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PubMedDate not supplied

Determination of iron in blood serum using flow injection with luminol chemiluminescence detection.

A simple and rapid fl ow injection method is reported for the determination of iron in blood serum after acid digestion with HNO3 and HClO4, based on luminol CL detection in the absence of added oxidant. The detection limit (3 s) was 1.0 nmol/L with a sample throughput of 120/h. The calibration graph was linear over the range 0.001-1.0 micromol/L (r2 = 0.9974), with relative standard deviations (RSD) (n = 4) in the range 3.2-5%. The effect of interfering cations (Ca(II), Mg(II), Cu(II), Cd(II), Pb(II), Mn(II), Zn(II), Ni(II), Co(II) and Fe(III)) and anions (Cl-, SO4(2-), HCO3-, NO3-, NO2-) were studied using a luminol CL system for Fe(II) determination. The method was applied to normal blood serum and the results (1.32 +/- 0.08-1.74 +/- 0.05 mg/L) were compared with those from a spectrophotometric reference method (1.34 +/- 0.06-1.80 +/- 0.10 mg/L), which agree fairly well with the overall reference range in blood.

Borates↗
PubMedDate not supplied

Study of the catalytic effect of PAR on the luminol-potassium ferricyanide reaction using a flow-injection chemiluminescence method.

We discovered that 4-(2-pyridylazo) resorcinol (PAR) has a strong catalytic effect on luminol-potassium ferricyanide chemiluminescence (CL). Results indicated that the chemiluminescence intensities at maximum light emission were linearly corrected with the concentration of PAR over the range 1.0 x 10(-5)-1.0 x 10(-7) mol/L. A detection limit of 5.7 x 10(-8) mol/L for PAR was achieved. It was found that some metal ions strongly affected this catalytic reaction. Based on this finding, the luminol-potassium ferricyanide-PAR reaction was developed for the determination of metal ions. The detection limits (S/N = 3) for Ni2+, Cr3+, Zn2+, Co2+ and Mn2+ were determined to be 1.0 x 10(-9) mol/L, 5.0 x 10(-9) mol/L, 5.0 x 10(-8) mol/L, 1.0 x 10(-9) mol/L and 1.0 x 10(-8) mol/L, respectively. In addition, the relative standard deviation values for these metal ion assays were in the range 0.82-2.72% (n = 6).

Catalysis↗
PubMedDate not supplied

Flow-injection chemiluminescence determination of catecholamines based on their enhancing effects on the luminol-potassium periodate system.

A rapid and sensitive chemiluminescence (CL) method using flow injection analysis is described for the determination of four catecholamines, dopamine, adrenaline, isoprenaline and noradrenaline, based on their greatly enhancing effects on the CL reaction of luminol-potassium periodate in basic solutions. The optimized chemical conditions for the chemiluminescence reaction were 1.0 x 10(-4) mol/L luminol and 1.0 x 10(-5) mol/L potassium periodate in 0.2 mol/L sodium hydroxide (NaOH). Under the optimized conditions, the calibration graphs relating the CL signal intensity (peak height) to the concentration of the analytes were curvilinear and they were suitable for determining dopamine, adrenaline, isoprenaline, and noradrenaline in the range 0.1-10 ng/mL, 0.1-100 ng/mL, 1-100 ng/mL and 5-50 ng/mL, respectively, with the relative standard deviations of 0.8-1.7%. The detection limits of the method are 0.02 ng/mL for dopamine, 0.01 ng/mL for adrenaline, 0.1 ng/mL for isoprenaline and 2.0 ng/mL for noradrenaline. The sampling frequency was calculated to be about 60/h. The selectivity of the method was good, because a series of common ions or excipients, such as K(+), Ba(2+), CO(3)(2-), NO(3)(-), SO(4)(2-), PO(4)(3-), sodium citrate, sodium bisulphite, oxidate dopamine, starch, lactose, carbamide and gelatin, could not produce interference when their concentrations were 1000-fold than those of dopamine. The present method was successfully applied to the determination of the four catecholamines in pharmaceutical injections.

Catecholamines↗
PubMedDate not supplied

Determination of thyroxine in pharmaceuticals using flow injection with luminol chemiluminescence inhibition detection.

A simple flow injection method is reported for the determination of thyroxine, based on its inhibition effect on luminol-iron(II) chemiluminescence in alkaline medium in the presence of molecular oxygen. The detection limits (2s) for d- and l-thyroxine are 0.08 and 0.1 mg/L, respectively, with a sample throughput of 100/h. The calibration data for d- and l-thyroxine over the range 0.2-1.0 mg/L gives correlation coefficients (r(2)) of 0.9915 and 0.984 with relative standard deviations (RSD; n = 4) in the range 1.2-2.8%. The effects of some organic compounds was studied on luminol-iron(II) CL system for thyroxine determination. The method was applied to pharmaceutical thyroxine tablets and the results obtained (in the range 50.5 +/- 2.0-51.6 +/- 1.2 microg l-thyroxine/tablet) were in reasonable agreement with the value quoted.

Flow Injection Analysis↗
PubMedDate not supplied

An assay for inorganic mercury(II) based on its post-catalytic enhancement effect on the potassium permanganate-luminol system.

A strong chemiluminescence (CL) response is observed when potassium permanganate solution is injected into basic luminol solution. When the CL reaction terminates, subsequent injection of Hg2+ solution into the reaction mixture results in a new CL reaction. Based on the post-catalytic enhancement effect of Hg2+ on the potassium permanganate-luminol system in basic media, a fast and simple CL-coupled flow injection analysis for the determination of Hg2+ was developed. In optimum conditions, CL intensity is proportional to Hg2+ concentration over the range 1.0 x 10(-8)-1.0 x 10(-5) g/mL, with a detection limit of 2.0 x 10(-9) g/mL. The relative standard deviation (RSD) is 3.6% for 1.0 x 10(-7) g/mL Hg2+ (n = 11). After pretreatment with sulphydryl cotton fibre, environmental water samples were analysed by the proposed method for total mercury determination with satisfactory results. The results were in good agreement with those given by hydride generation-cold vapour atomic absorption spectrometry (HG-CVAAS).

Catalysis↗
PubMedDate not supplied

Luminol chemiluminescence catalysed by colloidal platinum nanoparticles.

Platinum colloids prepared by the reduction of hexachloroplatinic acid with citrate in the presence of different stabilizers were found to enhance the chemiluminescence (CL) of the luminol-H(2)O(2) system, and the most intensive CL signals were obtained with citrate-protected Pt colloids synthesized with citrate as both a reductant and a stabilizer. Light emission was intense and reproducible. Transmission electron microscopy and X-ray photoelectron spectroscopy studies were conducted before and after the CL reaction to investigate the possible CL enhancement mechanism. It is suggested that this CL enhancement is attributed to the catalysis of platinum nanoparticles, which could accelerate the electron-transfer process and facilitate the CL radical generation in aqueous solution. The effects of Pt colloids prepared by the hydroborate reduction were also investigated. The application of the luminol-H(2)O(2)-Pt colloids system was exploited for the determination of compounds such as uric acid, ascorbic acid, phenols and amino acids.

Catalysis↗
PubMedDate not supplied

Catalytic effect of ferricyanide between myoglobin and luminol and effect of temperature.

Specific catalytic oxidation of oxymyoglobin (MbO(2)) and luminol by ferricyanide was studied in a flow-injection system. MbO(2) in different redox states (ferric and ferrous) was oxidized to Mb(Fe(III)) by ferricyanide, and then specific binding of the ferrocyanide anion to Mb(Fe(III)) to the His 119 (GH1) region accelerated the electron transfer between Mb(Fe(III)) and luminol, which produced a chemiluminescence (CL) signal at 425 nm. The increased CL emission was correlated with the myoglobin concentration in the range 0.16-7.5 microg/mL. Thermogravimetry and differential scanning calorimetry were used to investigate the temperature effects on this reaction. The results showed that the CL intensity in the presence of myoglobin changed considerably with heating in the range 15-50 degrees C, and the maximal CL intensity was observed at 40 degrees C, corresponding to the glass transition temperature of myoglobin. The effect of different ligands and interferences were also studied.

Catalysis↗
PubMedDate not supplied

Studies on PVP hydrogel-supported luminol chemiluminescence: 2. Luminometer calibration and potential analytical applications.

The use of poly(N-vinyl-2-pyrrolidone) (PVP) hydrogel-supported luminol chemiluminescence (CL) for the automatic determination of hydrogen peroxide and the quantification of the antiradical capacity of Trolox is described. The hydrogel containing luminol and hemin is prepared directly on a 96-well microplate and can be stored for up to 3 months without significant decrease in CL quantum yields. Furthermore, this system can also be used as a secondary light standard for the calibration of microplate luminometers.

Antioxidants↗
PubMed1992

Release of oxygen radicals by articular chondrocytes: a study of luminol-dependent chemiluminescence and hydrogen peroxide secretion.

We previously established that normal articular chondrocytes, like macrophages, express class II major histocompatibility antigens, present antigen, and induce mixed and autologous lymphocyte stimulation. In a recent study using the trapped indicator 2',7'-dichlorofluorescein diacetate, we were able to measure levels of intracellular hydrogen peroxide within normal articular chondrocytes (J Immunol 245:690-696, 1990). In the present study, we utilized the technique of chemiluminescence and the biochemical method of quantitating hydrogen peroxide release to measure the production of reactive oxygen intermediates by articular chondrocytes. Chondrocytes, in suspension or adherent to coverslips, showed luminol-dependent chemiluminescence that was dependent on the number and viability of cells. There was a dose-dependent increase in chemiluminescence in response to soluble stimuli, such as phorbol myristate acetate (PMA), concanavalin A (ConA), and f-Met-Leu-Phe (FMLP). Azide inhibited chemiluminescence, suggesting that the light emission in chondrocytes is myeloperoxidase dependent. The antioxidant, catalase, inhibited chemiluminescence but superoxide dismutase had no effect, suggesting that luminol-dependent chemiluminescence in chondrocytes mostly measured hydrogen peroxide. Chemiluminescence was also observed in fragments of live cartilage tissue, indicating that chondrocytes that are cartilage matrix bound can generate the respiratory burst response. Using the scopoletin oxidation assay, we confirmed the release of increasing amounts of hydrogen peroxide by chondrocytes exposed to interleukin-1, rabbit interferon, and tumor necrosis factor alpha. Tumor necrosis factor alpha had both priming and enhancing effects on reactive oxygen intermediate production by chondrocytes. Reactive oxygen intermediates have been shown to play a significant role in matrix degradation. We suggest that reactive oxygen intermediates produced by chondrocytes play an important role in the degradation of matrix in arthritis.

Animals↗
PubMed1986

Enhanced luminol-dependent chemiluminescence of stimulated rat alveolar macrophages by pretreatment with alveolar lining material.

Previous reports indicate that the in vitro bactericidal activity of rat alveolar macrophages (AM) is dependent on the lipid fraction (ALM-L) of the alveolar lining material (ALM). The present study demonstrates that luminol-dependent chemiluminescence of stimulated rat AM is increased when rat AM are preincubated in the ALM or in the ALM-L. Evidence is presented that oxidation of the unsaturated lipids is responsible for the increase. In addition to pretreatment with the ALM, cells were also pretreated in commercial preparations of several lipids found to be present in the ALM. Preincubation in these lipids produced a significant increase in the luminol-dependent chemiluminescence response. However, when a saturated lipid, dipalmitoyl phosphatidylcholine, was used no increase was found. Pretreatment in ALM did not increase the nitro blue tetrazolium dye reduction by the AM, nor was the phagocytosis of latex beads by the AM altered by the addition of the ALM.

Animals↗
PubMed1999

A myeloperoxidase-specific assay based upon bromide-dependent chemiluminescence of luminol.

Measurement of myeloperoxidase (MPO; EC 1.11.1.7) activity is often used as a marker of neutrophil infiltration into tissues. However, most enzymatic assays for MPO are susceptible to interference from other peroxidases (including eosinophil peroxidase, EPX) and hemoproteins (such as hemoglobin and myoglobin) present in the tissues. In this report, we describe a bromide-dependent chemiluminescence (Br-CL) assay that uses luminol as a chemiluminescence probe. The assay can distinguish between MPO and nonspecific peroxidase reactions. The MPO-specific reaction is believed to proceed in two steps: (i) the enzymatic generation of hypobromous acid (HOBr) from KBr and H(2)O(2) at pH 5 and (ii) the spontaneous reaction of HOBr and H(2)O(2) with luminol to give a Br-CL signal. The assay is sufficiently sensitive to allow detection of MPO in <100 human neutrophils. Other peroxidases and hemoproteins do not interfere with the Br-CL signal. Although EPX can also oxidize bromide to generate HOBr, activities of MPO and EPX can be distinguished at different pHs. As a demonstration of the utility of the Br-CL assay, MPO activity was measured in murine tumors known to be infiltrated with neutrophils. A statistically significant correlation was seen between MPO activity and histological neutrophil counts in the tumors (r = 0.69, P < 0.01, n = 14). The assay should have wide application for measuring the neutrophil content of tissues.

Bromides↗
PubMed1987

PHA- and Con A-induced chemiluminescence of human blood mononuclear cells and granulocytes in luminol or lucigenin.

Phytohemagglutinin (PHA) and concanavalin A (Con A) can evoke a chemiluminescence (CL) response both in granulocytes and blood mononuclear cells. We have used two parallel systems to compare the quantity and quality of oxygen radicals produced during activation. While the luminol-enhanced CL response is linked to the myeloperoxidase-H2O2-chloride system, the lucigenin-dependent light production measures only the superoxide radical. PHA produced higher CL response in the presence of luminol than with lucigenin. Con A showed high CL response only in the lucigenin-enhanced system. The results suggest that while Con A induces mostly superoxide production, the membrane stimulus evoked by PHA produces light through the myeloperoxidase-H2O2-halide system. Granulocytes are less sensitive to PHA than the blood mononuclear cells. The sensitivity of the responses to several scavengers and enzymes support the differential production of oxygen radicals following activation via these two lectins.

Acridines↗
PubMed1991

Toxicodynamics of tumour promoters of mouse skin. II. Binding to protein kinase C of some new diterpene esters and induction of luminol-enhanced chemoluminescence in mouse peritoneal neutrophils.

In binding competition assays using a protein kinase C preparation from mouse brain (particulate fraction) 3H-labelled 12-O-tetradecanoylphorbol-13-acetate (TPA), for a series of new diterpene esters (DTE) the relative binding affinity [rba = Kia(TPA)/Kia(DTE)] in relation to TPA was determined. A wide range of values was noticed, some of the DTE binding more strongly than TPA (rba greater than 1), others binding less strongly than TPA (rba less than 1) In comparative terms, competition for specific binding sites appears to correlate better with irritant than with promoting activity of the DTE. Using mouse peritoneal neutrophils, binding of [3H]-TPA was determined by a modification of the "cold-acetone filter assay"; saturation of high-affinity sites (Kda = 0.2 nM) was obtained at concentrations less than or equal to 1 nM, but there was also evidence for specific binding at "low-affinity" sites (Kda = 26 nM). Induction of chemoluminescence in the presence of luminol in mouse peritoneal neutrophils with a set of DTE usually elecited two peaks; at concentrations greater than or equal to 10 nM DTE a short-lived, "spike-like" response lasting only from 0 to about 5 min (phase A) its followed by a "plateau" response from about 5-120 min (phase B). This latter phase of chemoluminescence stimulation with luminol correlated well with the irritant potential of the DTE used. The sequence of the two phases can be inverted partially by using first TPA at 2,5 nM followed by a quick concentration increase to 100 nM; this indicates two different concentration-dependent events. As regards the intensity of the chemoluminescent response, quantitative but not qualitative differences between DTE were observed, which show some correlation with strong and weak tumour-promoting activity. Inhibition studies suggest the involvement of the myeloperoxidase/H2O2/Cl- system in the luminogenic response; it is suggested that the release of hypochlorite or a closely related oxidant may be instrumental in tumour promotion.

Animals↗
PubMed1982

Comparison of the effects of antioxidant non-steroidal anti-inflammatory drugs against myeloperoxidase and hypochlorous acid luminol-enhanced chemiluminescence.

The interaction of myeloperoxidase (MPO) with H2O2 and Cl- provides a potent antimicrobial/cytotoxic system for polymorphonuclear leukocytes (PMNs). MPO-related cytotoxicity may be associated with the formation of toxic oxidant MPO intermediates, HOCl, or both. MPO itself is able to oxidize drugs and cellular components. Non-steroidal anti-inflammatory drugs (NSAIDs) able to act as antioxidant free radical scavengers have recently been shown to inhibit luminol-enhanced chemiluminescence (CL) which results from the MPO-H2O2-Cl- reaction. CL is a measure of the activity of this reaction. At that time it was not clear whether the source of CL which these NSAIDs affected was HOCl or components of the initial MPO-H2O2-Cl- reaction. A NSAID antioxidant mechanism could affect MPO oxidant intermediates and HOCl. This study compares the effects of antioxidant NSAIDs, methylprednisone and free radical scavengers against MPO-based and NaOCl-based luminol-enhanced CL. Most NSAIDs which affected both MPO and NaOCl-CL appeared to share similar mechanisms, suggesting that MPO oxidant intermediates and HOCl are susceptible to NSAID effects. However, most NSAIDs were more effective against MPO-CL. The effect of these NSAIDs against MPO-CL followed the profile of NSAIDs effective in previous studies against PMN-CL. One exception to this was methylprednisone, which has no effect on PMN or MPO-CL, yet inhibited NaOCl-CL. This and other data suggest that MPO and not HOCl-related reactions are a major source of PMN-CL. Less effective NSAIDs affected NaOCl-CL better than MPO-CL. While both HOCl and MPO oxidant intermediates may be affected by NSAIDs, it appears that MPO oxidant intermediates or MPO itself are the primary target for NSAID antioxidant free radical scavenging mechanisms. These antioxidant effects impair the major killing system of the PMN and may be NSAIDs' primary anti-inflammatory mechanism. Although our data suggests the production of superoxide anion and hydroxyl radical from the MPO-H2O2-Cl- reaction, the actual presence or involvement of these free radical species is not confirmed herein.

Animals↗
PubMed2002

Photodynamic action of some sensitizers by photooxidation of luminol.

We report the development of a novel simple experimental method which allows the comparison of new photosensitizers based on their production of reactive oxygen species. A high-performance liquid chromatography (HPLC) assay permits the monitoring of several substances (sensitizer, reactant and oxidized end product) simultaneously on a single chromatogram. Photoreactions were monitored throughout their course by the HPLC assay surveying the sensitizers' efficiency of singlet oxygen production by the oxidative decomposition of luminol. Several photosensitizers were tested: Rose Bengal, Methylene Blue, Protoporphyrin IX, Photosan III, Photofrin, Hypericin and Pseudohypericin. Additionally, photoreactions were monitored by a standard pO(2) detection system. The measurements of the two detection methods were strongly correlated. Rose Bengal proved to be the most efficient photosensitizer, clearly decreasing the luminol concentration and causing a corresponding increase in aminophthalic acid. Our experiments show that when factors necessary for photochemical reactions are absent or are blocked (antioxidants), no reaction can be detected.

Dihematoporphyrin Ether↗
PubMed2003

A study of the chemiluminescence behavior of myoglobin with luminol and its analytical applications.

A chemiluminescence signal at 425 nm was observed when ferric state myoglobin was mixed with luminol in alkaline medium. Because the signal was remarkably enhanced in the presence of Fe(CN)6(4-), analytical applications were investigated in a flow-injection system. The increase in chemiluminescence was linearly dependent on myoglobin concentration in the range 0.1 to 100 nmol L(-1), and the limit of detection was 0.04 nmol L(-1) with relative standard deviation 3.2% (3 sigma). It was also found that binding of Mb with the ligands CN-, SCN-, and F- significantly inhibited the chemiluminescence reaction. The linear dynamic ranges for the ligands were 1.0-300.0, 0.1-3.0, and 0.5-100.0 nmol L(-1), and the limits of detection (S/N=3) 0.4, 0.04, and 0.2 nmol L(-1), for F-, CN-, and SCN-, respectively. The relative standard deviations were 5.32%, 6.13%, and 3.38% for 0.1 nmol L(-1) CN-, 0.5 nmol L(-1) SCN-, and 1.0 nmol L(-1) F-, respectively. At a flow rate of 2.0 mL min(-1) the assay could be accomplished in 1 min, including sampling and washing. The method has been successfully applied to the determination of myoglobin in human urine and F- in water samples. A possible mechanism of chemiluminescence production by myoglobin and luminol is presented.

Female↗
PubMed2006

Flow-injection analysis for the determination of total inorganic carbon and total organic carbon in water using the H2O2-luminol-uranine chemiluminescent reaction.

In the presence of carbonate and uranine, the chemiluminescent intensity from the reaction of luminol with hydrogen peroxide was dramatically enhanced in a basic medium. Based on this fact and coupled with the technique of flow-injection analysis, a highly sensitive method was developed for the determination of carbonate with a wide linear range. The method provided the determination of carbonate with a wide linear range of 1.0 x 10(-10)-5.0 x 10(-6) mol L(-1) and a low detection limit (S/N = 3) of carbonate of 1.2 x 10(-11) mol L(-1). The average relative standard deviation for 1.0 x 10(-9)-9.0 x 10(-7) mol L(-1) of carbonate was 3.7% (n = 11). Combined with the wet oxidation of potassium persulfate, the method was applied to the simultaneous determination of total inorganic carbon (TIC) and total organic carbon (TOC) in water. The linear ranges for TIC and TOC were 1.2 x 10(-6)-6.0 x 10(-2) mg L(-1) and 0.08-30 mg L(-1) carbon, respectively. Recoveries of 97.4-106.4% for TIC and 96.0-98.5% for TOC were obtained by adding 5 or 50 mg L(-1) of carbon to the water samples. The relative standard deviations (RSDs) were 2.6-4.8% for TIC and 4.6-6.6% for TOC (n = 5). The mechanism of the chemiluminescent reaction was also explored and a reasonable explanation about chemical energy transfer from luminol to uranine was proposed.

Carbon↗
PubMed1988

Enhancement of luminol-based immunodot and Western blotting assays by iodophenol.

The application of 4-iodophenol as a signal enhancer for luminol-based immunodot and Western blotting assays was investigated. Immunodetection of biotin-bovine serum albumin (BSA) using a rat anti-biotin antibody for immunodot binding and goat anti-biotin peroxidase conjugate for Western blotting assays was employed to demonstrate the signal enhancement attainable with 4-iodophenol. The addition of 4-iodophenol at a final working concentration of 52.2 microM to a light-emitting substrate, luminol, resulted in 3-fold and 10-fold signal enhancements for Western blotting and immunodot binding detection of biotin-BSA, respectively.

Animals↗