Alkaline Luminol Research Articles

A novel luminol chemiluminescence system induced by black phosphorus quantum dots for cobalt (II) detection

Black phosphorus quantum dots (BP QDs) were prepared through a solvothermal exfoliation method in alkaline N-methyl-2-pyrrolidinone. The BP QDs induce distinct chemiluminescence (CL) of alkaline luminol directly. A possible reaction mechanism is proposed by the study of CL spectrum, ultraviolet–visible absorption spectra, electron paramagnetic resonance spectra as well as radical scavenging experiments. The presence of BP QDs significantly increases generation of active oxygen species, which oxidize luminol and lead to intense CL emission at 425 nm. The reaction of luminol with BP QDs are specifically catalyzed by cobalt (II) ion, this presents a sensitive CL method for cobalt (II) ion. A linear response range extends from 2.5 to 2000.0 pmol/L cobalt (II) ion and a detection limit of 0.7 pmol/L (3sb) is acquired. The method displays a good precision approved by a relative standard deviation of 1.9% at 100.0 pmol/L cobalt (II) ion solution (n = 11). A preliminary application of the method was conducted by successful determination of cobalt amount in silica gel and rain water samples.

Comparative study of luminescence and chemiluminescence in hydrodynamic cavitating flows and quantitative determination of hydroxyl radicals production

Luminescence and chemiluminescence have been experimentally investigated in hydrodynamic cavitating flows. By using dedicated microdevices inserted inside a light tight box, photons counting has been made possible. Luminescence has been investigated with deionized water as the working fluid; chemiluminescence has resulted from cavitating alkaline luminol solutions, and has been correlated to hydroxyl radicals formation. For the first time, luminescent and chemiluminescent phenomena have been considered together on the same devices submitted to similar cavitating flow regimes. Degassed solutions enhance the luminescence and also the hydroxyl radical yield. Due to the small sizes of the channels, the lifetimes of the collapsing bubbles correspond to pseudo frequencies matching the range of optimal frequencies used in sonochemistry. New perspectives for the study of hydrodynamic cavitation as an advanced oxidation process are suggested.

Determination of Dopamine Using the Alkaline Luminol–Hydrogen Peroxide System for Sequential Injection–Zone Fluidics Analysis

ABSTRACTLuminol–hydrogen peroxide chemiluminescence was used with photon counting in a tubular reactor with sequential injection analysis and zone fluidics for the determination of dopamine. The analyte was zone stacked and sandwiched between alkaline luminol and hydrogen peroxide solutions separated by air bubbles within head and tail zones inside a holding coil. These zones were reversed and rapidly dispensed into the reactor with zone penetration and trapped inside the cell for measurement by fluid stopped-flow techniques. The linear concentration range for dopamine was from 10−8 to 10−6 mol/L with a relative standard deviation of 3.30% and a limit of detection of 2.60 × 10−9 mol/L. The system provided a relative standard deviation of 2.57% and was used for the determination of dopamine in pharmaceuticals with a recovery of 99.63%.

A novel hybrid flow-injection/sequential-injection methodology for the rapid evaluation of the total antioxidant capacity of wines using inhibition of the alkaline luminol–potassium permanganate chemiluminescent reaction

This work reports the development and validation of a novel hybrid flow injection/sequential injection (FI–SI) method with chemiluminescence (CL) detection for the rapid evaluation of the total antioxidant capacity (TAC) of wines. The method is based on the inhibition of the CL reaction between luminol and potassium permanganate in alkaline medium by the antioxidants in the sample. Zones of sample, potassium permanganate and alkaline luminol were sequentially injected into the carrier stream of the FI–SI manifold. As the zones were delivered to the CL detector, they overlapped and antioxidants in the samples scavenged a portion of potassium permanganate causing a decrease in the CL intensity. The statistical significance of the main chemical and instrumental conditions was studied using a two-level Plackett–Burman experimental design approach and the significant variables were further selected using a univariate approach. The method was validated in terms of linearity, limits of detection (LOD) and quantification (LOQ), accuracy (trueness and precision), matrix effects, and robustness. The linear range for gallic acid (used to express the TAC) was 0.90μmolL−1–15μmolL−1, the LOD was 0.30μmolL−1 and the LOQ was 0.90μmolL−1. The precision of the method (expressed as the % relative standard deviation) was better than 6.4% and the % recoveries in wines were ≥93%. The proposed FI–SI CL method was compared with the DPPH method for the analysis of 25 wine samples.

Gold Nanoparticles‐enhanced Chemiluminescence Determination of Fenfluramine

AbstractA simple and sensitive chemiluminescence method was developed for the determination of fenfluramine. The chemiluminescence signal arising from the reaction between alkaline luminol and N‐bromosuccinimide was found to be greatly enhanced by fenfluramine in the presence of gold nanoparticles. But fenfluramine alone slightly inhibited the CL signal of N‐bromosuccinimide‐luminol in the absence of gold nanoparticles. The experimental parameters that affected the chemiluminescence signal were thoroughly investigated. Under the optimum experimental conditions, the enhanced chemiluminescence intensity was proportional to the concentration of fenfluramine in the range of 0.005‐1.0 mg/L. The detection limit was 0.9 μg/L fenfluramine with a relative standard deviation of 2.5% for 0.1 mg/L fenfluramine solution (n = 11). The method was applied to the determination of fenfluramine in some weight‐reducing tonics and in spiked human urine. A possible CL reaction mechanism was proposed.

Photochemical induced formed Au nanomaterial with size and shape controlled by luminol–pepsin chemiluminescence reaction

The different size and shape AuNMs were generated in the Pep–HAuCl4 system based on the photochemical induced effect of alkaline luminol.

Development of a chemiluminescent method for the evaluation of total hydroperoxide content of edible oils

One of the most important quality indices of edible oils is the total hydroperoxide content expressed as peroxide value (PV). Oils with high hydroperoxide content show a degree of oxidation and, hence, lower quality. For these reasons, the development of methods for the evaluation of this quality index of edible oils is required.The aim of the present work is to develop, a rapid, accurate, sensitive, simple and low cost chemiluminescence (CL) method for the determination of the total hydroperoxide content of different kinds of olive oils and other types of edible oils. The CL method proposed is based on the chemiluminescent reaction of alkaline luminol and the hydroperoxides of oil, catalyzed by Fe(III) using 1-propanol as the reaction solvent. Calibration curves of the CL intensity as a function of concentration of di-tert-butyl peroxide, used as an external peroxide standard, and of different types of edible oils were prepared. In all the cases the correlation coefficient (R) of the regression lines was satisfactory (R>0.996). The precision of the method expressed in terms of repeatability and reproducibility was also satisfactory, as repeatability in terms of mean %RSD was 4.8% and reproducibility in terms of mean %RSD was 8%. The method was applied for the evaluation of total hydroperoxide content of olive oils, corn oils, sunflower oils, sesame oils and soybean oils, within the concentration range of 0.1–9.0%v/v and the obtained results were compared with those of the official method for peroxide value. Finally, the different types of olive oils and seed oils have been classified according to their estimated total hydroperoxide content.

A validated silver‐nanoparticle‐enhanced chemiluminescence method for the determination of citalopram in pharmaceutical preparations and human plasma

A simple and sensitive chemiluminescence (CL) method was developed for the determination of citalopram in pharmaceutical preparations and human plasma. The method is based on the enhancement of the weak CL signal of the luminol-H2 O2 system. It was found that the CL signal arising from the reaction between alkaline luminol and H2 O2 was greatly increased by the addition of silver nanoparticles in the presence of citalopram. Prepared silver nanoparticles (AgNPs) were characterized by UV-visible spectroscopy and transmission electron microscopy (TEM). Various experimental parameters affecting CL intensity were studied and optimized for the determination of citalopram. Under optimized experimental conditions, CL intensity was found to be proportional to the concentration of citalopram in the range 40-2500 ng/mL, with a correlation coefficient of 0.9997. The limit of detection (LOD) and limit of quantification (LOQ) of the devised method were 3.78 and 12.62 ng/mL, respectively. Furthermore, the developed method was found to have excellent reproducibility with a relative standard deviation (RSD) of 3.65% (n = 7). Potential interference by common excipients was also studied. The method was validated statistically using recovery studies and was successfully applied to the determination of citalopram in the pure form, in pharmaceutical preparations and in spiked human plasma samples. Percentage recoveries were found to range from 97.71 to 101.99% for the pure form, from 97.84 to 102.78% for pharmaceutical preparations and from 95.65 to 100.35% for spiked human plasma.

Development of a generic assay for the determination of total trihydroxybenzoate derivatives based on gold-luminol chemiluminescence

A selective assay for the determination of one of the most important class of phenolic compounds, namely trihydroxybenzoates (monomeric and polymeric compounds having at least one gallate moiety) based on their enhancing effect on the chemiluminogenic reaction between gold ions and luminol is described for the first time. In the presence of trihydroxybenzoate derivatives, the light emission generated when alkaline luminol is oxidized by gold ions is amplified several orders of magnitude compared to other common phenolic compounds which exhibit minor reactivity or no reactivity at all (e.g. hydroxycinnamates, flavonols, benzenediols). Based on this property, the experimental conditions were optimized in order to enable the determination of total trihydroxybenzoates in complex mixtures without resorting to separation techniques. The method was applied to samples of different composition (teas, herbal infusions and wines) with satisfactory analytical features yielding detection limits at the 10−7molL−1 level, intra-day precision of 3.1%, inter-day precision less than 10% and recoveries between 88.7 and 97.6%. The strengths and weaknesses of the method were identified and discussed in relation to its application in real samples.

Reusable light-emitting-diode induced chemiluminescence aptasensor for highly sensitive and selective detection of riboflavin

A novel reusable chemiluminescence aptasensor was developed based on aptamer recognition coupled with light-emitting-diode induced chemiluminescence (LED-CL) detection. The sensing approach was based on the design that the model analyte riboflavin (Rf) in sample solutions was captured by the immobilized aptamers and then eluted simply with alkaline luminol solution to catalyze the CL reaction between luminol and dissolved oxygen under high power LED irradiation. This design allowed a very simple (branch-free) flow way for the CL sensing system. The CL intensity versus the Rf concentration was linear in the range from 0.03 to 5ngmL–1 with a limit of detection (LOD) down low to 8pgmL–1. Without renewing the aptamer, the relative standard deviation (RSD) for seven consecutive detections is 2.33%; the sensor also showed good stability without performance deterioration after >100 times use. Up to 10000-fold of K+, Na+, Ca2+, Mg2+, and Fe3+, 5000-fold for glucose and bovine serum albumin, 1000-fold of uric acid, 1500-fold of ascorbic acid (added with Fe3+), 100-fold of flavin mononucleotide and 200-fold of flavin adenine dinucleotide caused no significant interference with the determination of 0.5ngmL–1 Rf. The sensor was applied for analysis of Rf in urine and food samples with the recovery of 94–103%. The advantages of reusability, simplicity, high sensitivity and selectivity provided by the LED-CL aptasensor will make it a good alternative tool for biological and food analysis.

Chemiluminescent Identification and Quantification of Artemisinin and Relevant Sesquiterpene Lactone Derivatives

A simple, sensitive, and rapid chemiluminescence method was developed for the detection and quantification of selected derivatives of artemisinin. It was found that the chemiluminescence (CL) signal resulting from the alkaline luminol reaction of the artemisinin derivatives in the presence of hematin was linear over a wide concentration range. We report results that suggest that a visual test or a test involving digital image capture may be used in addition to a field-ready instrumental approach to combat drug counterfeiting of malarial therapies.

Flow injection analysis of ketoprofen based on the order transform second chemiluminescence reaction

This paper explores an order-transform-second-chemiluminescence (OTSCL) method combining the flow injection technique for the determination of ketoprofen. When ketoprofen solution was injected into the mixture after the end of the reaction of alkaline luminol and sodium periodate or sodium periodate solution was injected into the reaction mixture of ketoprofen and alkaline luminol, a new chemiluminescence (CL) reaction was initiated and strong CL signal was detected. A mechanism for the OTSCL has been proposed on the basis of the chemiluminescence kinetic characteristic, UV–visible absorption and chemiluminescent spectra. Under optimal experimental conditions, the CL response is proportional to the concentration of ketoprofen over the range of 2.0 × 10 −7 to 1.0 × 10 −5 mol/L with a correlation coefficient of 0.9950 and a detection limit of 8.0 × 10 −9 mol/L (3 σ). The relative standard deviation for 11 repetitive determinations of 1.0 × 10 −6 mol/L ketoprofen is 2.9%. The utility of this method was demonstrated by determining ketoprofen in pharmaceutical formulations without interference from its potential impurities.

Development and validation of a sequential-injection method with chemiluminescence detection for the high throughput assay of the total antioxidant capacity of wines

This work reports a sequential-injection analysis (SIA) method with chemiluminescence (CL) detection for the rapid assay of the total antioxidant capacity (TAC) in wines. The method exploited the Co(II)-catalysed CL reaction of luminol with hydrogen peroxide in alkaline medium. Zones of sample, hydrogen peroxide, catalyst (Co(II) solution) and alkaline luminol were sequentially aspirated into the holding coil of the SIA manifold. Then, the flow was reversed and the stacked zones were directed to the CL detector. As the zones overlapped, antioxidants in the samples scavenged a portion of hydrogen peroxide and the decrease in the CL intensity was monitored and related to the TAC. The chemical and geometric conditions were studied and the method was validated in terms of linearity, accuracy (trueness and precision), matrix effects, signal additivity and robustness. The reproducibility of the method (expressed as the between-days % relative standard deviation) was between 2.5 and 3.4% and the trueness (expressed as the % recovery in wines spiked with gallic acid) was in the range 96.7–97.3%. The sampling frequency was 60 samples h−1. The proposed SIA-CL method was compared with the DPPH method and the Folin–Ciocalteau (FC) method for the analysis of 25 wine samples.

Flow‐injection chemiluminescence method for the determination of chloramphenicol based on luminol–sodium periodate order‐transform second‐chemiluminescence reaction

A new chemiluminescence (CL) reaction was observed when chloramphenicol solution was injected into the mixture after the end of the reaction of alkaline luminol and sodium periodate or sodium periodate was injected into the reaction mixture of chloramphenicol and alkaline luminol. This reaction is described as an order-transform second-chemiluminescence (OTSCL) reaction. The OTSCL method combined with a flow-injection technique was applied to the determination of chloramphenicol. The optimum conditions for the order-transform second-chemiluminescence emission were investigated. A mechanism for OTSCL has been proposed on the basis of the chemiluminescence kinetic characteristics, the UV-visible spectra and the chemiluminescent spectra. Under optimal experimental conditions, the CL response is proportional to the concentration of chloramphenicol over the range 5.0 × 10(-7)-5.0 × 10(-5) mol/L with a correlation coefficient of 0.9969 and a detection limit of 6.0 × 10(-8) mol/L (3σ). The relative standard deviation (RSD) for 11 repeated determinations of 5.0 × 10(-6) mol/L chloramphenicol is 1.7%. The method has been applied to the determination of chloramphenicol in pharmaceutical samples with satisfactory results.

Flow-Injection Chemiluminescence Determination of Lisinopril Using Luminol–KMnO<SUB>4</SUB> Reaction Catalyzed by Silver Nanoparticles

A simple, sensitive, and rapid chemiluminescence method combined with flow-injection analysis was developed for the determination of lisinopril. It was found that the chemiluminescence (CL) signal arising from the reaction of alkaline luminol with KMnO(4) could be significantly increased by addition of lisinopril in the presence of silver nanoparticles. The experimental parameters affecting the chemiluminescence reaction were carefully studied and the chemiluminescence reaction mechanism was briefly discussed. Under the selected conditions, the chemiluminescence intensity was proportional to the concentration of lisinopril ranging from 0.1 mg/L to 20.0 mg/L. The detection limit was 0.027 mg/L lisinopril and the relative standard deviation for 4.0 mg/L lisinopril solution was 1.9% over eleven repeated measurements. The proposed method was applied to the determination of lisinopril in tablets and spiked human urine samples.

Sensitive Chemiluminescence Determination of Thirteen Cephalosporin Antibiotics with Luminol—Copper(II) Reaction

A new chemiluminescence reaction, the luminol-Cu(2+) reaction, was investigated for the determination of thirteen (13) cephalosporin antibiotics, namely cefalexin, cefadroxil, cefradine, cefazolin sodium, cefaclor, cefuroxime axetil, cefotaxime sodium, cefoperazone sodium, ceftriaxone sodium, ceftazidime, cefetamet pivoxil hydrochloride, cefixime, and cefpodoxime. It was found that, without adding any special oxidant, strong chemiluminescent (CL) signal could be produced from the reaction of the alkaline luminol with the above-mentioned antibiotics in the presence of Cu(2+). The experimental conditions for the reaction were carefully optimized with flow-injection mode. The detection limits are 0.3 ng/mL cefalexin, 3 ng/mL cefadroxil, 0.3 ng/mL cefradine, 0.02 μg/mL cefazolin sodium, 0.8 ng/mL cefaclor, 0.02 μg/mL cefuroxime axetil, 5 ng/mL cefotaxime sodium, 0.02 μg/mL cefoperazone sodium, 0.8 ng/mL ceftriaxone sodium, 1 ng/mL ceftazidime, 0.08 ng/mL cefetamet pivoxil hydrochloride, 0.8 ng/mL cefixime, and 2 ng/mL cefpodoxime. The proposed method was validated by direct application to commercial formulations and spiked milk samples containing cefradine. A possible reaction mechanism is also discussed.

Antioxidative activity of the buckwheat polyphenol rutin in combination with ovalbumin

Buckwheat flour is well known for its highly antioxidative ingredient, rutin. We have undertaken to examine alterations in the characteristics of rutin treated with various proteins. In this study, the radical scavenging activities of a rutin-ovalbumin complex were examined. Dissolved rutin hydrate and ovalbumin were combined and boiled in water for 10 min. In the resulting rutin-ovalbumin complex, a new high molecular weight peak was detected using gel permeation chromatography analysis, and an existing high molecular weight area of ovalbumin was observed to be increased by the addition of rutin. This suggested that ovalbumin molecules produce a complex through their interaction with rutin. Alkaline luminol chemiluminescence and electron spin resonance analysis revealed the formation of a rutin-ovalbumin complex that markedly enhanced the peroxyl, but not the hydroxyl, radical scavenging activity of rutin. Rutin also demonstrated antioxidative activity against hydroxyl radicals in a DNA protection assay. We therefore conclude that, compared with ovalbumin or rutin alone, the rutin-ovalbumin complex has improved antioxidative activities in the form of enhanced peroxyl radical scavenging activity and DNA protection from apurinic/apyrimidinic site formation caused by hydroxyl radicals.

Selectivity and potential interference from phenolic compounds in chemiluminescence methods for the determination of synephrine

Three recently reported chemiluminescence methods (based on reactions with alkaline luminol and hexacyanoferrate(III); acidic cerium(IV) and rhodamine B; and acidic permanganate with polyphosphates) for the determination of synephrine were re-evaluated in terms of their selectivity towards this analyte in comparison to other phenolic compounds. A fourth reagent system, acidic soluble manganese(IV) and formaldehyde, was also examined. Each set of reagents was sensitive towards synephrine (limits of detection were 3 x 10(-9), 5 x 10(-8), 1 x 10(-8) and 1 x 10(-8) mol/L, respectively) but also responded with numerous other phenolic compounds, including some that are present in citrus fruit extracts, dietary supplements and/or biological fluids. It is therefore recommended that the determination of synephrine in these matrices should incorporate physical separation of sample components (e.g. chromatography or electrophoresis). In more general terms, this study illustrates that accurate percentage recoveries for an analyte in spiked samples (without validation against another analytical method) are insufficient to confirm the analytical utility of new flow-injection analysis (FIA) procedures.

A miniaturized flow-injection analysis ( μ FIA) system with on-line chemiluminescence detection for the determination of iron in estuarine water

A miniaturized flow-injection analysis system constructed from a glass base plate and polydimethylsiloxane (PDMS) top plate was employed for the determination of iron in river water. Two designs were investigated, one utilizing a syringe pump and the other utilizing EOF pumping with a mini-filtration system incorporated. The syringe pump system was used to optimize the analytical method on chip, where the pump was used to deliver both the analyte and the reagents to the reactor chip. The highly sensitive chemiluminescence reaction between alkaline luminol (3-aminophthalhydrazide) and 0.1 M of hydrogen peroxide (H2O2) in the presence of iron(II) was utilized. The bright blue light (λ max ∼ 440 nm) emitted was detected using a miniaturized photomultiplier tube interfaced directly under the chip. The light intensity signals were recorded, and the corresponding concentration of iron(II) concentration was determined. The calibration for iron(II) standards was linear up to 0.75 µg mL−1 (y = 5.7839x + 0.0378, r2 = 0.9939) with a precision value of up to 3.72% RSD, for n = 3. The limits of detection (blank + 3s y/x) were found to be 28 ng mL−1. The system which utilized EOF pumping and incorporated a minifiltration unit provided a linear calibration for 0–5 µg mL−1 (y = 3.316x + 0.1831; correlation coefficient, r 2 = 0.9996) over a working range of 0.0–0.5 µg mL−1. This system provided lower limits of detection 5.1 ng mL−1 and better repeatability (%RSD less than 0.5% for n = 4), but problems occurred with the mini-filtration system at higher iron(II) concentrations. The EOF pumping system provided slightly higher results for the concentration of iron(II) in the Humber estuary (0.058 µg mL−1), but these results were in line with the results expected by the Environment Agency.

Miniaturized flow-injection-analysis (μFIA) system with on-line chemiluminescence detection based on the luminol-hypochlorite reaction for the determination of ammonium in river water

A miniaturized flow-injection-analysis system constructed from glass and polydimethylsiloxane was employed for the determination of ammonium in river water. The sample was filtered and delivered to the reactor chip electro-osmotically using a disposable fritted capillary, while reagents were delivered to the system by gravity. Ammonia was mixed with the hypochlorite, to form a monochloramine. Once the alkaline luminol (3-aminophthalhydrazide) was delivered to the system, it was oxidized by the unconsumed hypochlorite emitting a bright blue light (λ max ∼ 440 nm) that was detected using a miniaturized photomultiplier tube (PMT) located directly under the chip. The calibration model for ammonium standards was linear up to 0.1 µg mL−1 (y = −8.96x + 1.02; correlation coefficient, r 2 = 0.9715) over a working range of 0.0–0.5 µg mL−1. A detection limit of 10 ± 6 µg mL−1 was achieved with a precision value of (RSD ≤ 6.4%), for n = 5. A direct and standard addition method were used to determine the concentration of ammonium in a river-water sample (from the Humber Estuary, UK) which was found to be 0.075 ± 0.005 µg mL−1, with a precision value of (RSD ≤ 3.7%), for n = 9. The results obtained showed good agreement with the average concentration 0.065 µg mL−1 (provided by the local environmental agency), for the analysis of ammonia at different sample points on the estuary.