A chemiluminescence reaction between hydrogen peroxide and acetonitrile and its applications

Sonochemical synthesis of gum guar biopolymer stabilized copper oxide on exfoliated graphite: Application for enhanced electrochemical detection of H2O2 in milk and pharmaceutical samples

A novel and cost-effective synthesis of biopolymer-based organic and inorganic composite materials have received substantial attention in a broad range application including electroanalysis of small molecules. In this perspective, we report the synthesis of gum guar (guar) biopolymer stabilized cupric oxide decorated on exfoliated graphite (GR-guar/CuO) composite. Different physicochemical characterization methods were used to confirm the successful exfoliation of graphite and formation of the GR-guar/CuO composite. A simple sonochemical method has been used for the preparation of guar stabilized exfoliated graphite (GR-guar). The flower-like CuO on GR-guar and guar stabilized CuO (CuO-guar) composites were synthesized using a hydrothermal method. Cyclic voltammetric studies revealed that the GR-guar/CuO composite modified screen-printed carbon electrode (SPCE) had enhanced electro-reduction ability towards H₂O₂ than GR-guar and pristine graphite/CuO-guar modified SPCEs. Under optimized experimental conditions, the GR-guar/CuO composite modified electrode detects H₂O₂ in the response ranges from 0.02 to 1296.6 µM. The sensor shows a lower detection limit of 5.8 nM with high sensitivity. The as-prepared GR-guar/CuO composite sensor is highly reproducible and had excellent selectivity and practicality towards the detection of H₂O₂. Consequently, the fabricated sensor can be used for the accurate detection of H₂O₂ in real samples.

Chemiluminescence molecular probe with a linear chain reaction amplification mechanism

A new signal amplification probe with a linear chain reaction amplification mechanism and distinct chemiluminescence output was developed.

Just Add Luminol to Turn the Spotlight on Radziszewski Amidation

Radziszewski amidation, namely the peroxide-mediated conversion of nitriles into amides, is a chemiluminescent reaction involving singlet oxygen. Its increasing relevance in green chemistry and analytical chemistry makes it an important subject to be discussed in advanced chemistry courses. To turn the attention of lecturers, teachers, and students toward this reaction, the history of its discovery as well as its practical applications is discussed. Moreover, a simple and effective experiment to demonstrate the chemiluminescent properties of Radziszewski amidation is provided.

Electrosynthesis of bismuth nanodendrites/gallium nitride electrode for non-enzymatic hydrogen peroxide detection

Bismuth nanodendrites (BiNDs) were electrodeposited on planar gallium nitride (GaN) electrode via a differential pulse voltammetric technique to fabricate the non-enzymatic hydrogen peroxide (H₂O₂) sensor. SEM images revealed that the as-obtained BiNDs had numerous dendrite sub-branches, whose diameters ranged from 136 to 152nm. The BiNDs/GaN electrode showed linear amperometric responses for H₂O₂ in the concentration range from 10µM to 1mM with the sensitivity of 60.0μAmM^-1cm^-2. Another linear range was from 1 to 10mM with the sensitivity of 23.3μAmM^-1cm^-2. The limit of detection (LOD) was 5µM with the signal-to-noise ratio of 3. The applicability of the sensor was investigated to the H₂O₂ detection in real samples such as fetal bovine serum and milk, and the sensor exhibited excellent anti-interference capacity. The achieved results indicate that the as-prepared BiNDs/GaN sensor with good reproducibility and long-term stability was promising for detecting H₂O₂ in practical environments.

A non-enzymatic amperometric hydrogen peroxide sensor based on iron nanoparticles decorated reduced graphene oxide nanocomposite

A simple and facile green process was used for the synthesis of iron nanoparticles (FeNPs) decorated reduced graphene oxide (rGO) nanocomposite by using Ipomoea pes-tigridis leaf extract as a reducing and stabilizing agent. The as-prepared rGO/FeNPs nanocomposite was characterized by transmission electron microscopy, X-ray spectroscopy and Fourier transform infrared spectroscopy. The nanocomposite was further modified on the glassy carbon electrode and used for non-enzymatic sensing of hydrogen peroxide (H₂O₂). Cyclic voltammetry results reveal that rGO/FeNPs nanocomposite has excellent electro-reduction behavior to H₂O₂ when compared to the response of FeNPs and rGO modified electrodes. Furthermore, the nanocomposite modified electrode shows 9 and 6 folds enhanced reduction current response to H₂O₂ than that of rGO and FeNPs modified electrodes. Amperometric method was further used to quantify the H₂O₂ using rGO/FeNPs nanocomposite, and the response was linear over the concentration ranging from 0.1μM to 2.15mM. The detection limit and sensitivity of the sensor were estimated as 0.056μM and 0.2085μAμM^-1cm^-2, respectively. The fabricated sensor also utilized for detection of H₂O₂ in the presence of potentially active interfering species, and found high selectivity towards H₂O₂.

Peroxide induced ultra-weak chemiluminescence and its application in analytical chemistry

Chemiluminescence (CL), as a sensitive, rapid, and facile analytical method, has been widely applied in environmental monitoring, clinical diagnosis and food safety. Recently, the main challenge and research interest in the CL study have been focused on exploring new CL systems and obtaining new insight into the interaction between CL reagents. The peroxide induced ultra-weak CL reactions are some new arising systems that have received great attention and have been successfully applied in many fields. The peroxide includes hydrogen peroxide, peroxynitrite, peroxymonocarbonate, peroxomonosulphate and so on. This review paper covers the mechanism of the peroxide induced ultra-weak CL and the analytical applications of the CL have also been summarized. The future prospects for the peroxide induced ultra-weak CL are discussed.

Enhancement of chemiluminescence of the KIO4-luminol system by gallic acid, acetaldehyde and Mn2+: application for the determination of catecholamines

Chemiluminescence (CL) from the oxidation of luminol with potassium periodate in strong alkaline solutions was greatly enhanced by the combined effect of gallic acid, acetaldehyde and Mn(2+). The CL spectra exhibited only one emission band at 425 nm, indicating 3-aminophthalate as the emitting species. Various scavengers for superoxide anion, hydroxyl radical and singlet oxygen quenched the CL emission very efficiently (74-100%), suggesting the possible involvement of these reactive oxygen species (ROS) in the CL reactions. It is postulated that oxidation of gallic acid and acetaldehyde by periodate catalyzed by Mn(2+) generates these ROS, which then react with luminol to enhance the CL emission. We also found that the enhanced CL emission was strongly inhibited by catecholamines, probably because of their effective scavenging of ROS. Based on this observation, a simple, rapid and sensitive new CL method was developed for the determination of catecholamines. The detection limits (3sigma) for dopamine, l-dopa, norepinephrine and epinephrine were 0.63, 1.37, 0.56 and 14.3 nmol/L, respectively. The linear range was 1-10 nmol/L; relative standard deviations were 0.71-1.34% for 0.1 micromol/mL catecholamines. This CL method was applied to the determination of catecholamines in pharmaceutical injections with satisfactory results.

Chemiluminescence platforms in immunoassay and DNA analyses

Chemiluminescent (CL) detection techniques for DNA assays and immunoassays have become very popular in recent years. This review discusses recent advances in those CL assays that have occurred over the last few years. In the monoplex assay section, different classes of CL labels including nanoparticle, DNAzyme, acridinium ester, enzyme and luminol-based CL assays are reviewed concerning the detection of DNAs and proteins. In the multiplex assay section, both spatial resolution and substrate zone-resolved techniques are discussed.

Determination of cortisol in human blood sera by a new Ag(III) complex-luminol chemiluminescent system

A new chemiluminescence (CL) system based on the reaction of Ag(III) complex with luminol is, for the first time, reported in this work. Incorporated with a flow injection analyses (FIA), the new CL system has been applied for the determination of free cortisol in human sera. The system is based on the CL reaction of luminol with Ag(III) in alkaline solutions, while cortisol can dramatically enhance CL intensities. Under optimum conditions, CL intensities are proportional to concentration of cortisol in the range of 0.05-7.5 nM. The limit of detection is 2.0x10(-11) M (3sigma), with a relative standard deviation (n=11) of 1.9% for 3.5x10(-9) M cortisol. Eight human blood serum samples were all handled by solid-phase extraction (SPE) clean-up and enrichment before detection. This detection system is highly sensitive and convenient and may find wide applications. Based on the chemiluminescent spectra, a possible reaction mechanism is also suggested.

New method for the photo-chemiluminometric determination of benzoylurea insecticides based on acetonitrile chemiluminescence

The viability of tandem photochemical reaction-chemiluminescence detection has been studied for the determination of five benzoylurea insecticides, namely, diflubenzuron, triflumuron, hexaflumuron, lufenuron and flufenoxuron. The 'on-line' photochemical reaction of benzoylurea pesticides provides an enhanced chemiluminescence response of the pesticides during their oxidation by potassium hexacyanoferrate(III) and sodium hydroxide, whose signal increases with the percentage of acetonitrile in the reaction medium. The determination was performed using a photoreactor consisting of a PFA (perfluoroalkoxy) tube reactor coil (5 mx1.6-mm O.D. and 0.8-mm I.D.) and an 8-W xenon lamp. As the yield of the photoderivatization process and the chemiluminescent signals depend on the percentage of acetonitrile, the chromatographic column (a Gemini C18, Phenomenex 150 mmx4.6 mm, 5-microm particle size) was chosen with the aim of using high percentages of this organic solvent in the mobile phase. Previous studies showed that the rate of the chemiluminescent reaction was very fast. Therefore, a modification was carried out in the detector in order to mix the analytes and reactants as near as possible to the measure cell. The optimised method was validated with respect to linearity, precision, limits of detection and quantification accuracy. Under the optimised conditions, linear working range extends three orders of magnitude with the relative standard deviation of intra-day precision below 10% and detection limits between 0.012 and 0.18 microg mL-1, according to the compound. The proposed method has been successfully applied to the determination of benzoylureas in cucumber with good results.

Flow Injection Chemiluminescence Determination of Imipramine in Tablets, Human Plasma and Urine Samples Based upon Oxidation with Singlet Oxygen Generated in N-Bromosuccinimide-Hydrogen Peroxide Reaction

Singlet oxygen generated in a reaction between N-bromosuccinimide and hydrogen peroxide was used for the chemiluminescence oxidation of imipramine. A strong chemiluminescence signal was observed when imipramine was mixed with N-bromosuccinimide and hydrogen peroxide under an alkaline condition. The chemiluminescence signal was linearly dependent on the concentration of imipramine in the range of 0.01 - 1.0 mg/L. The detection limit was 0.005 mg/L imipramine and the relative standard deviation was 1.5% for a 0.4 mg/L imipramine solution in 11 repeated measurements. The proposed method was successfully applied to the determination of imipramine in tablets, human plasma and urine samples.

Flow injection chemiluminescence determination of nitrofurazone in pharmaceutical preparations and biological fluids based on oxidation by singlet oxygen generated in N-bromosuccinimide–hydrogen peroxide reaction

A simple flow injection chemiluminescence (FI-CL) method was proposed for the determination of nitrofurazone. Strong CL signal was generated during the reaction of nitrofurazone with H(2)O(2) and N-bromosuccinimide (NBS) in alkaline condition. The CL signal was proportional to the nitrofurazone concentration in the range 1.0 x 10(-7) to 1.0 x 10(-5) g mL(-1). The detection limit was 2 x 10(-8) g mL(-1) nitrofurazone and the relative standard deviation was less than 4% (6.0 x 10(-6) g mL(-1) nitrofurazone, n=11). The proposed method was successfully applied to the determination of nitrofurazone in compound furacillin nasal drops, human plasma and urine samples. The CL reaction mechanism was also discussed briefly. Singlet oxygen generated in the reaction between H(2)O(2) and NBS was suggested to be participated in the CL reaction.

Determination of nine pyrethroid insecticides by high-performance liquid chromatography with post-column photoderivatization and detection based on acetonitrile chemiluminescence

An HPLC method was developed to determine pyrethroids, including fenpropathrin, beta-cyfluthrin, lambda-cyhalothrin, deltamethrin, fenvalerate, permethrin, acrinathrin, tau-fluvalinate, and bifenthrin, by coupling HPLC, post-column irradiation with UV light and chemiluminescence detection of the resulting photoproducts. It is based on the observation that photolyzed pyrethroids take part in a chemiluminescent reaction in presence of K3Fe(CN)6 and NaOH, whose signal increases with the percentage of acetonitrile in the reaction medium. As the yield of the photoderivatization process and the chemiluminescent signals depend on the percentage of acetonitrile, the chromatographic column (a Gemini C18, Phenomenex 150 mm x 4.6 mm, 5 microm particle size) was chosen with the aim of using high percentages of this organic solvent in the mobile phase. Previous studies showed that the rate of the chemiluminescent reaction was very fast. Therefore, a modification was carried out in the detector in order to mix the analytes and reactives as near as possible to the measure cell. The optimised method was validated with respect to linearity, precision, limits of detection and quantification accuracy. Under the optimised conditions, linear working range extends three orders of magnitude with the relative standard deviation on intra-day precision below 10% and detection limits between 0.013 and 0.049 microg mL(-1), according to the compound. The proposed method has been successfully applied to the determination of pyrethroids in tomato with good results.

Sensitivity enhancement of liquid chromatographic–direct chemiluminescence detection by on-line post-column solvent mediated pre-oxidative chemiluminescence

The compatibility of liquid chromatography solvents with oxidizing reagents frequently employed in direct chemiluminescence reactions is examined in this study. Various oxidizing reagents were examined for their response in hydro-organic and micellar mobile phases in both isocratic and gradient elution modes. Mild oxidants like hydrogen peroxide, periodate, cerium and hypochlorite were found to be completely compatible with common reversed phase HPLC solvents posing as no threat to the detection procedure. On the other hand, stronger oxidants like acidic permanganate were found to oxidize organic solvents towards the production of an intense light signal. Although several analytical applications can emerge from this finding, the conjunction of this system with reversed phase HPLC is impractical owing to a significant baseline increase which deteriorates the sensitivity of the analysis. A convenient solution to this problem is proposed based on the regulated on-line post-column pre-oxidation of the organic solvent (SPOC) with mild oxidants that have no influence on the final signal. The analytical utility of this new approach in the determination of organic compounds after chromatographic separation is demonstrated.

Investigation on the interaction between dihydroxybenzene and Fe3+–H2O2–Rh6G system based on enhancing chemiluminescence

A highly sensitive flow-injection chemiluminescence (FI-CL) method has been developed for the determination of dihydroxybenzene, based on the hydroxyl radical reaction. Hydroxyl radical (.OH) produced by the reaction of Fe(3+) and H(2)O(2) oxidize rhodamine 6G to produce weak CL. It was observed that catechol and hydroquinone greatly enhanced the weak CL reaction. However, the proposed CL system is not suitable for determination of resorcinol because the enhancement reaction is very slow. The proposed procedure has a linear range of 0.01-2 mg/L for catechol, with a detection limit of 0.006 mg/L, and 0.008-1 mg/L for hydroquinone, with a detection limit of 0.004 mg/L. The possible mechanism of the CL system is discussed.

Application of a new chemiluminescence method for the determination of glucose-6-phosphate dehydrogenase activity in healthy and enzyme-deficient individuals

INTRODUCTION

A chemiluminescence (CL) technique, which determines the glucose-6-phosphate dehydrogenase (G-6-PD) activities in healthy, heterozygous, and completely enzyme-deficient individuals was applied.

METHODS

CL intensities were detected for 4 h at 15-min intervals in each sample with or without addition of G-6-PD substrates into the reaction mixture.

RESULTS

The results revealed an inverse correlation to the reference UV method (Zinkham method; r=-0.80). Furthermore, the CL assay was able to detect G-6-PD activities as low as 0.2 IU/gHb, which was not possible by the UV method.

DISCUSSION

In conclusion, we believe that this method offers a new diagnostic tool for the detection of G-6-PD activities in enzyme-deficient individuals and, because of its increased sensitivity, makes it amenable for determining the effects of different pharmaceutical agents on G-6-PD activity in tissue or cell cultures.

A simple and sensitive chemiluminescence method for the determination of tiopronin for a pharmaceutical formulation

Here we report a rather simple and convenient chemiluminescence (CL) method for the determination of tiopronin. It was based that tiopronin could greatly enhance CL between H2O2 and luminol in a basic alkaline solution. Light emission is intense, and even with a simple setup a high sensitivity could be achieved. The linear range was 3 mM-500 nM with a detection limit of 200 nM. Singlet oxygen and hydroxyl radical were suggested to be produced in this reaction and was responsible for the CL of tiopronin. As a preliminary application, this simple method has been successfully applied into the determination of tiopronin in a pharmaceutical formulation.

Chemiluminescence detection in HPLC and CE for pharmaceutical and biomedical analysis

The present paper reviews the developments and applications of chemiluminescence detection with HPLC and CE in pharmaceutical and biomedical analysis. The chemiluminescence systems, chemiluminogenic reagents and derivatization reagents, improvements in instrumental design as well as their contributions to the practical applications, are all presented. The advantages and limitations of current detection methodology and future prospects for improvement are briefly discussed.

Sensitive determination of a beta-lactam antibiotic, cefaclor by liquid chromatography with chemiluminescence detection

We present a sensitive method for the determination of cefaclor (CCL), a beta-lactam antibiotic. It was based on the chemical derivatization of the drug with 4-(2'-cyanoisoindolyl)phenylisothiocynate (CIPIC) under the reaction conditions with heating at 80 degrees C for 7 min in the presence of pyridine. The CIPIC reagent could react with the primary amino group of the drug to form the CIPIC-conjugated CCL. The derivatives emitted not only fluorescence (FL) at maximum emission wavelength of 410 nm with irradiation at 310 nm, but also chemiluminescence (CL) in the presence of H(2)O(2), borate buffer (pH 9.6) and acetonitrile. After separation of the CIPIC derivatives of CCL and cephradine as internal standard in human serum by reversed-phase liquid chromatography, the derivatives could be monitored with both FL and CL detections. The detection limit (S/N=3) in the chromatograph was 1 pmol by the CL detection and 10 pmol by the FL detection. The proposed CL method permitted the most sensitive determination of CCL in the human serum after its oral administration.