Assay of femtogram level nitrite in human urine using luminol–myoglobin chemiluminescence

In this paper, a sensitive flow injection chemiluminescence system luminol–myoglobin was described for determining femtogram nitrite. Nitrite bound myoglobin producing the ferric heme nitrite complexes, which catalyzed the electron transfer of luminol to myoglobin leading to fast chemiluminescence. The chemiluminescence intensity in the presence of nitrite was remarkably enhanced compared with that in the absence of it. Under the optimum reaction conditions the chemiluminescence increment produced was proportional to the concentration of nitrite in the range of 0.05 pg ml^− 1–1.0 ng ml^− 1 (R² = 0.9991), with a detection limit (3σ) of 20.0 fg ml^− 1. At the flow rate of 2.0 ml min^− 1, the whole process including sampling and washing could be completed in 0.5 min offering the sampling efficiency of 120 h^− 1 accordingly, and the relative standard deviation (RSD) was less than 2.60% (n = 5). It was satisfactory for the application to determine nitrite in human urine samples, and the possible mechanism was proposed.     

Photometrische Bestimmung kleinster CN?- und SCN?-Grehalte in Abw?ssern der Erd?lverarbeitung

Zusammenfassung Die photometrische Bestimmung kleinster CN^–- und SCN^–-Gehalte nach dem Benzidin-Pyridin-Verfahren wird beschrieben, wobei hauptsÄchlich der Einflu\ eines gro\en Sulfidüberschusses nÄher untersucht wird. Für eine einwandfreie Bestimmung ist die Kenntnis des genauen S^2–-Gehaltes erforderlich, da sich danach die zur Oxydation des Sulfidschwefels sowie zur Einhaltung eines konstanten Bromüberschusses erforderliche Brommenge richtet. Um diese besser dosieren zu können, wird eine KBr₃-Lösung mit bekanntem Bromgehalt angewandt. Farbentwicklung und Absorption werden untersucht und das Absorptionsmaximum bei 520 m festgestellt.Die Analyse ist anwendbar für CN^–- und SCN^–-haltige AbwÄsser auch mit höheren Ammonium- und Alkalisulfidgehalten sowie für starke Waschlaugen und CN^–-haltige Gase.     

Interaction of iron carbonyls with Lewis bases

The interaction of iron carbonyls Fe _n (CO) _m (wheren = 1,m = 5;n = 2,m = 9;n = 3,m = 12) with anionic Lewis bases (H^–, F^–, Cl^–, Br^– , I^–, CN^–, SCN^–, N₃ ^–, MeSO₃ ^–, MeCO₂ ^–, CF₃CO₂ ^–, S₂ ^–, CO₃ ^2–, and SO₄ ^2–) passes through two-stage redox-disproportionation. The first stage is the formation of an iron carbonyl-base complex, [Fe _n (CO) _m–1C(O)L]^–, and the second is a single-electron reduction of this complex by another molecule of the initial iron carbonyl, giving rise to Fe(l) and Fe(–l) derivatives.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 248–249, January, 1996.     

Detection of peroxyacetyl nitrate in air using chemiluminescence aerosol detector

A method for the rapid and sensitive determination of peroxyacetyl nitrate (PAN) in air based on a chemiluminescence reaction with an alkaline solution of luminol in the chemiluminescence aerosol detector is described. The PAN is chromatographically separated from nitrogen dioxide and ozone in a packed column filled with 5 % OV-1 on Chromosorb 30/60 and the eluted PAN is detected via the direct reaction with the luminol solution consisting of 0.002 mol L^?1 luminol, 1 vol. % Brij-35 and 0.1 mol L^?1 KOH. The limit of detection is 14.9 ng m^?3 (3 ppt) of PAN. Alternatively, the PAN after separation is thermally converted to NO₂ which is detected by the chemiluminescence reaction with a solution consisting of 0.002 mol L^?1 luminol, 0.5 mol L^?1 KOH, 0.2 mol L^?1 Na₂SO₃, 0.1 mol L^?1 KI, 0.05 mol L^?1 EDTA and 0.5 vol. % triton X-100. The alternative approach affords the simultaneous determination of PAN and NO₂. The limit of detection is 50 ppt of PAN and 50 ppt of NO₂. The time resolution is 3 min. The method was applied to the measurement of ambient peroxyacetyl nitrate in air.     

Direkt-potentiometrische Konzentrationsbestimmungen mit ionensensitiven Elektroden unter Verwendung komplexierender Hilfsreaktionen

Zusammenfassung Die Grundlagen der direkt-potentiometrischen Konzentrationsbestimmung von Anionen und Kationen werden beschrieben, für die keine ionensensitiven Elektroden bekannt sind. Es wird die Konzentrationsabnahme eines Hilfsions gemessen, das mit dem analytisch zu bestimmenden Ion einen stabilen Komplex bildet.Ausführliche Angaben werden zur Bestimmung von Al³⁺ mit F^– als Hilfsion und von Ni²⁺ mit CN^– als Hilfsion gemacht. Auf die prinzipiellen Möglichkeiten einer Bestimmung von Fe²⁺, Fe³⁺, Au⁺, Hg²⁺, Th⁴⁺, Zr⁴⁺, UO₂ ²⁺, SCN^– und S₂O₃ ^2– wird eingegangen.

---

Direct-potentiometric determinations with ion-sensitive electrodes using complexing auxiliary reactions

The basic principles of the direct-potentiometric determination of several cations and anions are discussed, for which no ion-sensitive electrode is available. The decrease in concentration of an auxiliary ion is measured which forms stable complexes with the ion to be determined. Detailed information is given on the determination of Al³⁺ with F^– as auxiliary ion and of Ni²⁺ with CN^– as auxiliary ion. An outlook is presented on the possible determinations of Fe²⁺, Fe³⁺, Au⁺, Hg²⁺, Th⁴⁺, Zr⁴⁺, UO₂ ²⁺, SCN^– and S₂O₃ ^2–.

     

Bond functions and the topological properties of the bonds

The effect of bond functions on the topological properties of the bonds is studied by performing Hartree-Fock calculations for O₂, Cl₂, F₂, CN^–, N₂ and LiCl molecules. The results show that bond functions increse the degree of covalency of the bonds and the electronic density at the (3, –1) bond critical point. This effect is quite noticeable for intermediate interactions molecules (F₂ and CN^–) where a is obtained instead of a positive value. The optimal position of the bond functions seems to be at or near the (3, –1) bond critical point.     

A flow-injection ultrafiltration sampling chemiluminescence system for on-line determination of drug–protein interaction

A flow-injection ultrafiltration sampling chemiluminescence system for on-line determination of cimetidine–bovine serum albumin (BSA) interaction is proposed in this paper. Cimetidine can be oxidized by N-bromosuccinimide (NBS) and sensitized by fluorescein to produce high chemiluminescence emission in basic media. The concentration of cimetidine is linear with the CL intensity in the range 3×10^–7–1×10^–4 mol L^–1 with a detection limit of 1×10^–7 mol L^–1 (3). The drug and protein were mixed in different molar ratios in 0.067 mol L^–1 phosphate buffer, pH 7.4, and incubated at 37 °C in a water bath. The ultrafiltration probe was utilized to sample the mixed solution at a flow rate of 5 µL min^–1. The data obtained by the proposed ultrafiltration flow-injection chemiluminescence method was analyzed with Scrathard analysis and a Klotz plot. The estimated association constant (K) and the number of the binding site (n) on one molecule of BSA by Scrathard analysis and Klotz plot were 3.15×10⁴ L mol^–1 and 0.95, 3.25×10⁴ L mol^–1 and 0.92, respectively. The proposed system proved that flow-injection chemiluminescence analysis coupled with on-line ultrafiltration sampling is a simple and reliable technique for the study of drug–protein interaction.     

Inversvoltammetrische Untersuchung von Cyanidspuren am h?ngenden Quecksilbertropfen

Zusammenfassung Cyanidspuren lassen sich in Gegenwart von Kupfer(II)-ionen mit Hilfe der inversen Voltammetrie am hängenden Hg-Tropfen unter Anreicherung quantitativ bestimmen. Wahrscheinlich beruht diese Möglichkeit auf der Bildung von unlöslichem CuCN auf der Elektrodenoberfläche. Man kann entweder die Abnahme des Cu-Peaks oder die Bildung des Oxydationspeaks bei + 0,17 V den Bestimmungen zugrunde legen. Untersuchungen über den Einfluß von SCN^–, Cl^–, Br^{– –} und J^– ergaben, daß die CN^–-Bestimmung unter bestimmten Konzentrationsverhältnissen möglich ist.

---

Summary Traces of cyanide can be quantitatively determined by inverse voltammetry in the presence of copper(II) ions after accumulation at the hanging mercury drop. Probably the determination is due to the formation of insoluble CuCN at the surface of the electrode. It is possible to determine the decrease of the copper peak or the formation of the second oxidation peak at +0.17 V. The investigation of the influence of SCN^–, Cl^–, Br^– and J^– showed that the determination of CN^– is possible in the presence of certain proportions of concentrations of these ions.

     

Infrared spectral studies of ion association in nonaqueous solutions of cyanide salts with consequences for their nucleophilic reactivity

An infrared spectrometric study of alkali metal and tetraphenylarsonium cyanide (As ⁴ CN) solutions in DMSO or DMF shows that even for concentrations of 0.1M a large proportion of the ions are associated. The order of basicity established through methanol (OH) frequency shifts is CN^–>Cl^–>Br^–. Addition of common ions or cyclic polyether to these solutions, as well as correlations between the (CN^–) frequencies and those of the (CN) bands of CH₃CN bonded to the same cations, suggests assignments of the observed bands to solvated contact ion pairs M⁺ CN^–, triple ions M⁺ CN^– M⁺, and aggregates (M⁺ CN) _n ^– . The nucleophilic reactivity of these salts is related to the structure of these solutions.This article is taken in part from the thesis of A. Loupy, University Paris-Sud Orsay, April 9, 1975, CNRS thesis order No. AO 10102.     

Enhancing effect of DNA on chemiluminescence from the decomposition of hydrogen peroxide catalyzed by copper(II)

In the absence of any special luminescence reagent, emission of weak chemiluminescence has been observed during the decomposition of hydrogen peroxide catalyzed by copper(II) in basic aqueous solution. The intensity of the chemiluminescence was greatly enhanced by addition of DNA and was strongly dependent on DNA concentration. Based on these phenomena, a flow-injection chemiluminescence method was established for determination of DNA. The chemiluminescence intensity was linear with DNA concentration in the range 2×10^–7–1×10^–5 g L^–1 and the detection limit was 4.1×10^–8 g L^–1 (S/N=3). The relative standard deviation was less than 3.0% for 4×10^–7 g L^–1 DNA (n=11). The proposed method was satisfactorily applied for determination of DNA in synthetic samples. The possible mechanism of the CL reaction is discussed.     

Flow injection chemiluminescence determination of l-cysteine in amino acid mixture and human urine with the BrO3 −–quinine system

In this paper, a novel flow injection chemiluminescence (CL) determination of l-cysteine is proposed. The method is based on the CL reaction of l-cysteine and KBrO₃ in acidic medium. The CL intensity was greatly enhanced in the presence of quinine. The CL intensity was linear with l-cysteine concentration in the range of 0.2–80 g L^–1, and the detection limit was 0.1 g L^–1 (3). A complete analysis, including sampling and injecting, could be performed in 1 min, giving a throughput of about 60 h^–1. The relative standard deviation was 1.6% for 0.8 g L^–1 l-cysteine (n=11). The proposed method was satisfactorily applied to the determination of cysteine in an amino acid mixture and human urine. The mechanism of the CL reaction is also discussed.     

Electrochemical analysis of the coordination sphere of ruthenium(ii) as electron transfer mediator in glucose oxidase catalysis in aqueous solutions

The redox potentials of the cis-[Ru(LL)₂XY]ⁿ⁺ complexes (LL = 2,2"-bipyridyl (bpy), 1,10-phenanthroline (phen), and 4,4"-dimethyl-2,2"-bipyridyl (Me₂bpy); X, Y = Cl^–, Br^–, CO₃ ^2–, NO₂ ^–, SCN^–, N₃ ^–, H₂O, and DMSO) in aqueous buffer solutions were measured and analyzed in the framework of the Lever theory on the additivity of contributions of ligands (E _L) to the apparent redox potential of the complex (E ^o"). The complexes manifest the properties of reversible or quasireversible redox systems, whose formal redox potentials lie in the 0.2—0.5 V range. The complexes are efficient electron transfer mediators between the active center of glucose oxidase (GO) from Aspergillus niger and an electrode.     

Porphyrins

The extended Hückel model is further developed to allow prediction of spin state and is applied to ferrous porphin complexes with H₂O, CO, O₂, N₂ and ferric porphin complexes with OH^–, F^–, Cl^–, CN^–. The model shows that if the iron atom lies in the porphyrin plane only low or intermediate spin states are possible, with the weakest ligands just producing low spin. The high spin (ionic) complex can only occur with iron displaced from the plane, in which geometry CO and CN^– are calculated to be low spin, OH^–, F^–, Cl^– high spin, and H₂O borderline between low and high. The model predicts that N₂ will not bond and that a stable O₂ complex is impossible if O₂ is perpendicular to the plane. Discussion is given of the ligand field, absorption spectra, soft X-ray spectra, and Mössbauer spectra.

---

Zusammenfassung Das erweiterte Hückelmodell wird in einer Weise ausgebaut, daß Aussagen über Spinzustände möglich werden. Das Verfahren wird auf eisen-(II)-haltige Porphyrinkomplexe mit H₂O, CO, O₂ und N₂ als Liganden und eisen-(III)-haltige Komplexe mit OH^–, F^–, Cl^– und CN^– angewendet. Dabei zeigt sich, daß nur Zustände mit niedrigem oder mittlerem Spin möglich sind, wenn das Eisenatom in der Porphyrin-Ebene liegt, und daß dabei die schwächsten Liganden den niedrigsten Spin ergeben. Komplexe mit hohem Spin (Ionenkomplexe) sind nur dann möglich, wenn das Eisen nicht in der Ebene liegt, und zwar haben dann der CO- und der CN^–-Komplex niedrigen, der OH^–-, F^–- und Cl^–-Komplex hohen und der H₂O-Komplex entweder hohen oder niedrigen Spin. Das Modell ergibt ferner, daß N₂ nicht gebunden wird und daß ein stabiler O₂-Komplex nur entsteht, wenn das O₂-Molekül senkrecht zur Bindungsebene steht. Zum Schluß werden Ligandenfeld, Absorptionsspektren, weiche Röntgenspektren und Mössbauerspektren diskutiert.

---

Résumé Le modèle de Hückel étendu est élaboré de manière á permettre la prédiction de l'état de spin et est appliqué aux complexes de la porphine ferreuse avec H₂O, CO, O₂, N₂ et de la porphine ferrique avec OH^–, F^–, Cl^–, CN^–. Ce modèle montre que, si l'atome de fer se trouve dans le plan de la porphyrine, seuls des états de spin bas et intermédiaires sont possibles, les ligands les plus faibles donnant seulement un spin bas. Le complexe à spin élevé (ionique) ne peut exister qu'avec le fer en dehors du plan, auquel cas on calcule un spin bas pour CO et CN^–, haut pour OH^–, F^–, Cl^–, et l'un ou l'autre pour H₂O. Ce modèle permet de prédire que N₂ ne se liera pas et qu'un complexe stable avec O₂ est impossible si O₂ est perpendiculaire au plan. On discute le champ des ligands, le spectre d'absorption, le spectre des rayons X mous et le spectre Mössbauer.

---

---

National Institutes of Health Pre-Doctoral Fellow.     

Equilibrium constants of some protonated,nonprotonated and hydroxo complexes of uranium(VI) with xylenol orange

Summary The species, UO₂H₃L^–, UO₂H₂L^2–, UO₂HL^3–, UO₂L^4–, UO₂(OH)L^5– and UO₂(OH)₂L^6– are found in the equilibria between uranyl ions and 3,3-bis[N,N-di(carboxymethyl)-aminomethyl]-o-cresolsulphonphthalein (H₆L; xylenol orange; dcac) in aqueous solution. The equilibria have been studied by the potentiometric method at 25° and at an ionic strength of 0.1M (KNO₃). New algebraic equations have been employed to evaluate the equilibrium constants.     

A Highly Sensitive and Selective Assay for Cysteine Using the Chemiluminescence Reaction of Luminol and Hydrogen Peroxide

A very simple, highly sensitive and selective chemiluminescence (CL) method was established for the determination of cysteine. This method is based on the fact that the CL reaction of luminol and hydrogen peroxide can be greatly enhanced by cysteine. The CL intensities at maximum light emission were linearly correlated with the concentration of cysteine over the range of 2.0×10^–8–6.0×10^–6molL^–1 with a detection limit of 7.5×10^–9molL^–1. The relative standard deviation was 1.7% for the determination of 1.0×10^–7molL^–1 cysteine (n=9). The feasibility of utilizing the proposed method for the determination of total concentration of cysteine in human serum was examined.     

Determination of dopamine in synthetic cerebrospinal fluid by SWV with a graphite–polyurethane composite electrode

This work describes an electroanalytical investigation of dopamine using cyclic voltammetry (CV) and the graphite–polyurethane composite electrode (GPU). In CV studies, well-defined redox peaks characterize the oxidation process at the GPU electrode, which is indicative of electrocatalytic effects associated with active sites on the GPU electrode surface. A new analytical methodology was developed using the GPU electrode and square wave voltammetry (SWV) in BR buffer solution (0.1 mol L^–1; pH 7.4). Analytical curves were constructed under optimized conditions (f=60s^–1, E_a=50 mV, E_I=2 mV) and detection and quantification limits of 6.4×10^–8 mol L^–1 (12.1 g L^–1) and 5.2×10^–6 mol L^–1 (0.9 mg L^–1), respectively, were achieved. The precision of the method was checked by performing ten successive measurements for a 9.9×10^–6 mol L^–1 dopamine solution. For intra-assay and inter-assay precisions, the relative standard deviations were 1.9 and 2.3%, respectively. In order to evaluate the developed methodology, the determination of dopamine was performed with good sensitivity and selectivity, without the interference of ascorbic acid in synthetic cerebrospinal fluid, which indicates that the new methodology enables reliable analysis of dopamine.     

Activity of Aliphatic Diperoxy Acids in the Luminol Chemiluminescence Reaction

The activity of dilute aqueous solutions of aliphatic diperoxysuccinic, -glutaric, -adipic, and -sebacic acids in the luminol chemiluminescence reaction is studied. This activity can be detected at a low (10^–6–10^–5M) concentration of luminol in weakly alkaline solutions; it increases as the alkyl chain length of the acid decreases. The best conditions for chemiluminescence have been selected. It has been shown that individual or total diperoxy acids can be determined by luminol chemiluminescence. The determination limit for diperoxyadipic acid used as an example has been estimated at 2.0 ng/mL.     

Quantitative chemical analysis on paper. I

Summary A method has been proposed for the determination of small quantities of Cl^–, SCN^– and I^– in mixtures. The method is based on the use of filter paper evenly impregnated with Ag₂CrO₄. The method permits the determination of 5 to 50g of Cl^–; 15 to 100g of I^– and 10 to 150g of SCN^– with an accuracy of 1.5%.The method may also be used for determination of SCN^– alone.

---

Zusammenfassung Ein Verfahren für die Bestimmung kleiner Mengen Chlorid, Rhodanid und Jodid in deren Gemischen wird vorgeschlagen. Es beruht auf der Verwendung eines mit Silberchromat gleichmäßig imprägnierten Filtrierpapierstreifens und ermöglicht die Bestimmung von 5 bis 50g Chlorid,15 bis 100g Jodid und 10 bis 150g Rhodanid mit einer Genauigkeit von 1,5%. Das Verfahren kann auch für die Bestimmung von Rhodanid allein verwendet werden.

---

Résumé On a proposé une méthode pour le dosage de petites quantités de Cl^–, SCN^–, et I^– en mélanges. La méthode est fondée sur l'emploi d'un papierfiltre uniformément imprégné d'Ag₂CrO₄. Elle permet le dosage de 5 à 50g de Cl^–, 15 à 100g d'I^– et de 10 à 150g de SON^–, à la précision de 1,5%. On peut aussi utiliser la méthode pour le dosage de SCN^– seul.

     

Conditions for the synthesis of Sb(III) fluoride complexes

Complexation of Sb(III) fluorides with alkali metal, ammonium, and thallium cations in the MF-SbF₃-H₂O systems at the molar ratios MF : SbF₃=(0.01–2) : 1 is studied by preparative chemistry, pH-metry, ₁₉F NMR, IR and X-ray powder diffraction methods. The crystals of Sb₃O₂F₅, MSb₄F₁₃, MSb₃F₁₀, MSb₂F₇, M₂Sb₃F₁₁, M₃Sb₄F₁₅, MSbF₄, M₂SbF₅ are synthesized and the factors influencing their formation are discussed. Some types of Sb(III) fluoride complexes are shown to be formed in the MX-SbF₃-H₂O systems (X = Cl^–, NO₃^–, BF₄^–, SCN^–, ClO₄^–).Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 833–837.Original Russian Text Copyright © 2004 by Zemnukhova, Kovaleva, Fedorishcheva, Konshin, Davidovich.