luminol-H2O2 Chemiluminescence Reaction Research Articles

Two-dimensional metal-organic framework catalyzed chemiluminescent reaction for alpha-glucosidase inhibitor screening

α-Glucosidase inhibitors (AGIs) are oral antidiabetic drugs used in the treatment of type Ⅱ diabetes. It is integral to establish methods for AGIs screening. For the detection of α-glucosidase (α-Glu) activity and screening of AGIs, a chemiluminescence (CL) platform was established based on cascade enzymatic reactions. Firstly, the catalytic activity of a two-dimensional (2D) metal-organic framework (MOF) with iron as central metal atoms and 1,3,5-benzene tricarboxylic acid as a ligand (denoted as 2D Fe-BTC) in the luminol-hydrogen peroxide (H2O2) CL reaction were studied. Mechanism studies showed that the Fe-BTC may react with H2O2 to produce ·OH and act as catalase to facilitate the decomposition of H2O2 to produce O2, thus showing good catalytic activity in the luminol-H2O2 CL reaction. The proposed luminol–H2O2–Fe-BTC CL system exhibited an outstanding response to glucose with the aid of glucose oxidase (GOx). The luminol-GOx-Fe-BTC system showed a detection linear range from 50 nM to 10 μM with a detection limit (LOD) of 3.62 nM for glucose detection. Then, the luminol–H2O2–Fe-BTC CL system was applied to the detection of α-glucosidase (α-Glu) activity and screening of AGIs based on cascade enzymatic reactions using acarbose and voglibose as model drugs. The IC50 of acarbose and voglibose was 7.39 μM and 1.89 mM, respectively.

Atomic Dispersion of Zn2+ on N-Doped Carbon Materials: From Non-Activity to High Activity for Catalyzing Luminol-H2O2 Chemiluminescence.

Fe and Co single-atom catalysts (SACs) have been widely explored in many fields, while Zn SACs are still in their infancy stage. Herein, we unexpectedly found that atomically dispersed Zn2+ on N-doped carbon material (Zn-N-C) exhibited high catalytic activity on luminol-H2O2 chemiluminescence (CL) reaction. The Zn-N-C SACs were readily prepared through simple pyrolyzation of the cheap precursors (dopamine and ZnCl2). The mechanism of Zn SAC-catalyzed CL reaction of luminol-H2O2 was investigated in detail. The activity of Zn SACs originated from the Zn-N sites in the Zn-N-C structure. The monoatomic dispersion makes Zn2+ catalytic performance change from no activity to high activity in luminol-H2O2 CL reaction. This study demonstrated the particularity of the monatomic metal catalyst over the conventional metal ion. This work provides the unprecedented perspective for design of new metal SACs in CL reaction.

CoN4-supported Co2N metal clusters for developing sensitive chemiluminescent immunochromatographic assays

In view of the optimal catalytic efficiency (∼100%), single-atom site catalysts are being widely exploited in a range of areas including organic synthesis, energy conversion, environmental remediation, biotherapy, etc. However, low loading ratio of the unitary active sites on single-atom site catalysts dramatically hinders the remarkable improvement of their catalytic activity. Hereby, a facile low-temperature reduction protocol was adopted for synthesizing CoN4-supported Co2N metal clusters on graphitic carbon nitride, which show the remarkably superior chemiluminescent (CL) catalytic capacity than some reported pure single-atom site catalysts. Nitrogen-encapsulated Co2N clusters coupled with isolated Co–N4 moieties (Co2N@Co–N4) endowed the synergetic catalysts with high Co content of 53.2 wt%. Through X-ray absorption spectroscopy, the synergetic active sites (Co2N@Co–N4) afforded the CoN4-supported Co2N clusters with the remarkable catalytic activity for accelerating the decomposition of H2O2 to produce extensive superoxide radical anion rather than singlet oxygen or hydroxyl radical. Therefore, the CoN4-supported Co2N clusters possessed the superb enhancement effect on luminol-H2O2 CL reaction by ∼22829 times. The CoN4-supported Co2N clusters were utilized as signal probes to establish a CL immunochromatographic assay (ICA) platform for quantitating mycotoxins. Herein, aflatoxin B1 was employed as a mode analyte and the limit of detection was as low as 0.33 pg mL−1 (3σ). As a proof-of-principle work, the developed ICA protocol was successfully employed on the detection of aflatoxin B1 spiked in Angelica dahurica and Ganoderma lucidum with acceptable recoveries of 84.0–107.0%. The ideal practicability of the work elucidates that CoN4-supported Co2N clusters showed a new perspective for developing the sensitive CL biosensing.

Novel Chemiluminescence Sensor for Thrombin Detection Based on Dual-Aptamer Biorecognition and Mesoporous Silica Encapsulated with Iron Porphyrin.

Thrombin is a marker of blood-related diseases, and its detection is of great significance in the fields of medical and biological research. Herein, a novel chemiluminescence (CL) sensor for thrombin detection was prepared based on dual-aptamer biorecognition and mesoporous silica encapsulated with iron porphyrin. Mesoporous silica encapsulated with hematin by aptamer1 (Apt1/hematin/M-SiO2) and magnetic microspheres modified with aptamer2 (Apt2/NH2-MS) were successfully prepared, and the two materials were used to construct a CL sensor to detect thrombin. Primarily, Apt2/NH2-MS is used for pretreatment separation of thrombin samples by the biorecognition effect between the aptamer (Apt2) and target (thrombin). Then, thrombin/Apt2/NH2-MS is again recognized with Apt1 on the surface of Apt1/hematin/M-SiO2 and Apt1/thrombin/Apt2/NH2-MS is formed, so dual-aptamer biorecognition is realized. Meanwhile, the generated Apt1/thrombin/Apt2/NH2-MS makes Apt1 shed off the surface of M-SiO2 and release hematin. The released hematin can catalyze the luminol-H2O2 CL reaction. Therefore, a sandwich-type CL sensor was constructed based on dual-aptamer biorecognition and hematin catalysis for the detection of thrombin. The sensor has a linear range of 7.5 × 10-15 to 2.5 × 10-10 mol·L-1 and a detection limit of 2.2 × 10-15 mol·L-1 and also exhibits excellent selectivity, reproducibility, and stability. The sensor was successfully used for the detection of thrombin in serum samples, which makes it possible to apply the sensor in the detection of thrombin in actual samples.

Luminol-reduced Au nanoparticles-based dual-signal immunochromatographic test strip for pesticide residues

Luminol-reduced Au nanoparticles (AuNPs) were prepared by using a facile one-step method. Luminol-reduced AuNPs were utilized as a novel dual-readout probe to develop a qualitative/quantitative immunochromatographic test strip (ITS) for detecting pesticide residues, by adopting fenvalerate as a model analyte. Fenvalerate in sample solution could compete with its corresponding immobilized coating antigen in test line of ITS to bind the AuNPs-tagged fenvalerate monoclonal antibody. After the complete immunoreaction, the AuNPs-tagged antibody in test line was the dual-readout probe. Superior to signal readout-based ITSs, especially traditional Au nanoparticles-based ITSs, luminol-reduced AuNPs-based dual-readout ITSs could simultaneously meet the demand of qualitative analysis and quantitative detection. Colorimetric signal from luminol-reduced AuNPs could be adopted as a qualitative readout, which could increase analysis efficiency in field analysis and rapid testing. In the proposed analytical platform, fenvalerate could be semi-quantitated within 15 min. Furthermore, as for affirmed contaminated sample through colorimetric analysis, chemiluminescent (CL) signal originating from luminophor-modified AuNPs as a quantitative readout aided to improve analytical sensitivity after triggering luminol-H2O2 CL reaction. Under the optimal conditions, the detection limit for fenvalerate were 0.067 ng/mL (S/N = 3). The reliability of dual-readout ITSs was demonstrated through the successful practical application on traditional Chinese medicines. Owing to high analysis efficiency, low cost, high facility and improved accuracy, the dual-readout ITSs by using only one probe showed great potential in field analysis and rapid testing for drug safety, environmental sanitation and clinical diagnosis.

Improvement of mimetic peroxidase activity of gold nanoclusters on the luminol chemiluminescence reaction by surface modification with ethanediamine.

Peroxidase is a commonly used catalyst in luminol-H2 O2 chemiluminescence (CL) reactions. Natural peroxidase has a sophisticated separation process, short shelf life and unstable activity, therefore it is important to develop peroxidases that have both high catalytic activity and good stability as alternatives to the natural enzyme. Gold nanoclusters (Au NCs) are an alternative peroxidase with catalytic activity in the luminol-H2 O2 CL reaction. In the present study, ethanediamine was modified on the surface of Au NCs forming cationic Au NCs. The zeta potential of the cationic Au NCs maintained its positive charge when the pH of the solution was between 4 and 9. The cationic Au NCs showed higher catalytic activity in the luminol-H2 O2 CL reaction than did unmodified Au NCs. A mechanism study showed that the better performance of cationic Au NCs may be attributed to the generation of 1 O2 on the surface of cationic Au NCs and a positive surface charge, for better affinity to luminol. Cationic Au NC, acting as a peroxidase mimic, has much better stability than horseradish peroxidase over a wide range of temperatures. We believe that cationic Au NCs may be useful as an artificial peroxidase for a wide range of potential applications in CL and bioanalysis.

Colorimetric/chemiluminescent immunochromatographic test strip by using luminol-reduced gold nanoparticles as dual-response probes

Luminol-reduced gold nanoparticles (LuReGNPs) were prepared and utilized as dual-response signal probes for the development of a colorimetric/chemiluminescent immunochromatographic test strip (ITS). LuReGNPs-labeled antibody was adopted as the signal tracer to conduct immunoassay of mouse IgG using the developed ITS device. After 6-min competitive immunoreaction, the tracer antibody was captured on the test zone, which led to accumulation of LuReGNPs. The appearance of red color resulting from LuReGNPs accumulation on the test zone was observed by naked eyes as a qualitative and semi-quantitative signal. Moreover, luminophore in the signal probes enabled sensitive quantitation after initiating the luminol-H2O2 chemiluminescent reaction. Under the optimal conditions, mouse IgG was detected within a linear range of 0.10–100 ng/mL with a detection limit of 0.033 ng/mL (S/N = 3). The results for real biological samples detection and recovery tests demonstrated the acceptable reliability of the dual-response ITS. It exhibited great potential in both rapid screening and sensitive quantitation. Due to the merits of facile manipulation, short detection time and ideal portability, the platform could be further extended to multianalyte immunoassay of biomarker proteins for point-of-care test.

Enhancement effect of p-iodophenol on gold nanoparticle-catalyzed chemiluminescence and its applications in detection of thiols and guanidine

In the present study, the effects of nine compounds on the luminol-O2 chemiluminescence (CL) reaction catalyzed by gold nanoparticles (Au NPs) were investigated. p-Iodophenol (PIP), known as a traditional enhancer in horseradish peroxidase (HRP)-catalyzed luminol-H2O2 CL reaction, exhibited the highest enhancement effect on the luminol-O2-Au NPs CL reaction. The addition of PIP at a final concentration of 1.25 mM to luminol-O2-Au NPs CL system enhanced the CL signal almost 30-fold. Interestingly, the enhanced CL reaction exhibited a slow and intense CL signal which is different from the CL profile of luminol-H2O2-Au NPs CL system reported in previously. The experimental conditions of the PIP enhanced luminol-O2-Au NPs CL system were investigated systematically in the present study. And the mechanism studies showed that superoxide anion (O2•-) and singlet oxygen (1O2) generated from dissolved oxygen played an important role during the CL reaction. Furthermore, the effects of some organic compounds on the enhanced CL system were investigated. The results showed that compounds containing -SH and guanidine group can inhibit the signal of the enhanced CL reaction indicating the applicability of the proposed CL reaction for the detection of such compounds.

Catalyst metal ions and luminol bifunctionalized gold nanoparticles: Unique chemiluminescence property for Cu(II) monitoring

Abstract In this work, catalyst metal complexes and luminol bifunctionalized AuNPs by virtue of cysteine as bridge molecule (M/cysteine-luminol-AuNPs), and catalyst metal ions and luminol directly bifunctionalized AuNPs (MI-luminol-AuNPs) by virtue of 3-aminophthalate anion as in situ chelators were prepared for the first time. Particularly, MI-luminol-AuNPs prepared with Co(II) and Cu(II) exhibited highly enhanced chemiluminescence (CL) activities. The greatly enhanced CL activities were attributed to the synergetic catalytic effect of metal ions and AuNPs on luminol-H2O2 CL reaction. Interestingly, special two peak CL emission was observed with Cu(II) and luminol directly bifunctionalized AuNPs (Cu(II)-luminol-AuNPs) reacted with H2O2. Thus, a simple CL sensing strategy was developed for Cu(II) monitoring by virtue of Cu(II) regulated on-site assembly of Cu(II)-luminol-AuNPs. The linear detection range was from 20 to 800 μM, and the limit of detection was 5.0 μM. Finally, the proposed detection method was successfully applied to the determination of Cu(II) ions in real spiked water samples.

Simultaneous and Sensitive Determination of Levodopa and Carbidopa in Pharmaceutical Formulation and Human Serum by High Performance Liquid Chromatography with On-Line Gold Nanoparticles-Catalyzed Luminol Chemiluminescence Detection

Abstract Levodopa, the metabolic precursor of dopamine, is usually administrated in combination with carbidopa to control dopamine levels in an appropriate manner and reduce side effects in the treatment of Parkinson's disease. In this study, a selective and sensitive high performance liquid chromatography coupled with on-line gold nanoparticles-catalyzed luminol chemiluminescence method for simultaneous determination of levodopa and carbidopa was developed. This method was based on the strongly enhanced chemiluminescence signal of on-line gold nanoparticles-catalyzed luminol-H2O2 system by levodopa and carbidopa. The possible enhancement mechanism was attributed to that levodopa and carbidopa could promote the on-line formation of a large number of gold nanoparticles, which catalyzed the luminol-H2O2 chemiluminescence reaction. The good separation of levodopa and carbidopa was achieved with isocratic elution using a mixture of methanol and 0.2% aqueous phosphoric acid (5:95, V/V) within 10.5 min. Under the optimal conditions, the linear ranges of levodopa and carbidopa were 2.24–448 ng mL−1 and 4.32–1080 ng mL− with the detection limits of 0.89 and 1.08 ng mL− (S/N = 3), corresponding to 17.92 and 21.60 pg for 20 μL sample injection, respectively. The validated method was successfully applied to simultaneous quantification of levodopa and carbidopa in controlled-release tablets (Sinemet®) and human plasma. The average recoveries of levodopa and carbidopa in the tablets were 100.5% and 103.1% with the precisions (RSDs) of 2.4% and 4.0%. The recoveries of levodopa and carbidopa in human plasma ranged from 97.0% to 103.5% with RSDs of no more than 3.3%.

Chemiluminescence of off-line and on-line gold nanoparticle-catalyzed luminol system in the presence of flavonoid.

It was found that flavonoids could remarkably inhibit the chemiluminescence (CL) intensity of an off-line gold nanoparticle (AuNP)-catalyzed luminol-H2 O2 CL system. By contrast, flavonoids enhanced the CL intensity of an on-line AuNP-catalyzed luminol-H2 O2 CL system. In the off-line system, the AuNPs were prepared beforehand, whereas in the on-line system, AuNPs were produced by on-line mixing of luminol prepared in a buffer solution of NaHCO3 -Na2 CO3 and HAuCl4 with no need for the preliminary preparation of AuNPs. The on-line system had prominent advantages over the off-line system, namely a lowering of the background noise and improvements in the stability of the CL system. The results show that differences in the signal suppression effect of flavonoids on the off-line AuNP-catalyzed CL system are influenced by the combined action of a free radical scavenging effect and occupy-sites function; the latter was proved to be predominant using controlled experiments. Enhancement of the on-line system was ascribed to the presence of flavonoids promoting the on-line formation of AuNPs, which better catalyzed the luminol-H2 O2 CL reaction, and the enhancement activity of the six flavonoids increased with the increase in reducibility. This work broadens the scope of practical applications of an AuNP-catalyzed CL system.

An ultra-facile and label-free immunoassay strategy for detection of copper (II) utilizing chemiluminescence self-enhancement of Cu (II)-ethylenediaminetetraacetate chelate

The establishment of facile, rapid, sensitive and cost-effective protocols for the detection of heavy metals is of great significance for human health and environmental monitoring. Hereby, an ultra-facile and label-free immunoassay strategy was designed for detecting heavy metal ion by using Cu (II) as the model analyte. Cu (II) reacted previously with ethylenediaminetetraacetate (EDTA) was captured by immobilized monoclonal antibody for Cu (II)-EDTA chelate. Then Cu (II) was detected based on the self-enhancing effect of Cu (II)-EDTA chelate to luminol-H2O2 chemiluminescence reaction. The CL intensity is linear relative with Cu (II) concentration in a very wide range of 1.0–1000ng/mL, with a detection limit of 0.33ng/mL (S/N=3). Since the specificity of this proposed strategy relied on both the specificity of monoclonal antibody and the specificity of luminol-H2O2 system, it could avoid interference from most common ions. The proposed method was used successfully to detect Cu (II) in traditional Chinese medicine and environmental water samples with acceptable recovery values of 82–113%. This proof-of-principle work demonstrated the feasibility of the label-free immunoassay for heavy metal ions, and opened a new avenue for rapid screening and field assay for drug safety, environmental monitoring and clinical diagnosis.

Graphene–copper oxide nanocomposite with intrinsic peroxidase activity for enhancement of chemiluminescence signals and its application for detection of Bisphenol-A

Graphene–copper(II) oxide (G–CuO) nanocomposite was synthesized for the first time by simple and rapid microwave assisted co-precipitation method using copper acetate as a precursor. Synthesized G–CuO nanocomposite showed the characteristic Raman and Fourier transform infrared peaks of CuO below 700cm−1. Characteristic crystalline peaks of CuO corresponding to monoclinic symmetry was observed in X-ray diffraction analysis. Nanocomposite with quasi-spherical morphology was observed in transmission electron microscopic analysis. Nanocatalytic activity of G–CuO nanocomposite was examined by its efficiency to improve the signals of luminol–H2O2 chemiluminescence (CL) reaction. G–CuO nanocomposite enhanced the signals of CL reaction by 280 times higher than control. Enhancement in CL signals is attributed to intrinsic peroxidase like activity of G–CuO nanocomposite on H2O2 breakdown to OH− and O2 ions. Formation of radicals and ions by nanocatalytic mechanism was hypothesized and confirmed by trolox assay. G–CuO has higher intrinsic peroxidase like activity than bare copper oxide (CuO) nanoparticles by 23 times. G–CuO nanocomposite can be a better alternative to peroxidases and nanomaterials which are used to enhance the CL signals. Analytical application of enhanced luminol–H2O2 CL reaction was applied for detection of Bisphenol-A (BPA) in feeding bottles and polycarbonate water bottles. Proposed enhanced CL method has linearity in the range 10,000–1ng/mL with limit of detection of 0.55ng/mL and limit of quantification of 8.3ng/mL. Intrinsic peroxidase like activity of synthesized G–CuO can have wide application in nanocatalysis and analytical chemistry for the development of CL based analytical and biomedical kits, sensors, and assays.

The development of a novel chemiluminescent glucose sensor using hydrophilic Co3O4@SiO2 mesoporous nanoparticles

The development of a novel chemiluminescent glucose sensor using hydrophilic Co3O4@SiO2 mesoporous nanoparticles.

Sensitive and rapid chemiluminescence detection of propranolol based on effect of surface charge of gold nanoparticles

We report a label-free, gold nanoparticles (AuNPs)-based chemiluminescent method for propranolol assay. The method relies upon the catalytic activity of unmodified AuNPs on the luminol–H2O2 chemiluminescence (CL) reaction, and the interaction of unmodified AuNPs with propranolol. The surface charge property of AuNPs directly affects their catalytic performance for CL reaction, and the interaction of AuNPs with propranolol can change AuNPs׳ surface charge property and induce the AuNP aggregation, and after aggregation the catalytic activity of AuNPs on the luminol–H2O2 CL reaction is greatly enhanced. During the assay, no covalent functionalization of AuNPs is required. The assay is homogenous. The detection limit of propranolol (3σ) was estimated to be as low as 6.6×10−12gmL−1, and the sensitivity was 4 orders of magnitude better than that of known CL methods for the detection of propranolol. This AuNPs-based CL method offers the advantages of being simple, cheap, rapid, and sensitive.

Simultaneous quantification of catecholamines in rat brain by high-performance liquid chromatography with on-line gold nanoparticle-catalyzed luminol chemiluminescence detection.

A new method based on high-performance liquid chromatography (HPLC) coupled with on-line gold nanoparticle-catalyzed luminol chemiluminescence (CL) detection was developed for the simultaneous quantitation of catecholamines in rat brain. In the present CL system, gold nanoparticles were produced by the on-line reaction of H2 O2 , NaHCO3 -Na2 CO3 (buffer solution of luminol) and HAuCl4. Norepinephrine (NE), epinephrine (EP) and dopamine (DA) could strongly enhance the CL signal of the on-line gold nanoparticle-catalyzed luminol system. The UV-visible absorption spectra and transmission electron microscopy studies were carried out, and the CL enhancement mechanism was proposed. Catecholamines promoted the on-line formation of more gold nanoparticles, which better catalyzed the luminol-H2 O2 CL reaction. The good separation of NE, EP and DA was achieved with isocratic elution using a mixture of methanol and 0.2% aqueous phosphoric acid (5:95, v/v) within 8.5 min. Under the optimized conditions, the detection limits, defined as a signal-to-noise ratio of 3, were in the range of 1.32-1.90 ng/mL, corresponding to 26.4-38.0 pg for 20 μL sample injection. The recoveries of catecholamines added to rat brain sample were >94.6%, with the precisions <5.5%. The validated HPLC-CL method was successfully applied to determine NE and DA in rat brain without prior sample purification.

One-step homogeneous non-stripping chemiluminescence metal immunoassay based on catalytic activity of gold nanoparticles

The catalytic activity of gold nanoparticles (AuNPs) on a luminol–H2O2 chemiluminescence (CL) system is found to be greatly enhanced after its crosslinking aggregation induced by immunoreaction. Based on this observation, a one-step homogeneous non-stripping CL metalloimmunoassay was designed. In the presence of corresponding antigen (Ag), the immunoreaction caused the aggregation of antibody (Ab)-modified AuNPs, and these crosslinking aggregated AuNPs could catalyze luminol–H2O2 CL reaction to produce a much stronger CL signal than dispersed Ab-modified AuNPs. The assay, including immunoreaction and detection, can be accomplished in homogeneous solution. In the assay, no tedious and strict stripping of metal nanoparticles, difficult synthesis of labels, multiple steps of immunoreactions and washings, and complicated magnetic separation process were required. The detection limit of human immunoglobulin G (IgG, 3σ) was estimated to be as low as 3.2×10−11gml−1. The sensitivity was increased by two orders of magnitude over that of other AuNP-based CL immunoassay. The current CL metalloimmunoassay offers the advantages of being simple, cheap, rapid, and sensitive.

Artificial Enzyme Mimics for Catalysis and Double Natural Enzyme Co-immobilization

This work presents a new chemiluminescent (CL) probe array assay. The new type CL probe array is based on enzyme mimics of Co3O4-SiO2 mesoporous nanocomposite material, which not only have an excellent catalytic effect on the luminol-H2O2 CL reaction in an alkaline medium but also can be used for the immobilization of enzymes. The linear range of the lactose concentration is 3.0 × 10(-7) to 1.0 × 10(-5) g mL(-1) and the detection limit is 6.9 × 10(-8) g mL(-1). β-Galactosidase and glucose oxidase were selected as a model for enzyme assays to demonstrate the applicability of Co3O4-SiO2 mesoporous nanocomposite material in multienzyme immobilization. The novel bifunctional CL probe array has been successfully applied to the determination of lactose in milk.

Determination of cysteine and glutathione based on the inhibition of the dinuclear Cu(II)-catalyzed luminol–H2O2 chemiluminescence reaction

The catalyzed luminol chemiluminescent reaction has received a great amount of attention because of its high sensitivity and low background signal which make the reaction an attractive analytical chemistry tool. The present study, introduces the beneficial catalytic effects of dinuclear Cu(II) complex [Cu2L2(TAE)]X2, where TAE=tetraacetylethane; L=N,N’-dibenzylethylenediamine and X=ClO4 on the luminol chemiluminescent reaction as a novel probe for the determination of glutathione (GSH) and L-cysteine (CySH) in human serum and urine. The [Cu2L2(TAE)]X2 has exhibited highly efficient catalytic activity of luminol CL as an artificial peroxidase model at pH as low as 7.5 in water in the presence of H2O2⋅GSH and CySH can induce a sharp decrease in CL intensity from the [Cu2L2(TAE)]X2-catalyzed luminol system. Under the selected experimental conditions, a linear relationship was obtained between the CL intensity and the concentrations of GSH and CySH in the range of 1.0×10−7–1.0×10−4M, with detection limits (S/N=3) of 2.7×10−8 and 6.8×10−8M and RSD<4.2% (n=7) for GSH and CySH, respectively.

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-H2 O2 CL reaction. Experimental parameters affecting CL inhibition including concentrations of CuO NPs, luminol, H2 O2 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.