Relative CL Intensity Research Articles

Potassium Bromate–quinine Chemiluminescence Detection of Thiram in Water Samples using Flow Injection Analysis

A flow injection-chemiluminescence (FI-CL) method is devised for the determination of thiram in natural water samples. The CL intensity is enhanced when thiram is oxidized with potassium bromate under strong acidic conditions subsequently using quinine as a sensitizer. Under the optimum experimental conditions the relative CL intensity was proportional to the concentration of thiram in the range from 0.001 to 20 mg/L with the limit of detection (S/N = 3) 6 × 10–4 mg/L and the throughput of injections of 200 samples/h. The coefficient of determination (R2), relative standard deviation (n = 4) and regression equation over the studied range were 0.9998 (n = 11), 0.94–1.76% and y = 873.9x – 41.1 (y corresponds to the CL intensity, mV, and x is the concentration of thiram, mg/L), respectively. The proposed method was applied for the determination of thiram in spiked natural water samples and results obtained were in good agreement with the previously reported HPLC method. A brief discussion on the possible CL reaction mechanism between thiram and potassium bromate enhanced by quinine has been described.

Self-enzyme chemiluminescence immunoassay capable of rapidly diagnosing the infection of influenza A (H1N1) virus

A highly sensitive self-enzyme immunoassay with 1,1′-oxalyldiimidazole chemiluminescence (ODI-CL) detection was developed for the first time to quantify influenza A (H1N1) virus. A specific capture antibody, capable of capturing hemagglutinin (HA) subtypes of H1N1, was immobilized on the surface of the magnetic Au-Fe3O4 nanocomposite. Neuraminidase (NA) subtype of H1N1 was acts as an enzyme in the self-enzyme immunoassay. A sample mixed with HA antibodies immobilized on the surface of magnetic Au-Fe3O4 nanocomposites was incubated for 1 h at 37 °C. After the incubation, magnetic Au-Fe3O4 nanocomposites separated with a magnetic bar were washed 3 times using phosphate buffered saline with Tween-20 (PBST). Then, 4-Methylumbelliferyl-N-acetyl-α-D-neuraminic acid (MUNANA), a fluorogenic substrate of NA, was added and incubated for 10 min to produce 4-Methylumbelliferone (4-MU) from the enzyme reaction between MUNANA and NA of H1N1. After the incubation, the solution containing 4-MU emitted bright light with the addition of ODI-CL reagents (e.g., H2O2 and ODI). The relative CL intensity of 4-MU was proportionally enhanced with the increase of H1N1. Also, the brightness and color of 4-MU light emitted from the self-enzyme immunoassay was dependent on pH. The self-enzyme immunoassay was able to analyze trace levels of influenza A (H1N1) virus with good accuracy, precision, reproducibility and excellent selectivity. The limit of detection (LOD = 3σ/slope) was as low as 0.19 U/ml. We expect that the self-enzyme immunoassay can be applied as a cost-effective and rapid method capable of selectively quantifying a specific influenza A virus such as H1N1, H3N2, and H5N1.

A chemiluminescence reagent free method for the determination of captopril in medicine and urine samples by using trivalent silver

A novel flow-injection chemiluminescence (FI-CL) method free of CL reagent was developed for the determination of captopril based on its enhancing effect on the CL derived from diperiodatoargentate(III)-sulfuric acid system. Compared with the conventional CL system, the CL system based on trivalent silver was characterized of good selectivity for the absence of CL reagent. The CL mechanism was discussed through CL spectra and UV–vis absorption spectra. The conditions of the FI-CL system were investigated and optimized. Under the optimal conditions, the relative CL intensity was linear with the captopril concentration in the range of 0.3–15.0μg/mL. The detection limit for captopril was 0.05μg/mL, and the relative standard deviation (n=11) was 2.0% for 5.0μg/mL captopril. The proposed method was applied to the analysis of captopril in tablet and human urine with the recoveries of 83.1%–112.5%, and the relative standard deviations of 0.5%–4.4%. The results obtained by the proposed method agreed well with those obtained from HPLC method. The proposed method is fast, convenient, and cost-effective for the determination of captopril in medicine and biological samples.

Co-metal-organic-frameworks with pure uniform crystal morphology prepared via Co2 + exchange-mediated transformation from Zn-metallogels for luminol catalysed chemiluminescence

Cation exchange-mediated transformation from Zn-metallogels (MOGs), which was a mild facile strategy relative to the demanding hydrothermal method, was employed to develop Co2+ metal-organic frameworks (Co-MOFs) at room temperature. The obtained Co-MOFs was of uniform octahedral morphology and possessed high activity to catalyze luminol chemiluminescence without extra oxidants. By adding cysteine, the CL emission of luminol-Co-MOFs system was further enhanced. Based on this phenomenon, Co-MOFs was utilized to build a practical sensing platform for cysteine determination. Under the optimized conditions, the relative CL intensity (ΔI) was proportional to the concentration of cysteine in the range of 2–10μM, and the detection limit was 0.49μM (3S/N). Moreover, the established method was applied to the determination of cysteine in commercially available pharmaceutical injections.

All-in-one dual-aptasensor capable of rapidly quantifying carcinoembryonic antigen

Using a dual DNA aptamer (CEA aptamer linked to hemin aptamer), capable of rapidly capturing carcinoembryonic antigen (CEA) and hemin, an all-in-one dual-aptasensor with 1,1′-oxalyldiimidazole (ODI) chemiluminescence detection was developed for the early diagnosis of human cancer. CEA and hemin competitively bound with the dual DNA aptamer while the mixture in a detection cell was incubated for 30min at room temperature. When Amplex Red and H2O2 were added in the detection cell after the incubation, the yield of resorufin formed from the reaction Amplex Red and H2O2 depended on the concentration of HRP-mimicking G-quardruplex DNAzyme formed from the binding interaction between hemin and the dual DNA aptamer. Bright red light was observed with the addition of ODI and H2O2 in the detection cell containing resorufin. Relative CL intensity of all-in-one dual-aptasensor, operated with the competitive reaction of CEA and hemin in the presence of the dual aptamer, was exponentially decreased with the increase of CEA concentration in human serum. The limit of detection (LOD=3σ) of the all-in-one dual-aptasensor which operated with excellent accuracy, precision, and reproducibility was as low as 0.58ng/ml. The good correlation between the easy to use all-in-one dual-aptasensor and conventional enzyme-linked immunosorbent assay (ELISA), operated with time consuming procedures (e.g., long incubations and multiple washings), indicates that the rapid all-in-one dual-aptasensor can be applied as a novel clinical tool for the early diagnosis of breast cancer.

Flow-based determination of methionine in pharmaceutical formulations exploiting TGA-capped CdTe quantum dots for enhancing the luminol-KIO4 chemiluminescence

A novel flow-injection chemiluminescence method (FI-CL) was established for the determination of methionine in this paper, based on its strong enhancement on CL intensity of the luminol-KIO4 system catalyzed by thioglycolic acid-capped CdTe quantum dots in alkaline media. Under the optimized conditions, the relative CL intensity was in proportion to methionine concentration in the range from 1.0×10−8 to 1.0×10−5gmL−1 with a detection limit of 6.6×10−9gmL−1 (3σ). The relative standard deviation (RSD) of the CL intensity for 1.0×10−6gmL−1 standard methionine solution was 0.97% (n=11). The proposed method was successfully applied to determine methionine in commercial pharmaceutical formulations with recoveries between 98.0% and 101.9%. The possible CL mechanism was discussed as well.

Determination of Montelukast in Plasma Using β-Cyclodextrins Coated on CoFe2O4 Magnetic Nanoparticles in Luminol-H2O2 Chemiluminescence System Optimized by Doehlert Design.

A novel chemiluminescence method using β-cyclodextrins coated on CoFe2O4 magnetic nanoparticles is proposed for the chemiluminometric determination of montelukast in plasma. The effect of coated β-cyclodexterinon CoFe2O4 magnetic nanoparticles in the chemiluminescence of luminol-H2O2 system was investigated. It was found that β-cyclodexterin coated on CoFe2O4 magnetic nanoparticles could greatly enhance the chemiluminescence of the luminol-H2O2 system. Doehlert design was applied in order to optimize the number of experiments to be carried out to ascertain the possible interactions between the parameters and their effects on the chemiluminescence emission intensity. This design was selected because the levels of each variable may vary in a very efficient way with few experiments. Doehlert design and response surface methodology have been employed for optimization pH and concentrations of the components. Results showed under the optimized experimental conditions, the relative CL intensity (ΔI) is increased linearly in the concentration range of 0.003-0.586 μgml(-1) of montelukast with limit of detection (LOD) 1.09×10(-4) μgml(-1) at S/N ratio of 3, limit of quantitative (LOQ) 3.59×10(-4) μgml(-1) and the relative standard deviation 2.63%. The method has been successfully applied to the determination of montelukast in plasma of human body. Results specified that relative chemiluminescence intensity (ΔI) has good proportional with the montelukast concentration with R(2)=0.99979. The test of the recovery efficiency for known amounts of montelukast was also performed, the recoveries range obtained from 98.2 to 103.3%, with RSDs of <4% indicated that the proposed method was reliable.

Chemiluminescence detection of hydroquinone with flow-injection analysis of luminol-hydrogen peroxide system catalyzed by Jacobsen's catalyst

In this research, an ultrasensitive, rapid and novel flow injection chemiluminescence (FI-CL) strategy has been validated for the determination of hydroquinone (HQ). It was found that the CL intensity of the luminol-hydrogen peroxide system could be enhanced sharply by Jacobsen's catalyst in alkaline solution and the joining of HQ was found to restrain the CL signal of the luminol-hydrogen peroxide reaction catalyzed by the Jacobsen's catalyst, which made it possible for the determination of HQ. Possible mechanism and series of instrumental and chemical arguments were discussed in detail. Under the selected experimental conditions, the relative CL intensity was linear with the concentration of HQ ranging from 6.0×10−10 to 1.0×10−8g/mL. The detection limit, at the signal-to-noise ratio of 3 (3σ), was 1.0×10−10g/mL. The relative standard deviation (RSD) for 2.0×10−9g/mL HQ was 2.7% (n=11). The presented CL methodology has been applied for the determination of HQ in water samples with satisfactory results.

Determination of doxorubicin in pharmaceutical preparation and rat plasma with luminol-K3Fe(CN)6 chemiluminescence system

A novel and rapid flow injection chemiluminescence (FI-CL) method was established for the determination of doxorubicin, which was based on the phenomenon that CL intensity of the reaction between K3Fe(CN)6 and luminol in alkaline solution could be strongly enhanced by doxorubicin. Under optimum conditions, the relative CL intensity of the system was linear with the concentration of doxorubicin in the range from 2.0 × 10−9 g/mL to 5.0 × 10−7 g/mL with a correlation coefficient of 0.9993 (n = 9). The detection limit (3σ) was 4.25 × 10−10 g/mL, and the relative standard deviation (RSD) for 1.0 × 10−7 g/mL doxorubicin (n = 11) was 0.33%. The method was applied to the determination of doxorubicin in pharmaceutical preparation and rat plasma, and the percentage recovery of doxorubicin in rat plasma was between 89.8% and 102.2%. The possible CL mechanism was also discussed briefly.

A novel flow injection chemiluminescence method for the determination of ractopamine in urine by using trivalent copper

In this paper, a novel chemiluminescence method was proposed for the determination of ractopamine by combining with flow injection technology. The chemiluminescence system was based on oxidation of luminol by diperiodatocuprate(III) in the presence of ractopamine. The diperiodatocuprate(III) was obtained by complexation of copper in the trivalent oxidation state with periodate in a strong alkaline medium. Hereby under the optimum conditions, the relative CL intensity was proportional to the concentration of ractopamine over the range 1.0 × 10−9 g mL−1 to 1.0 × 10−6 g mL−1, with a limit of detection (3σ) of 3.4 × 10−10 g mL−1. The relative standard deviation (R.S.D.) was 2.1% for 5.0 × 10−8 g mL−1 ractopamine (n = 7). The sensitive method was successfully applied for the determination of ractopamine (ng mL−1) in urine samples. The possible mechanism of the CL reactions was also discussed.

Sensitive chemiluminescence determination of phentolamine mesylate and phenoxybenzamine hydrochloride based on K3Fe(CN)6–H2O2–fluorescein

A new, rapid and sensitive flow-injection chemiluminescence (FI-CL) method was developed and validated for the determination of two alpha (α)-adrenoreceptor blockers: phentolamine mesylate (PM) and phenoxybenzamine hydrochloride (PH). The method was based on the finding that K3Fe(CN)6 and H2O2 could oxidize fluorescein in an alkaline medium to produce a CL signal, and the joining of PM or PH could enhance the CL intensity significantly. A series of chemical and instrumental parameters affecting the CL response was investigated. Under the optimum conditions, the relative CL intensity was proportional to the concentration of sample solutions in the range 3×10−8 to 1×10−6g/mL for PM and 5×10−8 to 5×10−6g/mL for PH. The detection limits were 0.53ng/mL for PM (r2=0.9947) and 2.60ng/mL for PH (r2=0.9791). For 11 repeated measurements of 1.0×10−6g/mL sample solutions, the relative standard deviations (RSDs) were <3.6%. The proposed method has been successfully applied to the analyses of PM and PH in injections and PH in tablets. A brief discussion on the possible CL reaction mechanism is presented.

Flow injection chemiluminescence determination of isoxicam based on diperiodatoargentate(III)-fluorescein system in a micellar medium

A novel and highly sensitive flow injection chemiluminescence (FI-CL) method has been developed for the assay of isoxicam. The method is based on the luminescence of the diperiodatoargentate(III)-fluorescein-isoxicam system, where fluorescein is used as an energy-transfer reagent in alkaline medium. The emission intensity is greatly enhanced by the presence of cetyltrimethylammonium bromide (CTAB). Optimum conditions and possible mechanisms have been investigated. The relative CL intensity is linear with the isoxicam concentration in the range of 3.0×10−10–1.0×10−6g/ml with a detection limit of 7.0×10−11g/ml (3σ). The relative standard deviation (RSD) is 1.7% at 1.0×10−8g/ml of isoxicam (n=11). The present CL procedure was successfully applied to the determination of isoxicam in pharmaceutical formulations and biological fluids.

One novel chemiluminescence sensor for determination of fenpropathrin based on molecularly imprinted porous hollow microspheres

In this paper, a novel chemiluminescence–molecular imprinting (CL–MI) sensor for determination of fenpropathrin in foodstuff has been developed. Fenpropathrin-imprinted porous hollow microspheres (FIPHMs) were prepared using mesoporous silica particles as cores. The mesoporous silica particles were modified by 3-Aminopropyltrimethoxysilane (APTS) and acrylyl chloride, respectively, and coated with a tunable thickness layer of template molecules and functional monomer by precipitation polymerization. The cores were finally dissolved to form the hollow structure of FIPHMs. The specific hollow structure made FIPHMs have highly dense of effective binding sites at both internal and external surfaces which enhanced its adsorption abilities and enrichment towards fenpropathrin molecule. The CL–MI flow sensor was built by packing the FIPHMs into a self-made polymethyl methacrylate flow cell. Tests showed that the prepared sensor achieved high sensitivity and selectivity. Under the optimal conditions, the relative CL intensity was linear with fenpropathrin concentration from 5.0×10−8 to 1.5×10−5gmL−1 and with a detection limit of 3.07×10−8gmL−1. The novel sensor has been successfully applied to the determination of fenpropathrin in food samples.

Biomimetic enhanced chemiluminescence of luminol–H2O2 system by manganese (III) deuteroporphyrin and its application in flow injection determination of phenol at trace level

Abstract A novel, sensitive and high selective flow-injection chemiluminescence (FI-CL) method for the determination of phenol is reported, based upon its decreasing effect on the CL reaction of luminol with hydrogen peroxide catalyzed by manganese (III) deuteroporphyrin [MnDP, Scheme 1 , 3] in alkaline solution. Under the selected optimized experimental conditions, the relative CL intensity was linear with phenol in the range of 4.0 × 10−9 to 4.0 × 10−7 g mL−1. The detection limit (3σ) was 6.3 × 10−10 g mL−1 and the relative standard deviation for 1.0 × 10−7 g mL−1 phenol (n = 11) was 2.99%. The regression equation was I = 120.79 + 1.14 × 1010c (R = 0.9936). This method has been applied to the determination of phenol in water with satisfactory results.

Rapid monitoring of alkaline phosphatase in raw milk using chemiluminescence detection.

A simple biosensor with 1,1'-oxalyldiimidazole chemiluminescence (ODI-CL) detection capable of rapidly quantifying and screening alkaline phosphatase (ALP) in raw and pasteurized milk was developed as an indicator for confirming whether commercial milk is properly pasteurized. Fluorescein was formed when standards containing 1.0% milk with different activities of ALP and samples containing 1.0% raw milk were incubated with fluorescein diphosphate (FDP) for 15 min at room temperature. The relative CL intensity of fluorescein measured with the addition of 80 mM H2O2 and ODI formed from the reaction of 2.0 μM bis(2,4,6-trichlorophenyl) oxalate and 10.0 μM 4-methyl imidazole in ethyl acetate was proportional to the concentration of ALP in milk. The range (39∼2500 mU/L) of linear calibration curve (R2 = 0.998) for the quantification of ALP in milk using ODI-CL detection was wider than those using currently applied fluorescence and 1,2-dioxetane CL detections. Also, the limit of detection (3.7 mU/L) determined using the former detection, which has good precision, was lower than those reported using the latter detections. In conclusion, the cost-effective and highly sensitive biosensor with ODI-CL detection can be applied to monitor whether milk is pasteurized according to acceptable ALP activities threshold level (350 mU/L) for public safety newly adopted by US and EU and the internal investigation level (100 mU/L) proposed by EU.

Enhancement of peroxyoxalate chemiluminescence intensity by surfactants and its application to detect detergent

Enhancement of peroxyoxalate chemiluminescence (PO-CL) intensity by a surfactant in the H(2)O(2)/bis(2,4,6-trichlorophenyl)oxalate (TCPO)/rhodamine B system was described. The effects of 15 surfactants were evaluated by comparing the ratio of a relative CL intensity (RCI) with surfactant to that of the blank in each system. In preliminary study, H(2)O(2)/imidazole-HNO(3) buffer/TCPO/rhodamine B system was used to study the effects of surfactants on PO-CL intensity. Fourteen surfactants reduced the CL intensity at the 2% concentration, where their relative CL intensities ranged from 0.6 to 93.5%. Some of these phenomena may be caused by a notable change of pH that was occurred by adding the surfactant. Additionally, enhancement of PO-CL intensity was studied by using system (1) H(2)O(2)/TCPO/rhodamine B and (2) H(2)O(2)/imidazole-HNO(3) buffer/TCPO/systems. In the system 1, the favorable enhancement of CL intensity (ranged from 124 to 472%) was observed with 9 surfactants at the 0.5% concentration. This result suggested that several surfactants might play a role as a catalyst in the PO-CL reaction. There was no tendency to enhance CL intensity among the surfactant types. In the system 2, the enhancement of CL intensity was also observed by adding with 11 surfactants, which might be mainly caused by the fluorescent impurities of surfactants used. Furthermore, detection of detergent commercially available was applied by using the system 1.

A novel flow-injection chemiluminescence determination of uric acid based on diperiodatoargentate(III) oxidation

A novel and high selectivity flow-injection chemiluminescence (FI-CL) system with diperiodatoargentate(III) (DPA) is developed for the determination of uric acid for the first time. It is based on the reaction of diperiodatoargentate(III) (DPA) with uric acid in alkaline medium to emit CL. With the peak height as a quantitative parameter applying optimum working conditions, the relative CL intensity was linear with the uric acid concentration in the range of 4.0 x 10(-7)-2.0 x 10(-4) mol L(-1) with a detection limit of 1.2 x 10(-7) mol L(-1) (3 sigma). The relative standard deviation (RSD) was 2.1% for 5.0 x 10(-5) mol L(-1) uric acid (n=7). The proposed method held higher selectivity than other CL methods and was applied to determination of uric acid in human serum. The possible CL reaction mechanism was also discussed briefly.

Flow‐injection chemiluminescence determination of ofloxacin using the Ru(bpy)2(CIP)2+−Ce(IV) system and its application

This paper reports a flow-injection chemiluminescence method for the determination of ofloxacin (OFLX) using the Ru(bpy)2(CIP)2+-Ce(IV) system. Under the optimum conditions, the relative CL intensity was proportional to the concentration of OFLX in the range 3.0 x 10(-8)-1.0 x 10(-5) mol/L and the detection limit was 4.2 x 10(-9) mol/L. The proposed method has been successfully applied to the determination of ofloxacin in pharmaceuticals and human urine. The chemiluminescence mechanism of the system is also discussed.

Determination of tsumacide residues in vegetable samples using a flow‐injection chemiluminescence method

A sensitive, simple and rapid flow-injection chemiluminescence (FI-CL) method is described to determine tsumacide pesticide residue based on the CL reaction of the alkaline degradation product of tsumacide with acidic KMnO(4) when rhodamine 6G was present. Under the optimum conditions, the relative CL intensity is linear with the concentration of tsumacide in the range of 2.0 x 10(-3)-0.20 mg/L. The detection limit is 6.6 x 10(-4) mg/L (3sigma) and the relative standard deviation for 2.0 x 10(-2) mg/L tsumacide solution was 2.28% (intra-day) and 4.85% (inter-day). The proposed method has been applied to determine the residue of tsumacide in vegetable samples and the recovery test is very satisfactory.