Improved high-performance liquid chromatographic determination of guanidino compounds by precolumn dervatization with ninhydrin and fluorescence detection

Ninhydrin has been investigated as a pre-column derivatization reagent for guanidino compounds. The reaction takes place under strongly alkaline conditions, followed by a second step at low pH and elevated temperature. This procedure yields derivatives with favourable fluorescence properties (excitation at 390 nm, emission at 470 nm). Amino acids do not react with ninhydrin under these conditions so that the method can easily be used for biological samples. Reversed-phase HPLC separations of the derivatives of several representative guanidino compounds in human blood have been achieved with gradients consisting of aqueous formic acid and methanol. Fluorescence detection yields quantification limits of about 20 microg L(-1). Hyphenation with electrospray mass spectrometry has been used to confirm the identity of the derivatives.     

ACTIVATION OF LUCIGENIN CHEMILUMINESCENCE BY SERRATIA MARCESCENS

Abstract Cell–free extracts and intact cells of Serratia marcescens were found to activate lucigenin (10,10 -dimethy1-9,9-biacridylium nitrate) chemiluminescence in the absence of either added H²O² or alkali. Light emission proceeded in alcoholic solvents and, in general, the intensity decreased with increasing length of the alcoholic carbon chain. Th e intensity of bacterially activated lucigenin chemiluminescence increased in a logarithmic linear manner with increasing methanol concentrations, maximum intensities occurring with 90% methanol. Other organic lucigenin solvents also supported the bacterially activated light emission process, although not to the same extent as 90% methanol. The addition of KOH to methanol failed to enhance chemiluminescence. The luminescent process was charaterized by the attainment of peak light emission three seconds after the initiation of the reaction, followed by rapid decay to a low constant light level. The bacterial activation of lucigening chemiluminescence was found to be enhanced by the inclusion by the inclusion of fluorescein in the neutral methanol solvent.     

Determination of superoxide dismutase and SOD-mimetic activities by a chemical system: Co2/H2O2/lucigenin

The bright chemiluminescence has been observed in the system: Co²⁺/hydrogen peroxide/lucigenin. The chemiluminescence intensity was directly proportional to either cobalt, hydrogen peroxide, or lucigenin concentrations. A procedure of determination of superoxide dismutase (SOD) activity by the chemiluminescence method in the cobalt–hydrogen peroxide–lucigenin system at pH 8.5 is suggested. A linear dependence was established between a relative chemiluminescence intensity and SOD concentration in the range of SOD concentrations between 0 and 4.5 nM, c _1/2 = 0.8 nM. The determination of SOD activity was performed in several tissue samples (rat plasma, erythrocyte hemolysate, and liver mitochondria). A technique of tissue sample preparation with the use of thermal inactivation of interfering proteins at 60 °C was used. The method was successfully applied for comparison of the efficiency of SOD mimetics.     

Electrogenerated chemiluminesence method for the determination of riboflavin at an ionic liquid modified gold electrode

A highly sensitive electrogenerated chemiluminescence (ECL) method for the determination of riboflavin was developed based on the enhancement of ECL intensity of lucigenin at room temperature ionic liquids (RTILs) modified gold electrode. RTILs modified gold electrode exhibited excellent electrochemical and ECL property to lucigenin system and the ECL intensity of lucigenin was greatly enhanced by riboflavin. The characterization of the RTILs modified electrode and the attractive performance of the sensitive ECL method for the determination of riboflavin were investigated. Under the optimized conditions, the ECL intensity was directly proportional to the concentration of riboflavin in the range from 5.0×10(-10) g/mL to 1.0×10(-8)g/mL with the detection limit of 1×10(-10) g/mL. The method has been applied to the determination of riboflavin in the pharmaceutical preparations with satisfactory recovery from 96% to 101%. This work demonstrates that the incorporation of ECL method with RTILs modified electrode is a promising strategy for the determination of organic compounds with high sensitivity and good reproducibility.     

光泽精与钨（Ⅲ）的流动注射－胶束增敏化学发光反应

采用了Jones柱在线还原钨（Ⅵ）为钨（Ⅲ），详细研究了钨（Ⅲ）与光泽精的化学发光反应，加入乳化剂OP能明显提高发光的信噪比，基于此建立了痕量钨的流动注射化学发光分析法。该法线性范围为1×10－6～1×10－2 g·L－1, 检出限为5×10－7 g·L－1 , 相对标准偏差为2.0％（5×10－5 g·L－1, n=11）。文中还探讨了反应机理。     

Synthesis of dendritic platinum nanoparticles/lucigenin/reduced graphene oxide hybrid with chemiluminescence activity

Multifunctional hybrid: A dendritic platinum nanoparticle/lucigenin/reduced graphene oxide (RGO) hybrid with chemiluminescence (CL) activity was prepared for the first time by using lucigenin as a linker through simultaneous reduction of H(2) PtCl(4) and a lucigenin-functionalized graphene oxide composite by sodium borohydride (see scheme). The hybrid may have potential applications as a CL sensor, in catalysis, energy conversion, and opto-electronic systems.     

Flow-injection determination of trace amounts of dopamine by chemiluminescence detection

A flow-injection analysis (FIA) for the determination of dopamine has been developed. The method is based on the inhibition effect of dopamine on the iron(II)-induced chemiluminescence (CL) of 10,10'-dimethyl-9,9'-biacridinium dinitrate (lucigenin). The presence of a non-ionic surfactant, polyoxyethylene (23) lauryl ether (Brij 35), caused an increase in the inhibition effect. The present method allows the determination of dopamine over the range 1x10(-8)-2x10(-7) mol dm(-3). The relative standard deviation was 0.7% for eight determinations of 6x10(-8) mol dm(-3) dopamine. The detection limit (S/N=3) was 2x10(-9) mol dm(-3) with the sampling rate of 40 samples h(-1). The effect of other catecholamines and compounds of similar structure on the lucigenin CL reaction was studied: quinone, hydroquinone, norepinephrine, pyrocatechol and l-dopa suppressed the CL intensity.     

Ion-exchange chromatographic separation and fluorometric detection of guanidino compounds in physiologic fluids.

A high-performance liquid chromatographic procedure has been developed for the separation and fluorometric detection of guanidino compounds in physiologic fluids. All guanidino compounds were separated on a 17 X 0.46 cm cation-exchange column using a stepwise pH gradient. The chromatographic system was designed to enable the use of the specific reagent 9,10-phenanthrenequinone as a means of monitoring the guanidino compounds of physiologic fluids. This new analytical method is so sensitive that it enables the analysis at the picomole level. Our automatic guanidino-compound analyzer was successfully applied to the quantitative determination of all guanidino compounds in physiologic fluids from normal controls and uremic patients.     

Chemiluminescence from the oxidation of urea and ammonia with hypobromite and N-bromosuccinimide

The spectral distribution for the chemiluminescent oxidation of ammonia with hypobromite is significantly different to that for the oxidation of ammonia with N-bromosuccinimide. Therefore, in contrast to the assumptions of several authors, the action of N-bromosuccinimide is not solely derived from the in situ formation of hypobromite. Neither the oxidation of urea with hypobromite nor the oxidation of urea with N-bromosuccinimide involves an initial hydrolysis of urea to ammonia in the alkaline solution. However, these two reactions lead to a common emitter. The addition of xanthene dyes, such as dichlorofluorescein, enhance the chemiluminescence intensity by energy transfer to the efficient fluorophore, but reaction between the sensitiser and hypobromite can result in a significant increase in the background signal. A list of potential interferences has been compiled; particular attention was paid to guanidino compounds, as the chemiluminescence accompanying the oxidation of this functional group has not been previously discussed.     

Determination of guanidino compounds by anion-exchange chromatography and amperometric detection

Guanidino compounds were separated and determined by anion-exchange chromatography and electrochemical detection using a basic aqueous eluent and a nickel working electrode. It was found necessary to use a sample clean-up procedure prior to chromatographic analysis of uremic dialysate and serum samples. The effect of eluent hydroxide concentration on the retention of guanidino compounds was studied. Quantitative calibration showed that working curves were non-linear. Electrochemical detection for guanidino compounds with a nickel working electrode, while not selective, has high detection sensitivity. Detection limits for guanidino compounds ranged from 3 to 12 pmol.     

Chemiluminescence high performance liquid chromatography of corticosteroids using lucigenin as post-column reagent

A chemiluminescence high performance liquid chromatographic method for the determination of corticosteroids and tetrahydrocorticosteroids has been developed. Corticosteroids and their metabolites extracted from urine samples were separated using an ODS column and a mixture of methanol + water + 0.01 M sodium acetate solution (70:30:5) as eluent. The eluent from the column was mixed with the chemiluminescent solution containing lucigenin and Triton X-100 and a 0.28 M KOH solution by pumps and monitored by a chemiluminescence detector. No interference was encountered and the method is both precise and reproducible.     

Effect of vitamins C and P on the chemiluminescence of lucigenin in model membrane structures

The chemiluminescence quantum yields of the lucigenin light reaction in didodecyldimethylammonium bromide lamelar aggregates are affected by the presence of vitamins C and P. A dramatic lowering of the chemiluminescence quantum yield is observed in the presence of sodiumL-ascorbate, the reaction is virtually unaffected by nicotinamide and the quantum yields are raised by almost a factor of 2 in the presence of sodium nicotinate at high concentrations.     

Generation of superoxide anions during the reaction of guanidino compounds with methylglyoxal

Uremic toxins are accumulated in the blood of patients with chronic renal failure (CRF), although alteration of the toxicity by the interaction of various uremic retention products has not been precisely clarified. In this study, we found that cytochrome c added to incubation mixtures containing guanidino compounds and methylglyoxal in phosphate buffer solution (pH 7.4) resulted in reduction of cytochrome c. Superoxide anions were generated from incubation mixtures of each guanidino compound with methylglyoxal, because the reduction was inhibited by the addition of superoxide dismutase. The incubation mixture containing each guanidino compound and methylglyoxal had different rates of generation of the superoxide anion from other mixtures. A relatively higher superoxide anion formation rate was observed in the incubation mixture containing Arg and methylglyoxal (7.9 +/- 0.5nmol x m(-1) x min(-1)), or in the incubation mixture containing methylguanidine and methylglyoxal (6.3 +/- 0.6 nmol x ml(-1) min(-1)). These findings suggest that interactions of various uremic retention products which accumulate in the blood of uremic patients may generate reactive oxygen species and may be involved in the oxidative stress observed in CRF patients. The addition of aminoguanidine, which is known to inhibit the formation of advanced glycation end products, to a mixture of guanidino compounds and methylglyoxal inhibited reactions between guanidino compounds and methylglyoxal.     

CHEMILUMINESCENCE IN THE OXIDATION OF 6-HYDROXYDOPAMINE: EFFECTS OF LUCIGENIN, SCAVENGERS OF ACTIVE OXYGEN, METAL CHELATORS AND THE PRESENCE OF OXYGEN

Abstract— Maximum chemiluminescence in a system containing 6-hydroxydopamine (6-OHDA) and H₂O₂ required the addition of Fe²⁺:EDTA, oxygen, and lucigenin. In this system luminescence was strongly inhibited by catalase (91% inhibition) or 50 m M mannitol (83%), whereas superoxide dismutase or ascorbate did not significantly change the reaction rate. In the absence of lucigenin, 50 m M mannitol (78%), catalase (76%), or ascorbate (73%) inhibited strongly, while superoxide dismutase inhibited by 60%. Removing EDTA from the lucigenin-containing system caused a 79% decrease in luminescence, while the substitution of desferoxamine for EDTA decreased luminescence by 55%. In the presence of desferoxamine plus EDTA the luminescence increased by 30% in comparison with that seen with EDTA alone. Luminescence in the system containing 6-hydroxydopamine, H₂O₂, Fe²⁺:EDTA and lucigenin required the presence of oxygen (93% inhibition anaerobically), consistent with a mechanism involving reductive oxygenation of the lucigenin. It is concluded that luminescence in the presence of lucigenin involves a substantial contribution from H₂O₂ and Fe²⁺ mediated by a mannitol-sensitive intermediate (conceivably Fenton-derived hydroxyl radicals). In the absence of lucigenin, superoxide and an ascorbate-labile component are additional important participants in the process.     

Solvent effects in the reaction of lucigenin with basic hydrogen peroxide: Chemiluminescence spectra in mixed polar solvents

Summary The chemiluminescent reaction of lucigenin with basic hydrogen peroxide has been studied in several mixtures of water with the cosolvents methanol, ethanol, 1-propanol, dimethylformamide, and dimethylsulfoxide. The chemiluminescence spectra depend on the cosolvent and its concentration in the reaction medium. With increasing cosolvent concentration, the chemiluminescence shifts to lower wavelengths. For similar cosolvents, the size of this shift increases with decreasing dielectric constant. In high-cosolvent-concentration mixtures, the chemiluminescence matches the fluorescent emission of N-methylacridone. Chemiluminescence from low-cosolvent-concentration mixtures is explained as the sum of the lucigenin and N-methylacridone fluorescent emissions, the lucigenin emission probably being a consequence of energy transfer from N-methyl-acridone. The cosolvent inhibits this energy transfer. These observations, taken together with our previous kinetic results, indicate that the reaction mechanism is the same in all the studied reaction media.

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Lösungsmitteleffekte bei der Reaktion von Lucigenin mit basischem Hydrogenperoxid: Chemilumineszenzspektren in gemischten polaren Lösungsmitteln

Zusammenfassung Die Chemilumineszenzreaktion von Lucigenin mit basischem Hydrogenperoxid wurde in verschiedenen Mischungen von Wasser mit Methanol, Ethanol, 1-Propanol, Dimethylformamid oder Dimethylsulfoxyd untersucht. Die Chemilumineszenzspektren hängen vom organischen Kosolvens und dessen Konzentration im Reaktionsmedium ab. Mit ansteigender Konzentration ergeben sich in der Chemilumineszenz Verschiebungen zu größeren Wellenlängen. Für ähnliche Kosolventien steigt diese Verschiebung mit kleineren Dielektrizitätskonstanten an. Bei hohen Kosolvenskonzentrationen gleicht die Chemilumineszenz der Fluoreszenzemission von N-Methylacridon. Die Chemilumineszenz bei kleinen Kosolvenskonzentrationen kann als die Summe der Fluoreszenzemission von Lucigenin und N-Methylacridon erklärt werden, wobei die Lucigeninemission vermutlich eine Folge eines Energietransfers von N-Methylacridon ist. Das Kosolvens verhindert diesen Energietransfer. Diese Beobachtungen, zusammen mit früheren kinetischen Resultaten, erlauben den Schluß, daß der Reaktionsmechanismus in allen Reaktionsmedien der gleiche ist.

     

Platinum nanoparticle-catalyzed lucigenin–hydrazine chemiluminescence

It was found that lucigenin alkaline solution could react with hydrazine in the presence of Pt nanoparticles to generate strong chemiluminescence (CL) centered at 480 nm. In order to explore the CL mechanism, UV–visible spectra, X-ray photoelectron spectra studies before and after the CL reaction were carried out. The effects of O₂ and superoxide dismutase (SOD) on the CL reaction were examined. The catalytic effect of Pt NPs on the hydrazine–O₂ reaction was studied. A possible mechanism is proposed to be due to that Pt NPs catalyzed the reaction between hydrazine and the dissolved oxygen under alkaline conditions to yield hydroperoxide species and superoxide radical anion, which further oxidized lucigenin to produce CL emission. Moreover, the effects of some organic compounds containing hydroxyl (OH), carboxyl (COOH), carbonyl (CO), amino (NH₂), or sulfur groups on the lucigenin–hydrazine–Pt NPs CL system were tested. Thiol-containing compounds such as cysteine (Cys), glutathione (GSH), homocysteine (Hcy), and 6-mercaptopurine (6-MP) were observed to greatly enhance the CL intensity. It is suggested that the CL enhancement might be due to the fact that thiol-containing compounds could facilitate the electron transfer process under the catalysis of Pt nanoparticles and accelerate the generation of OH and O₂^? radicals, leading to the strong CL.     

液相色谱化学发光检测法的新进展

本文评述了近年来液相色谱化学发光检测法的新进展，内容涉及各类化学发光发反应，生物发光反应和电致化学发光反应同色谱体系的偶合方式，仪器设计，多种无机，有机，生物大分子和生物活性物质的分析方法及其在环境，生物医学科学和生命科学中的应用和发展方向。引用文献１６８篇。     

Chemiluminescent Logic Gates Based on Functionalized Gold Nanoparticles/Graphene Oxide Nanocomposites

Label‐free logic gates (AND, OR, and INHIBIT) based on chemiluminescence (CL) as new optical readout signal have been developed by taking advantage of the unique CL activity of luminol‐ and lucigenin‐functionalized gold nanoparticles/graphene oxide (luminol‐lucigenin/AuNPs/GO) nanocomposites. It was found that Fe²⁺ ions could induce the CL emission of luminol‐lucigenin/AuNPs/GO nanocomposites in alkaline solution. On this basis, by using Fe²⁺ ions and NaOH as the inputs and the CL signal as the output, an AND logic gate was fabricated. When the initial reaction system contained luminol‐lucigenin/AuNPs/GO nanocomposites and NaOH, either Fe²⁺ ions or Ag⁺ ions could react with the luminol‐lucigenin/AuNPs/GO nanocomposites to produce a strong CL emission. This result was used to design an OR logic gate using Fe²⁺ ions and Ag⁺ ions as the inputs and CL signal as the output. Moreover, two INHIBIT logic gates for Fe²⁺ and Ag⁺ were also developed using by NaClO and L ‐cysteine as their CL inhibitors, respectively. Furthermore, the proposed logic gates were successfully used to detect Fe²⁺, Ag⁺, and L ‐cysteine, respectively. The developed logic gates may find future applications in sensing, clinical diagnostics, and environmental monitoring.     

The reaction between phloroglucinol and vic polycarbonyl compounds: extension and mechanistic elucidation of Kim's synthesis for bipolarofacial bowl-shaped compounds

Kim's serendipitous synthesis of a novel cavitand by the one-pot reaction between phloroglucinol and ninhydrin was revisited and extended. A much deeper cavitand was obtained by replacing ninhydrin with benzo[f]ninhydrin. Performing the reaction in a stepwise manner, employing both ninhydrin and benzo[f]ninhydrin, provided ‘mixed bowls’ of lower symmetry. Other cyclic polyketones, such as 1,2-indanedione and alloxan, form with phloroglucinol only partially closed structures. Crystallographic studies of the intermediate compounds in this reaction confirm Kim's postulate that the bowl formation involves hemiketal ring-openings and rearrangements.