (Zn, Cd, Pb and Cu) in human plasma. The metal ions were concentrated as their amalgams on the glassy carbon surface of a working electrode that was previously coated with a thin mercury film and then stripped by a suitable oxidant. The selection of the experimental conditions was made by using the experimental‐designed methodology. The optimum conditions of the method includes a 0.2 M HAc‐NaAc buffer mixture (pH 4.5) as supporting electrolyte, and an electrolysis potential of‐1220 mV. The limits of detection (LOD) were obtained 1 μg L^?1 for Zn(II) and Pb(II), 0.5 μg L^?1 for Cu(II) and 2 μg L^?1 for Cd(II) in the studied medium. The good recoveries were obtained for the analysis in human plasma. The method was applied to blood samples, using the method of standard additions and the results were compared with Inductively Coupled Plasma‐Atomic Emission Spectrometry (ICP‐AES) as reference method. Furthermore, a simple digestion protocol of samples is investigated compared to the conventional digestion method.     

Bis(2, 2, 2-trichloroethoxy)cobalt(II) and chloro(2, 2, 2-trichloroethoxy) cobalt(II): synthesis and coordination chemistry

Summary Bis(2, 2, 2-trichloroethoxy) cobalt(II) and chloro(2, 2, 2-trichloroethoxy)cobalt(II) [Co(OCH₂CCl₃)₂·L] and [CoCl(OCH₂CCl₃)·L], derivatives (L=tetrahydrofuran, dioxan, triphenylarsine oxide, or pyridine) have been synthesised and characterized. They have tetrahedral geometry both in solution and in the solid state.