Presence Of Cyanide Ion Research Articles

Cyclic voltammetric study of the oxifddation of quinizarin in the presence of cyanide ion

Cyclic voltammetric study of the oxifddation of quinizarin in the presence of cyanide ion

Contribution of Artifacts toN-Methylated Piperazine Cyanide Adduct Formation In Vitro fromN-Alkyl Piperazine Analogs

In the liver microsome cyanide (CN)-trapping assays, piperazine-containing compounds formed significant N-methyl piperazine CN adducts. Two pathways for the N-methyl piperazine CN adduct formation were proposed: 1) The α-carbon in the N-methyl piperazine is oxidized to form a reactive iminium ion that can react with cyanide ion; 2) N-dealkylation occurs followed by condensation with formaldehyde and dehydration to produce N-methylenepiperazine iminium ion, which then reacts with cyanide ion to form the N-methyl CN adduct. The CN adduct from the second pathway was believed to be an artifact or metabonate. In the present study, a group of 4'-N-alkyl piperazines and 4'-N-[¹³C]methyl-labeled piperazines were used to determine which pathway was predominant. Following microsomal incubations in the presence of cyanide ions, a significant percentage of 4'-N-[¹³C]methyl group in the CN adduct was replaced by an unlabeled natural methyl group, suggesting that the second pathway was predominant. For 4'-N-alkyl piperazine, the level of 4'-N-methyl piperazine CN adduct formation was limited by the extent of prior 4'-N-dealkylation. In a separate study, when 4'-NH-piperaziens were incubated with potassium cyanide and [¹³C]-labeled formaldehyde, 4'-N-[¹³C]methyl piperazine CN-adduct was formed without NADPH or liver microsome suggesting a direct Mannich reaction is involved. However, when [¹³C]-labeled methanol or potassium carbonate was used as the one-carbon donor, 4'-N-[¹³C]methyl piperazine CN adduct was not detected without liver microsome or NADPH present. The biologic and toxicological implications of bioactivation via the second pathway necessitate further investigation because these one-carbon donors for the formation of reactive iminium ions could be endogenous and readily available in vivo.

Enhancing Fluorescence LC Analysis of Biogenic Amines in Fish Tissues by Precolumn Derivatization with Naphthalene-2,3-dicarboxaldehyde

This work reports a sensitive high-pressure liquid chromatography method for the simultaneous determination of biogenic mono- and diamines in fish tissues. Highly fluorescent derivatives of the amines were obtained by precolumn derivatization with naphthalene-2,3-dicarboxaldehyde, in the presence of cyanide ion as the nucleophile and of heptylamine as the internal standard. The chromatographic separation was performed using a mobile phase of acetonitrile/methanol/10 % (v/v) acetone in water, delivered in gradient mode on an Inertsil ODS-3 column (250 × 4 mm i.d., 5 μm). The method was successfully applied to the analysis of fresh and canned tuna fish tissues, subjected to ultrasound-assisted liquid–liquid extraction. The variables affecting the derivatization yield as well as the extraction recovery of the analytes from the sample matrix were investigated. Results were quantified against the internal standard, according to the matrix-matched approach. Limits of detection between 2.5 and 330 mg kg−1 sample were achieved. The precision and accuracy of assay in samples was satisfactory, yielding relative standard deviation and recovery values between 0.3 and 4.2 % and 81.0 and 102.5 %, respectively.

Study of the naphthalene-2,3-dicarboxaldehyde pre-column derivatization of biogenic mono- and diamines in mixture and fluorescence−HPLC determination

A new fluorescence-HPLC method was developed for the simultaneous determination of eight biogenic monoamines (histamine, methylamine, tyramine, ethylamine, propylamine, tryptamine, 2-phenylethylamine, isoamylamine) and two biogenic diamines (putrescine, cadaverine) in the presence of heptylamine as the internal standard. The amines were pre-column derivatized with naphthalene-2,3-dicarboxaldehyde in the presence of cyanide ion as the nucleophile. The effect of the derivatization reaction conditions on the reaction yield was investigated. The derivatives were separated on an Inertsil ODS-3 column (250 × 4mm i.d., 5 μm) using gradient elution and detected fluorimetrically at excitation and emission wavelengths of 424 and 494 nm, respectively. Limits of detection between 0.002 and 0.4 ng, injected on-column (10-μL loop), were achieved. The within- and between-day relative standard deviations ranged between 0.2-3.4% and 0.3-4.8%, respectively. The utility of the method in assaying biogenic mono- and diamine mixtures in Greek cheeses is demonstrated. Ultrasound-assisted liquid-liquid extraction was applied prior to derivatization.

A Label‐Free Gold‐Nanoparticle‐Based SERS Assay for Direct Cyanide Detection at the Parts‐per‐Trillion Level

Cyanide is an extremely toxic lethal poison known to humankind. Developing rapid, highly sensitive, and selective detection of cyanide from water samples is extremely essential for human life safety. Driven by the need, here we report a gold-nanoparticle-based label-free surface-enhanced Raman spectroscopy (SERS) system for highly toxic cyanide ion recognition in parts-per-trillion level and to examine gold-nanoparticle-cyanide interaction. We have shown that the SERS assay can be used to probe the gold nanoparticle dissociation process in the presence of cyanide ions. Our experimental data indicates that gold-nanoparticle-based SERS can detect cyanide from a water sample at the 110 ppt level with excellent discrimination against other common anions and cations. The results also show that the SERS probe can be used to detect cyanide from environmental samples.

Voltammetric study of the oxidation of quercetin and catechin in the presence of cyanide ion

The reaction of electrochemically generated o-benzoquinones from oxidation of quercetin and catechin as Michael acceptors with cyanide ion as nucleophile has been studied using cyclic voltammetry. The reaction mechanism is believed to be EC; including oxidation of catechol moiety of these antioxidants followed by Michael addition of cyanide ion. The observed homogeneous rate constants (kobs) for reactions were estimated by comparing the experimental voltammetric responses with the digitally simulated results based on the proposed mechanism. The effects of pH and nucleophile concentration on voltammetric behavior and the rate constants of chemical reactions were also described.

Silver nanoparticles as a cyanide colorimetric sensor in aqueous media

The interaction between aqueous colloidal silver nanoparticles (AgNPs) and cyanide ions was studied using UV-Vis absorption and scanning electron microscopy (SEM) techniques. It was found that AgNPs were oxidized by dissolved oxygen in the presence of cyanide ions, resulting in a considerable decrease in the intensity of the surface plasmon resonance (SPR) absorption band of AgNPs. So, we propose a simple, cost effective, rapid, sensitive and selective colorimetric sensor for the detection of cyanide using AgNPs in aqueous media. There is a linear relationship between the absorbance intensity of AgNPs and the concentration of cyanide ions over the range of 16.7 μmol L−1–133.3 μmol L−1 at 394 nm. The proposed method has been successfully used for the determination of cyanide in water samples.

Reactions of nitrite with hemoglobin measured by membrane inlet mass spectrometry

Membrane inlet mass spectrometry was used to observe nitric oxide in the well-studied reaction of nitrite with hemoglobin. The membrane inlet was submerged in the reaction solutions and measured NO in solution via its flux across a semipermeable membrane leading to the mass spectrometer detecting the mass-to-charge ratio m/z 30. This method measures NO directly in solution and is an alternate approach compared with methods that purge solutions to measure NO. Addition to deoxy-Hb(Fe II) (near 38 µM heme concentration) of nitrite in a range of 80 µM to16 mM showed no accumulation of either NO or N 2O 3 on a physiologically relevant time scale with a sensitivity near 1 nM. The addition of nitrite to oxy-Hb(Fe II) and met-Hb(Fe III) did not accumulate free NO to appreciable extents. These observations show that for several minutes after mixing nitrite with hemoglogin, free NO does not accumulate to levels exceeding the equilibrium level of NO. The presence of cyanide ions did not alter the appearance of the data; however, the presence of 2 mM mercuric ions at the beginning of the experiment with deoxy-Hb(Fe II) shortened the initial phase of NO accumulation and increased the maximal level of free, unbound NO by about twofold. These experiments appear consistent with no role of met-Hb(Fe III) in the generation of NO and an increase in nitrite reductase activity caused by the presumed binding of mercuric to cysteine residues. These results raise questions about the ability of reduction of nitrite mediated by deoxy-Hb(Fe II) to play a role in vasodilation.

Spectrofluorimetric determination of tranexamic acid in hydrogel patch formulations by derivatization with naphthalene‐2, 3‐dicarboxaldehyde/cyanide

The aim of this research was to develop and validate a spectrofluorimetric method for determination of tranexamic acid in hydrogel patch formulations. Tranexamic acid (trans-4-aminomethylcyclohexanecarboxylic acid, trans-AMCHA) is an antifibrinolytic drug that recently gained attention as a skin-whitening agent due to its inhibitory effect on ultraviolet (UV)-induced pigmentation in vivo. Derivatization with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide ion (CN(-)) to produce a fluorescent 1-cyanobenz[f]isoindole (CBI) product (lambda(ex) = 420 nm, lambda(em) = 480 nm) is for the first time reported for the determination of tranexamic acid in hydrogel patch formulations. Other separation techniques were not used in the analysis of the CBI-fluorescent product as required in the previous studies. The developed method was proven to be precise and accurate with percent recoveries ranging between 98.0% and 101.8% at the concentration range of 8.4-84.0 microg/ml (R(2) > 0.999). The intra- and inter-day precisions as expressed by the relative standard deviations (RSD) were below 1.85%. Derivatization of tranexamic acid with NDA/CN(-) was completed within five minutes and was stable for at least 30 minutes. The method has been applied to the analysis of drug content and release profiles in tranexamic hydrogel patch formulations.

Kinetics of hydrogen evolution reaction on nanocrystalline electrodeposited Ni 62Fe 35C 3 cathode in alkaline solution by electrochemical impedance spectroscopy

Ternary nickel–iron–carbon (Ni–Fe–C) alloys have been characterized by means of microstructural and electrochemical techniques in view of their possible applications as electrocatalytic materials for hydrogen evolution reaction (HER). The electrochemical efficiency of the electrodes has been evaluated on the basis of electrochemical data obtained from the steady-state polarization Tafel curves, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in 1 M NaOH solution at 298 K in the absence and presence of cyanide ion as the poison. Steady-state polarization Tafel curves showed that the Ni–Fe–C electrodes were apparently active for the HER. Therefore, the EIS studies were performed to obtain more precise data and find the source of activity. A surface roughness of more than three orders of magnitude was observed for Ni 62Fe 35C 3 electrode. The rate constants of the forward and backward reactions of Volmer and Heyrovský steps were estimated by using Tafel-impedance data. A comparison between the values obtained for R f by the EIS and the values obtained for k 2 by approximation of Tafel-impedance data revealed that the increase in activity of Ni 62Fe 35C 3 electrode toward the HER was partially (20%) originated from increase in the surface roughness, and mostly (80%) from increase in the intrinsic activity.

An isocratic high performance liquid chromatography method for the determination of GABA and glutamate in discrete regions of the rodent brain

The amino acid neurotransmitters γ-aminobutyric acid (GABA) and glutamate have been implicated in mood disorders and high performance liquid chromatography (HPLC) is an important method in their quantitation. This paper describes a method which employs either electrochemical or fluorescent detection of the amino acid derivatives formed by a reaction with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide ions. Elution is based on an isocratic protocol and is achieved in 20min or less. The method is reproducible, shows excellent linearity and generates derivatives which are stable for up to 16h. Successful application of the method to a maternal deprivation study has identified the hippocampus and the brainstem as possible sites of long-term alteration in this paradigm.

Reaction of Naphthalene‐2,3‐dicarbaldehyde with Cyanide; a Unique Oxidative Condensation Product.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Reaction of naphthalene-2,3-dicarbaldehyde with cyanide; A unique oxidative condensation product

Naphthalene-2,3-dicarbaldehyde (NDA), a reagent used for the fluorescent detection of amino acids in the presence of cyanide, self-condenses in the presence of cyanide ion and methanol at room temperature to yield a unique crystalline product 2, 15-hydroxybenzo[g]benzo[6,7]isochromeno[4,3-c]isochromen-7(15H)-one. The product is proposed to result from facile air oxidation of NDA to a methyl ester in combination with benzoin condensation. Product 2 does not to form in the absence of air. The gHMBC spectrum of 2 distinguishes it from a possible alternative isomeric condensation product.

Cyclic Voltammetric Study of the Oxidation of Catechols in the Presence of Cyanide Ion

AbstractElectrochemical oxidation of catechols has been studied in the presence of cyanide ion as nucleophile in aqueous solution, by means of cyclic voltammetry and controlled‐potential coulometry. The results indicate that the participation of catechols in the Michael reaction with cyanide ion to form the corresponding o‐dihydroxybenzonitrile. Based on an EC mechanism, the homogeneous rate constants were estimated by comparing the experimental cyclic voltammetric responses with the digital simulated results.

Synthesis and Structure of Monomeric and Platinum-Bonded (1,10-Phenanthroline)thallium Complexes

Oxidative addition of (1,10-phenanthroline)thallium(III) complexes [Tl(phen)n(solv)]3+ (n = 1−2) (phen = 1,10-phenanthroline) to [Pt(CN)4]2− in DMSO, in the presence of cyanide ions and in the absence of cyanide ions yielded heterodinuclear metal−metal-bonded complexes, [(NC)5Pt−Tl(phen)n(solv)] and [(NC)4Pt−Tl(phen)n(solv)]+ (n = 0, 1, and 2), respectively. The presence of a direct Pt−Tl bond in the complex is evident by a very strong one-bond 195Pt−205Tl spin-spin coupling detected by 205Tl NMR: 1J = 94.0 kHz (1a), 84.2 kHz (2a), and 77.1 kHz (3a) corresponding to n = 0, 1, and 2 in [(NC)4Pt−Tl(phen)n(solv)]+, and 1J = 65.4 kHz (2b) and 62.5 kHz (3b) for n = 1 and 2, respectively, in [(NC)5Pt−Tl(phen)n(solv)]. The crystal structures of [(NC)5Pt−Tl(phen)(DMSO)3]·(DMSO) (2b), [(NC)5Pt−Tl(phen)2]·(DMSO)3 (3b), and [Tl(phen)2Cl2] (ClO4) (4) complexes were determined. Very short Pt−Tl bonds, 2.6296(3) and 2.6375(5) Å, are present in structures 2b and 3b, respectively. The corresponding force constants in the molecules in the solid state, 1.84 and 1.74 N/cm for 2b and 3b, respectively, were calculated using Raman stretching frequencies of the Pt−Tl vibrations, and are characteristic for a single, strong metal−metal bond. Electronic absorption spectra were recorded for selected compounds and the optical transition attributed to the metal−metal bond was assigned. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Self-Assembly of Tetranuclear Iron(II) Compounds by a Combination of Rod- and Clamp-Shaped Bridging Units

Dicyanomethanides, [RC(CN)2]− (1−), are bridging ligands with an angular clamp-type shape. In the tripod/iron(II) system, [tripod = CH3C(CH2PPh2)3], they form binuclear species with three of the clamp-type ligands bridging two iron centers. An appropriate stoichiometric mixture of the tripod ligand, iron(II) salts and the dicyanomethanide ligand leads to the exclusive formation of [tripodFe{μ-NC−C(R)−CN}3Fetripod]+ (3+). Altogether, seven constituent groups arrange themselves in this type of aggregate. The process of self-aggregation is distinctly modified by the presence of cyanide ions that may act as linear rod-type bridging ligands. Equimolar mixtures of tripod, iron(II) salts, dicyanomethanide ligands and cyanide form tetranuclear aggregates [{tripodFe}3{μ-NC−C(R)−CN}3{μ-CN}3FeX]+ (5+). In these species, the iron centers form a trigonal-pyramidal arrangement with three octahedrally coordinated low-spintripodiron(II) entities in the basal plane and a tetrahedrally coordinated high-spin iron(II) at the apex. The iron centers in the basal plane are connected by μ2-bridging dicyanomethanide ligands. The apical iron center is coordinated by the N-termini of three cyano ligands, which complete the octahedral coordination of the basal low-spin iron(II) centers. The fourth, external ligand X at the tetrahedrally coordinated high-spin iron(II) apex can be varied, but in most cases it is found to be a terminally coordinated dicyanomethanide entity. Without counting this variable ligand X, thirteen constituent groups of four different types selectively aggregate to form the cage compounds 5+. While the dinuclear compounds 3+ are diamagnetic, the tetranuclear species 5+ have magnetic moments close to the spin-only value of μs.o. = 4.9 μB, for tetrahedral high-spin iron(II). The Mossbauer spectra are in agreement with the description of 5+ above, which contain three low-spintripodiron(II) entities and one high-spin iron(II) center. The synthesis, spectroscopic data, cyclic voltammetric data, Mossbauer data and X-ray analytical data for a series of compounds of types 3+ and 5+ are presented in this paper.

Alkyl Xanthates: New Capping Agents for Metal Colloids. Capping of Platinum Nanoparticles

We investigate the properties of long-chain alkyl xanthate-capped platinum nanoparticles. First an uncapped platinum colloid, 4.0 ± 1 nm in diameter, is produced in an aqueous phase, and then the capping agent is added. The capped particles are hydrophobic and easily transfer into organic solvents. They can be dried and repetitively transferred to various organic liquids in a reversible manner. Xanthate-capped platinum colloids are more stable than the analogous thiol-capped particles (and certainly noncapped particles) toward chemical corrosion (by oxygen in the presence of cyanide ion) and are also stable on heating. These colloids exhibit a characteristic sharp absorption in the range 450−470 nm in addition to the extinction in the UV. This absorption might be assigned tentatively to a weak d−d transition of platinum observed in this region also for the PtCl62- salt and for its adduct with xanthate, though it is absent for uncapped Pt particles. The transition for the capped colloid, however, is much s...

Catalytic antibodies for complex reactions: hapten design and the importance of screening for catalysis in the generation of catalytic antibodies for the NDA/CN reaction.

Success in generating catalytic antibodies as enzyme mimics lies in the strategic design of the transition-state analog (TSA) for the reaction of interest, and careful development of screening processes for the selection of antibodies that are catalysts. Typically, the choice of TSA structure is straightforward, and the criterion for selection in screening is often binding of the TSA to the antibody in a microtiter-plate assay. This article emphasizes the problems of TSA design in complex reactions and the importance of selecting antibodies on the basis of catalysis as well as binding to the TSA. The target reaction is the derivatization of primary amines with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide ion. The desired outcome is selective catalysis of formation of the fluorescent derivative in preference to nonfluorescent side-products. In the study, TSA design was directed toward the reaction branch leading to the fluorescent product. Here, we describe a microtiter plate-based assay that is capable of detecting antibodies showing catalytic activity at an early stage. Of the antibodies selected, 36% showed no appreciable binding to any of the substrates tested, but did show catalytic activity in derivatizing one or more of the amino acids screened. In contrast, only two out of 77 clones that showed binding did not show catalysis. Thus, in this complex system, observation of binding is a good predictor of the presence of catalytic activity, and failure to observe binding is a poor predictor of the absence of catalytic activity.

Photosensitized oxidation, by single-electron transfer, of catharanthine and vindoline: a highly regio- and diastereoselective photocyanation reaction

The irradiation, by visible light, of (+)-catharanthine 1 and of (−)-16-O-acetylvindoline 5 in the presence of cyanide ion and a catalytic amount of a photosensitizer known to produce singlet oxygen leads to (+)-3β-cyanocatharanthine 3 and the new (−)-16-O-acetyl-3α-cyanovindoline 6. The complete stereostructural identification of these compounds has been ascertained by an accurate spectroscopic survey. High regio- and diastereoselectivities (de > 99%) are observed. Some experiments have been performed which confirm unambiguously that singlet oxygen is the oxidizing species in such photochemical conditions.

Olefin-Insertion Reaction between the Carbonyls of Benzils; Formation of 1,4-Diketones by Michael Additon Catalyzed by Cyanide Ion

Abstract Benzils (1) react with Michael addition acceptors (2) in the presence of cyanide ion as a catalyst to give 1,4-diketones (3), which are products of ethylene group insertion between the carbonyls of the benzils. The 1,4-diketones (3) are produced through the formation of the O-aroylmandelonitrile anion, followed by Michael addition and rearrangement of the aroyl group with decyanation.