Flow Injection Chemiluminescence Determination of Isoniazid Using On-Line Electrogenerated Manganese(III) as Oxidant

A novel flow injection chemiluminescence (CL) system for the determination of isoniazid has been proposed. It is based on the direct CL reaction of isoniazid and Mn(III) in sulfuric acid medium. The unstable Mn(III) was on-line electrogenerated by constant current electrolysis. The CL emission intensity was linear with isoniazid concentration in the range 0.1–10 μg/mL; the detection limit was 3.2 × 10⁻² μg/mL. The whole process could be completed in 1 min with a relative standard deviation of less than 5%. The proposed method is suitable for automatic and continuous analysis and has been applied successfully to the analysis of isoniazid in pharmaceutical preparation.     

Flow Injection Chemiluminescence Determination of Pipemidic Acid Using On-Line Electrogenerated Cobalt(III) as Oxidant

 A novel flow injection chemiluminescence (CL) system for the determinati on of pipemidic acid is described. It is based on the direct CL reaction of pipemidic acid and Co(III) in acid medium. The unstable Co(III) was on-line electrogenerated by constant current electrolysis. The CL intensity was linear with pipemidic acid concentration in the range of 0.01∼100 μg/ml, the determination limit was 3.3×10⁻⁹ g/mL. The whole process could be complete d in 1 min with a relative standard deviation of 3.2%. The proposed method is suitable for automatic and continuous analysis and has been applied successfully to the analysis of pipemidic acid in a pharmaceutical preparation. Received November 22, 1999. Revision March 24, 2000.     

家兔血液中西咪替丁的微透析-毛细管电泳测定研究

本文报道用微透析毛细管电泳测定家兔血液中的西咪替丁。研究发现,采用如下条件:100mmol/LpH2.5的磷酸盐缓冲液,分离电压17kV,电动进样9kV×9s,西咪替丁与雷尼替丁能达到基线分离,据此以雷尼替丁为内标建立了一种测定西咪替丁的方法。西咪替丁与雷尼替丁峰面积比与相应的西咪替丁浓度在8.0×10-9～4.0×10-7g/mL范围内呈线性关系(r=0.998),检出限为5.0×10-9g/mL。药物代谢动力学参数由“NDST21”计算软件求得,代谢符合一室开放模型。     

Flow Injection Chemiluminescence Determination of Gentamycin Using On-Line Electrogenerated Co(III) As the Oxidant

ABSTRACT

A novel flow-injection Chemiluminescence (CL) system for the determination of gentamycin is described, based on the direct chemiluminescence reaction of gentamycin and Co(III) in sulfuric acid media. The unstable strongly oxidative Co(III) was electrogenerated on-line with constant current electrolysis. The chemiluminescence intensity was linear with gentamycin concentrations of 0.01～80μg/ml, the detection limit being 0.005μg/ml. The whole process could be completed in 1 min with a relative standard deviation of less than 3.2%. The proposed method is rapid and simple and is suitable for automatic and continuous analysis. This method has been applied satisfactorily to the analysis of gentamycin in pharmaceutical preparations.     

Microdialysis sampling and chemiluminescence detection for in vivo and real-time study of the lead metabolism in rabbit blood

The chemiluminescence (CL) system K₂MnO₄-luminol is shown to be useful for the determination of lead(II). The method is based on the catalytic effect of Pb(II) on the CL reaction. The linear range was 3 × 10⁻³–9 × 10⁻¹ mg L⁻¹ (r = 0.9971) and the relative standard deviation (R.S.D.) for 5 × 10⁻² mg L⁻¹ Pb(II) measurement was 0.7% (n = 11). The detection limit was 3 × 10⁻⁴ mg L⁻¹ (3σ) Pb(II). Based on this, an in vivo, on-line, real-time analytical system for monitoring the metabolism of free lead(II) in rabbit blood was developed. A microdialysis probe, implanted in the vein of a rabbit, was perfused with perfusate at a flow rate of 5 μL min⁻¹. The concentration of free lead(II) in the dialysate was determined on-line with a flow-injection CL system. This system included microdialysis sampling, on-line separation and chemiluminescence detection. The concentration-time curve of lead(II) was in accordance with the one-compartmental open model, T_1/2 (elimination half-life), T_max (peak time) and C_max (peak concentration) were 37.77 min, 85.20 min and 0.137 mg L⁻¹, respectively.     

Spectrophotometric Determination of Trace Chromium(VI) in Mass Chromium(III)

There is little conclusive evidence of the toxic effects of Cr(III) so far, but Cr(VI) has carcinogenic activity, so the analysis of the chromine ions is very important in environmental research and the quality control of industry products. Usually Cr(III) and Cr(VI) interfere with each other in the species analysis, the measurement of Cr(VI) of numerous previous papers is related to the Cr(VI) samples, which contain a little Cr(III). When the amount of trivalent chromine exceeds ten …     

Speciation of Cr(III) and Cr(VI) by Means of Melamine-Urea-Formaldehyde Resin and FAAS

 A method is described for the quantitative preconcentration and separation of trace chromium in water by adsorption on melamine-urea-formaldehyde resin. Cr(VI) is enriched from aqueous solutions on the resin. After elution the Cr(VI) is determined by FAAS. The capacity of the resin is maximal at ∼ pH 2. Total chromium can be determined by the method after oxidation of Cr(III) to Cr(VI) by hydrogen peroxide. The relative standard deviations (10 replicate analyses) for 10 mg/L levels of Cr(VI), Cr(III) and total chromium were 1.5, 3.5 and 2.8% respectively. The procedure has been applied to the determination and speciation of chromium in lake water, tap water and chromium-plating baths.     

可溶性锰(IV)化学发光反应的研究

发现了在甲醛存在的条件下, 可溶性锰(IV)与30余种有机物和无机物的化学发光反应. 以头孢菌素类药物(头孢曲松钠、头孢唑啉钠、头孢拉定和头孢哌酮钠)为分析对象优化了可溶性锰(IV)-甲醛-头孢菌素类药物化学发光反应的条件, 建立了测定四种头孢菌素类药物的流动注射化学发光新方法, 并将建立的方法用于药物制剂中头孢菌素类药物的含量测定．同时, 对化学发光反应的机理进行了初步探讨.     

Crystal Structure and Spin Frustration Behavior of an Oxo‐centered Trinuclear Chromium(III) Complex

A trinuclear chromium(III) complex, [Cr₃O(HCO₂)₆(CH₃OH)₃]NO₃·H₂O·CH₃OH ( 1 ), is synthesized and structurally characterized by single‐crystal X‐ray diffraction. Three chromium(III) ions are bridged by one oxygen atom in the center, forming a triangular structure. The HCOO ^? anion acts as bidentate ligand and bridges couples of Cr(III) ions. Magnetic susceptibility measurement indicates that a strong antiferromagnetic interaction is operative between chromium(III) ions, and the S = 1/2 ground state reveals normal spin frustration behavior.     

Mechanistic and Spectral Studies of the Ruthenium(III) Catalysed Oxidation of Sulfanilic Acid by Alkaline Hexacyanoferrate(III)

Summary. The kinetics of ruthenium(III) catalysed oxidation of sulfanilic acid (p-aminobenzenesulfonic acid) by hexacyanoferrate(III) in alkaline medium at a constant ionic strength of 2.5mol·dm^–3 has been studied spectrophotometrically using a rapid kinetic accessory. The reaction exhibits 2:8 stoichiometry (SNA:HCF(III)). The reaction showed first order kinetics in [hexacyanoferrate(III)] and [ruthenium(III)] and apparent less than unit order in both sulfanilic acid and alkali concentrations. The reaction rate increases with increasing ionic strength but the relative permittivity (_T) of the medium has a negligible effect on the rate of the reaction. Initial addition of reaction products did not affect the rate significantly. A mechanism involving the formation of a complex between sulfanilic acid and hydroxylated species of ruthenium(III) has been proposed. The active species of HCF(III) and ruthenium(III) are understood as [Fe(CN)₆^3–] and [Ru(H₂O)₅OH]²⁺, respectively. The main products were identified by IR, NMR, and mass spectral studies. The reaction constants involved in the different steps of mechanism are calculated. The activation parameters with respect to the slow step of the mechanism are computed and discussed and thermodynamic quantities are also calculated.     

Spectrophotometry Determination of Arsenic(III) and Antimony(III) by Means of Isonicotinoylhydrazones of 4-Dimethylaminobezaldehyde (4-Dbih) and 2-Hydroxynaphthaldehyde (2-Hnih)

Abstract

4-DBIH and 2-HNIH react with As(III) and Sb(III) respectively, in CH₃COOH medium to form colored complexes stable in presence of EDTA. As(III) and Sb(III) do not react with 2-HNIH and 4-DBIH respectively, and the Sb(III)-2-HNIH complex is extractable into isoamyl alcohol. These behaviours were used for the spectrophotometry determination of As (III) and Sb(III) in presence of several cations.     

Composition, Structure, and Corrosion–Electrochemical Properties of Chromium Coatings Deposited from Chromium(III) Electrolytes Containing Formic Acid and Its Derivatives

To study electrocatalytic properties of chromium, its deposits are obtained from Cr(III) electrolytes containing formic acid and its four derivatives (formaldehyde, methyl alcohol, formamide, dimethylformamide) and comprehensively examined. Amorphous structure of the deposits is established with an x-ray diffraction analysis. The valence state of chromium and major extrinsic elements is studied by x-ray photoelectron spectroscopy. The carbon reduction degree and the organization of carbon particles in deep layers of the deposits (chainlike or graphite-like structures) is shown to depend on the nature of organic compounds added into the chromium-plating electrolyte. The corrosion–electrochemical behavior of the obtained deposits in 0.5 M H₂SO₄ is compared to that of polycrystalline chromium and deposits plated from sulfate–oxalate Cr(III) electrolytes.     

Kinetic Studies on the Complexation of Chromium(III) with some Amino Acids in Aqueous Acidic Medium

Summary.  The kinetics of the formation of the 1:3 complex of chromium(III) with L-glutamic acid and DL-lysine were studied spectrophotometrically at and 550 nm. The reaction was found to be first order in both reactants. Increasing the hydrogen ion concentration from 3.2×10⁻⁵ to 1.0×10⁻³ molċdm⁻³ retarded the reaction rate which is of the form . Values of 28.8 and 63.6 kJċmol⁻¹ were obtained for the energy of activation and −184 and −116 Jċ K⁻¹ċmol⁻¹ for the entropy of activation for L-glutamic acid and DL-lysine. The logarithms of the formation constants of the two complexes were found to be 5.9 and 5.1. Received January 7, 2000. Accepted (revised) March 8, 2000     

Thermal decomposition of chromium(III) nitrate(V) nanohydrate

Thermal decomposition of Cr(NO₃)₃·9H₂O in helium and in synthetic air was studied by means of TG, DTA, EGA and XRD analysis. The dehydration occurs together with decomposition of nitrate(V) groups. Eight distinct stages of reaction were found. Intermediate products of decomposition are hydroxy- and oxynitrates containing chromium in hexa- and trivalent states. The process carried out in helium leads to at about 260°C and in air is formed at about 200°C. The final product of decomposition (>450°C) is Cr₂O₃, both in helium and in air. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Novel Enhancing Flow-Injection Chemiluminescence Method for the Determination of Glutathione Using the Reaction of Luminol with Hydrogen Peroxide

 A rapid flow-injection method with chemiluminescence (CL) detection is described for the determination of glutathione (GSH). The method is based on the CL reaction of luminol and hydrogen peroxide. GSH can greatly enhance the chemiluminescence intensity in 0.1 mol/L borax–sodium hydroxide buffer solution (pH = 9.7). The maximum CL intensity was directly proportional to the concentration of GSH in the range 3.0 × 10⁻⁷–2.0 × 10⁻⁵ mol/L, and the detection limit was 6.8 × 10⁻⁸ mol/L. The relative standard deviation was 3.4% for 5.0 × 10⁻⁶ mol/L of GSH (n = 11). Received October 23, 2001; accepted June 18, 2002     

Biphasic oxidation of diaquadichloro(1,10-phenanthroline)chromium(III) by N-bromosuccinimide and the formation of chromium(IV) and chromium(V)

The kinetics of oxidation of diaquadichloro(1,10-phenanthroline)chromium(III) complex, [Cr^III(phen)(H₂O)₂Cl₂]⁺, by N-bromosuccinimide (NBS) is biphasic. The first faster step involves the oxidation of Cr(III) to Cr(IV). The second slower step is due to the oxidation of Cr(IV) to Cr(V). The reaction product is isolated and characterized by electron spin resonance (ESR), IR, and elemental analysis. The chromium(V) product is consistent with the formula [Cr^V(phen)Cl₂(O)]Br. The rate constants k_f and k_s, for the faster and the slower steps respectively, were obtained using an Origin 9.0 software program. Values of both k_f and k_s, varied linearly with [NBS] at constant reaction conditions. The effect of pH on the reaction rate is investigated over the pH (4.11–6.01) range at 25.0°C. The rate constants k_f and k_s increased with increasing pH. This is consistent with hydroxo forms of the chromium species being more reactive than the aqua forms. Chromium(III) complexes, more often than not, are inert. The oxidation of the Cr(III) complex to Cr(IV), most likely, proceeds by an outer sphere mechanism. Since chromium(IV) is labile the mechanism of its oxidation to chromium(V) is not certain.     

Study on Speciation of Pr(III) in Human Blood Plasma by Computer Simulation

Biological effects of metal are controlled by its in vivo speciation l'2. It is not possible todetermine in vivo speciation of metals with analytical methods so far. The lowmolecular-weight complex distribution of biometal ions in blood plasma was studied bycomputer simulation'. Soluble species of rare earth were also reported 2'3. However,insoluble species of rare earth in blood plasma have not been studied, it is the aim of thispaper to study insoluble species by computer simulation.We impr…     

The Study on the Stability Constant and Species Distribution of Eu (III) and Tb (III) Complexes with BDBPH

Biomimetic hydrolysis of DNA or RNA is of increasing importance in biotechnology and medicine. The ability to cleave nucleic acids efficiently, in a non-degradative manner, and with high levels of selectivity for site or structure will be required by many applications for the manipulation of genes, the design of structural probes and the development of novel therapeutics1. There has been much interest in the development of lanthanide complexes as nucleic acid cleavage agents. It has been fou…