Oscillating chemiluminescence with thiosemicarbazide in a batch reactor

Oscillating chemical reactions are complex systems involving a large number of chemical species. In oscillating chemical reactions, some species, usually reaction intermediates, exhibit fluctuations in their concentration. In this report, a novel slowly‐damped oscillating chemiluminescence produced by the addition of thiosemicarbazide (TSC) to the oscillating system H₂O₂–KSCN–CuSO₄–NaOH was investigated. Narrow and slightly asymmetric light pulses of 1.5 s half‐width are emitted at 440 nm, with an oscillation period of 22–363 s, an induction period of 9–397 s and an emitted light time of 700–1500 s, depending on reagent concentrations. In this study the dependence of the induction period and the oscillation period on the reagent concentrations was investigated and both parameters were plotted with respect to reagent concentrations. Copper concentration showed a significant effect on the oscillation period. A possible mechanism for the oscillating chemiluminescence reaction is discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Studies of visible oscillating chemiluminescence with a luminol–H2O2–KSCN–CuSO4–NaOH system in batch reactor

Oscillating chemical reactions are complex systems involving a large number of chemical species. In oscillating chemical reactions some species, usually reaction intermediates, exhibit fluctuation in concentration. Visible oscillating chemiluminescence, produced by the addition of luminol (3‐aminophthalhydrazide) to the oscillating system H₂O₂–KSCN–CuSO₄–NaOH, was investigated. In this study the effect of varying the concentration of H₂O₂, KSCN, CuSO₄, NaOH and luminol was investigated in a batch reactor. We showed that the concentration of all components involved in the oscillating chemilumenscent reaction influenced the light intensity and the oscillation period. Copyright © 2002 John Wiley & Sons, Ltd.     

Studies of visible oscillating chemiluminescence in luminol–H2O2–KSCN–CuSO4 system using (2‐hydroxyethyl) trimethylammonium hydroxide

Visible oscillating chemiluminescence (CL) of luminol–H₂O₂–KSCN–CuSO₄ was studied using the organic base (2‐hydroxyethyl)trimethylammonium hydroxide. The effect of concentrations of luminol, H₂O₂, KSCN, CuSO₄ and the base were investigated in a batch reactor. This report shows how the concentration of components involved in the oscillating CL system influenced the oscillation period, light amplitude and total time of light emission. The oscillating CL with different bases was also investigated. Results indicated that using 2‐HETMAOH causes regular oscillating CL with nearly the same oscillating period. Copyright © 2008 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescent determination of estrogen benzoate using the tris(1,10‐phenanthroline) ruthenium(II)–permanganate system

Chemiluminescence (CL) detection for the determination of estrogen benzoate, using the reaction of tris(1,10–phenanthroline)ruthenium(II)–Na₂SO₃–permanganate, is described. This method is based on the CL reaction of estrogen benzoate (EB) with acidic potassium permanganate and tris(1,10–phenanthroline)ruthenium(II). The CL intensity is greatly enhanced when Na₂SO₃ is added. After optimization of the different experimental parameters, a calibration graph for estrogen benzoate is linear in the range 0.05–10 µg/mL. The 3 s limit of detection is 0.024 µg/mL and the relative standard deviation was 1.3% for 1.0 µg/mL estrogen benzoate (n = 11). This proposed method was successfully applied to commercial injection samples and emulsion cosmetics. The mechanism of CL reaction was also studied. Copyright © 2011 John Wiley & Sons, Ltd.     

Large enhancement of oscillating chemiluminescence with [Ru(bpy)3]2+‐catalyzed Belousov–Zhabotinsky reaction in the presence of tri‐n‐propylamine

Oscillating chemiluminescence enhanced by the addition of tri‐n‐propylamine (TPrA) to the typical Belousov–Zhabotinsky (BZ) reaction system catalyzed by ruthenium(II)tris(2.2'‐bipyridine)(Ru(bpy)₃²⁺) was investigated using a luminometry method. The [Ru(bpy)₃]²⁺/TPrA system was first used as the catalyst for a BZ oscillator in a closed system, which exhibited a shorter induction period, higher amplitude and much more stable chemiluminescence (CL) oscillation. The effects of various concentrations of TPrA, oxygen and nitrogen flow rate on the oscillating behavior of this system were examined. In addition, the CL intensity of the [Ru(bpy)₃]²⁺/TPrA–BZ system was found to be inhibited by phenol, thus providing a way for use of the BZ system in the determination of phenolic compounds. Moreover, the possible mechanism of the oscillating CL reaction catalyzed by [Ru(bpy)₃]²⁺/TPrA and the inhibition effects of oxygen and phenol on this oscillating CL system were considered. Copyright © 2012 John Wiley & Sons, Ltd.     

Perturbation of the tris(2,2′‐bipyridine) ruthenium(II)‐catalyzed Belousov–Zhabotinsky oscillating chemiluminescence reaction by l‐cysteine and its application

Perturbation of the tris(2,2′‐bipyridine)ruthenium(II) [Ru(bpy)₃²⁺]‐catalyzed Belousov–Zhabotinsky (BZ) oscillating chemiluminescence (CL) reaction induced by l ‐cysteine was observed in the closed system. It was found that the CL intensity was decreased in the presence of l ‐cysteine. Meanwhile, oscillation period and oscillating induction period were prolonged. The sufficient reproducible induction period was used as parameter for the analytical application of oscillating CL reaction. Under the optimum conditions, the changes in the oscillating CL induction period were linearly proportional to the concentration of l ‐cysteine in the range from 8.0 × 10^?7 to 5.0 × 10^?5 mol L^?1 (r = 0.997) with a detection limit of 4.3 × 10^?7 mol L^?1. The possible mechanism of l ‐cysteine perturbation on the oscillating CL reaction was also discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

In vitro screening of Fe2+‐chelating effect by a Fenton's reaction–luminol chemiluminescence system

In vitro screening of a Fe²⁺‐chelating effect using a Fenton's reaction–luminol chemiluminescence (CL) system is described. The luminescence between the reactive oxygen species generated by the Fenton's reaction and luminol was decreased on capturing Fe²⁺ using a chelator. The proposed method can prevent the consumption of expensive seed compounds (drug discovery candidates) owing to the high sensitivity of CL detection. Therefore, the assay could be performed using small volumes of sample solution (150 μL) at micromolar concentrations. After optimization of the screening conditions, the efficacies of conventional chelators such as ethylenediaminetetraacetic acid (EDTA), diethylentriaminepentaacetic acid (DETAPAC), deferoxamine, deferiprone and 1,10‐phenanthroline were examined. EC₅₀ values for these compounds (except 1,10‐phenanthroline) were in the range 3.20 ± 0.87 to 9.57 ± 0.64 μM (n = 3). Rapid measurement of the Fe²⁺‐chelating effect with an assay run time of a few minutes could be achieved using the proposed method. In addition, the specificity of the method was discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Chemiluminescence determination of promazine in human serum and drug formulations using Ru(phen)32+–Ce(IV) system and a chemometrical optimization approach

A new chemiluminescence (CL) method using flow injection has been described for the rapid and sensitive determination of promazine hydrochloride (PMH). The method is based on the CL reaction of PMH with tris(1,10 phenanthroline)ruthenium(II), [Ru(phen)₃²⁺] and Ce(IV) in sulfuric acid medium. Effects of chemical variables were investigated employing central composite design and response surface methodology. Under the optimum conditions, the CL intensity was proportional to the concentration of the drug in solution over the ranges 0.020–0.32 and 0.32–32 µg/mL. The limit of detection (signal‐to‐noise ratio = 3) was 0.012 µg/mL. The method was applied successfully to the determination of PMH in drug formulations and human serum (recovery percentages between 96.7 and 105.0%). The relative standard deviation for 11 replicate determinations of 1.5 µg/mL of PMH was 1.7%. The minimum sampling rate was 100 samples per hour. Copyright © 2009 John Wiley & Sons, Ltd.     

Analysis of fexofenadine in pharmaceutical formulations using tris(1,10‐phenanthroline)–ruthenium(II) peroxydisulphate chemiluminescence system in a multichip device

A simple, rapid and sensitive method has been developed for the analysis of fexofenadine (FEX) in pharmaceutical formulations, using a tris(1,10‐phenanthroline)–ruthenium(II) [Ru(phen)₃²⁺] peroxydisulphate chemiluminescence (CL) system in a multichip device. Various parameters that influence the CL signal intensity were optimized. These included pH, flow rates and concentration of reagents used. Under optimum conditions, a linear calibration curve in the range 0.05–5.0 µg/mL was obtained. The detection limit was found to be 0.001 µg/mL. The procedure was applied to the analysis of FEX in pharmaceutical products and was found to be free from interference from concomitants usually present in these preparations. Copyright © 2011 John Wiley & Sons, Ltd.     

Chemiluminescence determination of chlorpheniramine using tris(1,10‐phenanthroline)–ruthenium(II) peroxydisulphate system and sequential injection analysis

A sequential injection (SI) method was developed for the determination of chlorpheniramine (CPA), based on the reaction of this drug with tris(1,10‐phenanthroline)–ruthenium(II) [Ru(phen)₃²⁺] and peroxydisulphate (S₂O₈^2–) in the presence of light. The instrumental set‐up utilized a syringe pump and a multiposition valve to aspirate the reagents [Ru(phen)₃²⁺ and S₂O₈^2–] and a peristaltic pump to propel the sample. The experimental conditions affecting the chemiluminescence reaction were systematically optimized, using the univariate approach. Under the optimum conditions linear calibration curves of 0.1–10 µg/ml were obtained. The detection limit was 0.04 µg/ml and the relative standard deviation (RSD) was always < 5%. The procedure was applied to the analysis of CPA in pharmaceutical products and was found to be free from interferences from concomitants usually present in these preparations. Copyright © 2008 John Wiley & Sons, Ltd.     

Investigations of different chemiluminescent peaks in H2O2–SCN−–Cu2+–OH−–luminol flow system

In the H₂O₂–SCN^?–Cu²⁺–OH^?–luminol oscillatory system of chemiluminescence, the effects of the ingredient concentrations, temperature, flow rate and complexing agent on the oscillatory dynamics were investigated in a continuous‐flow stirred tank reactor (CSTR). The dynamical structure of two peaks during a period was discussed in detail. By addition of EDTA to the oscillating system, the peak I height decreased sharply while the peak II height was little affected, and the period kept constant. This may be due to the fast reaction between Cu(II) and EDTA and the highly stable complex Cu(II)–EDTA. From the experimental study and mechanism analysis, the chemiluminescent peak I corresponds to Cu(II) → Cu(I) transformation and the peak II corresponds to the Cu(I) → Cu(II) transformation process. The key species involving in the two‐transformation process are inferred to be superoxide radical and hydroxyl radical. Copyright © 2010 John Wiley & Son, Ltd.     

Study of the enhancement of a new chemiluminescence reaction and its application to determination of β‐lactam antibiotics

An enhanced thiosemicarbazide(TSC)–H₂O₂ chemiluminescence (CL) system was established and proposed as a new analytical method for determination of β‐lactam antibiotics, ampicillin sodium and amoxicillin at microgram levels. The method is based on the inhibition of CL emission accompanying oxidation of TSC by H₂O₂ in alkaline medium. The effect of anionic, cationic, and non‐ionic surfactants on the CL emission of the system was studied. Both N‐cetyl‐N,N,N‐trimethylammonium bromide (CTMAB) and Triton X‐100, unlike sodium dodecyl sulfate (SDS), reinforced the CL intensity and were efficient to approximately the same level. The effect of the presence of eight non‐aqueous solvents on the CL system was also investigated. Upon addition of both of the non‐ionic surfactant, Triton X‐100, and the non‐aqueous solvent, N,N‐dimethyl formamide (DMF), the intensity of the CL reaction was increased 100‐fold. This method allows the measurement of 25–545 µg amoxicillin, and 35–350 µg ampicillin sodium. The detection limits are 8 µg for amoxicillin and 9 µg for ampicillin sodium. The relative standard deviations of six replicate measurements of 200 µg amoxicillin and 200 µg ampicillin sodium were 1.9 and 2.1%, respectively. The effect of foreign species on the determination of amoxicillin and ampicillin sodium was also examined. The proposed method was successfully applied to the determination of ampicillin sodium and amoxicillin in some pharmaceutical dosage forms. Copyright © 2008 John Wiley & Sons, Ltd.     

Determination of ampicillin sodium using the cupric oxide nanoparticles–luminol–H2O2 chemiluminescence reaction

A simple and sensitive chemiluminescence (CL) method has been developed for the determination of ampicillin sodium at submicromolar levels. The method is based on the inhibitory effect of ampicillin sodium on the cupric oxide nanoparticles (CuO NPs)–luminol–H₂O₂ CL reaction. Experimental parameters affecting CL inhibition including concentrations of CuO NPs, luminol, H₂O₂ and NaOH were optimized. Under optimum conditions, the calibration plot was linear in the analyte concentration range 4.0 × 10^‐7–4.0 × 10^‐6 mol/L. The limit of detection was 2.6 × 10^‐7 mol/L and the relative standard deviation (RSD) for six replicate determinations of 1 × 10^‐6 mol/L ampicillin sodium was 4.71%. Also, X–ray diffraction (XRD) and transmission electron microscopy (TEM) analysis were employed to characterize the CuO NPs. The utility of the proposed method was demonstrated by determining ampicillin sodium in pharmaceutical preparation. Copyright © 2013 John Wiley & Sons, Ltd.     

Determination of oxytetracycline hydrochloride in milk and egg white samples using Ru(bipy)32+–Ce(SO4)2 chemiluminescence

A novel, rapid and sensitive chemiluminescence (CL) method for the determination of oxytetracycline hydrochloride (OTCH) is described in this paper. The presented method was based on the fact that OTCH could immensely enhance the CL of the reaction of cerium sulfate and tris(2,2‐bipyridyl) ruthenium (II) in acidic medium. Under optimal experimental conditions, CL intensity was favorably linear for OTCH in the range 5.0 × 10^?7 to 5.0 × 10^?5 g/ml, with a detection limit of 1.5 × 10^?7 g/ml (S/N = 3). The relative standard detection was 4.76% for 5.0 × 10^?6 g/ml (n = 11). This method was successfully applied to the analysis of OTCH in milk and egg white samples. According to the results of the kinetic curves for OTCH in the Ru(bipy)₃²⁺–Ce(SO₄)₂ CL system, together with CL and ultraviolet (UV)–visible spectra, the possible mechanism of the CL reaction is discussed briefly.     

Employment of 4‐(1,2,4‐triazol‐1‐yl)phenol as a signal enhancer of the chemiluminescent luminol–H2O2–horseradish peroxidase reaction for detection of hepatitis C virus in real samples

Highly sensitive detection of hepatitis C virus (HCV) in serum is a key method for diagnosing and classifying the extent of HCV infection. In this study, a p‐phenol derivative, 4‐(1,2,4‐triazol‐1‐yl)phenol (4‐TRP), was employed as an efficient enhancer of the luminol–hydrogen peroxide (H₂O₂)–horseradish peroxidase (HRP) chemiluminescence (CL) system for detection of HCV. Compared with a traditional enhancer, 4‐TRP strongly enhanced CL intensity with the effect of prolonging and stabilizing light emission. The developed CL system was applied to detecting HCV core antigen (HCV‐cAg) using a sandwich structure inside microwells. Our experimental results showed that there was good linear relationship between CL intensity and HCV‐cAg concentration in the 0.6–3.6 pg/mL range (R = 0.99). The intra‐ and inter‐assay coefficients of variation were 4.5–5.8% and 5.0–7.3%, respectively. In addition, sensitive determination of HCV‐cAg in serum samples using the luminol–H₂O₂–HRP–4‐TRP CL system was also feasible in clinical settings. Copyright © 2015 John Wiley & Sons, Ltd.     

Chemiluminescence method for the determination of piroxicam by the enhancement of the tris‐(4,7‐diphenyl‐1,10‐phenanthrolinedisulphonic acid) ruthenium(II) (RuBPS)–cerium(IV) system and its application

A simple, rapid chemiluminescence (CL) method was described for the determination of piroxicam, a commonly used analgesic agent drug. A strong CL signal was detected when cerium(IV) sulphate was injected into tris‐(4,7‐diphenyl‐1,10‐phenanthrolinedisulphonic acid) ruthenium(II) (RuBPS)–piroxicam solution. The CL signal was proportional to the concentration of piroxicam in the range 2.8 × 10^–8–1.2 × 10^–5 mol/L. The detection limit was 2 × 10^–8 mol/L and the relative standard deviation (RSD) was 3.7% (c = 7.0 × 10^–7 mol/L piroxicam; n = 11). The proposed method was applied to the determination of piroxicam in pharmaceutical preparations in capsules, spiked serum and urine samples with satisfactory results. Copyright © 2008 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence of the luminol–potassium periodate system enhanced by TGA–capped CdTe quantum dots for the determination of theophylline

The chemiluminescence (CL) behaviour of the luminol–potassium periodate system enhanced by CdTe quantum dots capped with thioglycolic acid (TGA–CdTe QDs) was studied using kinetic experiments, CL spectra, UV–vis absorption spectra and fluorescence spectra. The production of oxygen‐containing reactant intermediates (O₂^?? and OH^?) in the present CL system was verified by CL. The possible CL mechanism was discussed in detail. Furthermore, theophylline (THP) was determined based on its enhancement of the CL intensity of the CdTe QDs–luminol–potassium periodate system coupled with a flow‐injection technique. Under these optimized conditions, the linear range was found to be from 1.0 × 10^?8 to 1.0 × 10^?5 g/mL with a detection limit of 2.8 × 10^?9 g/mL (3σ). The recoveries for the determination of THP in tablets were from 98.2 to 99.6%.     

Light emission from the Fe2+–EDTA–ascorbic acid–H2O2 system strongly enhanced by plant phenolic acids

Oxidative reactions can result in the formation of electronically excited species that undergo radiative decay depending on electronic transition from the excited state to the ground state with subsequent ultra‐weak photon emission (UPE). We investigated the UPE from the Fe²⁺–EDTA (ethylenediaminetetraacetic acid)–AA (ascorbic acid)–H₂O₂ (hydrogen peroxide) system with a multitube luminometer (Peltier‐cooled photon counter, spectral range 380–630 nm). The UPE, of 92.6 μmol/L Fe²⁺, 185.2 μmol/L EDTA, 472 μmol/L AA, 2.6 mmol/L H₂O₂, reached 1217 ± 118 relative light units during 2 min measurement and was about two times higher (P < 0.001) than the UPE of incomplete systems (Fe²⁺–AA–H₂O₂, Fe²⁺–EDTA–H₂O₂, AA–H₂O₂) and medium alone. Substitution of Fe²⁺ with Cr²⁺, Co²⁺, Mn²⁺ or Cu²⁺ as well as of EDTA with EGTA (ethylene glycol‐bis(β‐aminoethyl ether)‐N,N,N′,N′‐tetraacetic acid) or citrate powerfully inhibited UPE. Experiments with scavengers of reactive oxygen species (dimethyl sulfoxide, mannitol, sodium azide, superoxide dismutase) revealed the dependence of UPE only on hydroxyl radicals. Dimethyl sulfoxide at the concentration of 0.74 mmol/L inhibited UPE by 79 ± 4%. Plant phenolics (ferulic, chlorogenic and caffec acids) at the concentration of 870 μmol/L strongly enhanced UPE by 5‐, 13.9‐ and 46.8‐times (P < 0.001), respectively. It is suggested that augmentation of UPE from Fe²⁺–EDTA–AA–H₂O₂ system can be applied for detection of these phytochemicals.     

Micellar effect on the photophysics of heteroleptic ruthenium(II)–phenanthrolinedisulfonato complexes

Luminescent heteroleptic ruthenium(II) complexes of type RuL_nX_3–n [L = 1,10‐phenanthroline (phen), X = 4,7 diphenyl phenanthroline disulfonate, (dpsphen) n = 0,1,2,3] were synthesized and their photophysical properties investigated in homogeneous and cationic (CTAB), anionic (SDS) and nonionic (Triton X‐100) micelles. The luminescent quantum yield and lifetime of the complexes were found to increase in the presence of micellar media and on the introduction of a disulfonate ligand into the coordination sphere. Both electrostatic and hydrophobic interactions play an important role in the micellar media. Thus, by changing the nature of the ligands and the medium, we were able to tune the photophysical properties of Ru(II) complexes. Copyright © 2015 John Wiley & Sons, Ltd.