Sensitive Determination of Nanogram Levels of Diacerein in a Pharmaceutical Formulation by Flow Injection Chemiluminescence Analysis

A simple, sensitive and inexpensive flow injection chemiluminescence (FI‐CL) method for the determination of diacerein was proposed. It was based on the greatly enhancive effect of diacerein on the CL reaction between luminol and hydrogen peroxide in alkaline medium. The enhanced CL intensity was linear with the concentration of diacerein over the range 1.0–500 ng/mL with a detection limit (3σ) of 0.2 ng/mL. The relative standard deviation was 1.1% (n = 8, 20 ng/mL diacerein) and the sample throughput was about 120 samples h^?1. This simple method has been successfully applied for the determination of diacerein in a pharmaceutical formulation without interference from its potential impurities. The degradation of diacerein was also investigated briefly.     

Picomole‐level Formaldehyde Determination in Gaseous and Beer Samples Using Flow Injection Chemiluminescence Analysis

Based on the linear enhancement of formaldehyde (FA) within 7.0 ～ 1000 pmol l^?1 on luminol—bovine serum albumin (BSA) chemiluminescence (CL) system, FA determination in air and beer samples using CL with flow injection (FI) was proposed. The detection limit was 2.5 pmol l^?1 (3σ) and the relative standard deviations were less than 4.5% (n = 7). At a flow rate of 2.0 mL min^?1, a whole analysis from sampling to washing only needed 32 s, offering a sample throughput of 112 h^?1. This proposed method was successfully utilized to determine FA vapor pressure in liquid (121.8 ± 3.8 Pa), FA content in real air sample (8.93 ± 0.03 mg m^?3), and FA levels in beer (199.5 ± 5.6 ～ 225.2 ± 3.5 mg l^?1), giving determination recoveries from 90.7% to 109.3%. The mechanism of BSA—FA interaction was also investigated, showing FA binding to BSA was a spontaneous process mainly through hydrogen bonding and van der Waals force by FI‐CL, with binding constant K of 1.89 × 10⁶ l mol^?1 and the number of binding sites n of 0.86. Molecular docking analysis further revealed FA could enter into the pocket at subdomain IIA of BSA, with K of 1.71 × 10⁵ l mol^?1 and ΔG of ‐29.68 kJ mol^?1.     

Determination of Total Chromium in Biological Samples by Automated Reagent Injection Chemiluminescence Analysis

A sensitive method for the determination of total chromium in real samples by flow injection–chemiluminescence (FI–CL) analysis was proposed. It was found that the CL intensity from luminol–lysozyme reaction could be markedly quenched, and the decrease of CL intensity was linear with the logarithm of Cr(III) concentrations over the range of 5.0 to 4000 pg mL^?1 with a detection limit of 2.0 pg mL^?1 (3σ) and relative standard deviations (RSDs) of 3.0, 2.6, and 2.0% for 10, 100, and 1000 pg mL^?1 Cr(III) (n = 7), respectively. At a flow rate of 2.0 mL min^?1, the whole process including sampling and washing could be accomplished within 36 s. The proposed CL method was successfully applied to the determination of total chromium in pharmaceutical capsules, a dietary supplement, and spiked human serum samples, with recoveries from 92.2 to 108.4% and RSDs of less than 4.0%. Using the homemade FI–CL model, the binding constant (K = 4.38 × 10⁶ L mol^?1) and the binding sites (n ≈ 1) of Cr(III) to lysozyme were given.     

Rapid determination of subnanogram urapidil using flow injection enhancement chemiluminescence

A sensitive flow-injection (FI) chemiluminescence (CL) for the determination of urapidil is described in this paper. It is based on the enhancement effect of urapidil on the CL reaction between luminol and hydrogen peroxide. The increment of CL intensity is proportional to the concentration of urapidil in the range 0.1−10 ng/mL (R ²=0.9986), with a detection limit (3σ) of 0.03 ng/mL. The whole process, at a flow rate of 2.0 mL/min, including sampling and washing, could be completed in 0.5 min, and the relative standard deviation (RSD) at the concentration of 0.1, 1.0, and 10.0 ng/mL was less than 3.0% (n = 5). The proposed method has been successfully applied for the determination of urapidil in pharmaceutical preparation, human urine, and serum. The text was submitted by the authors in English.     

Sensitive determination of sub-nanogram amounts of rutin by its inhibition on chemiluminescence with immobilized reagents

An interesting inhibitory effect of rutin on the chemiluminescence (CL) reaction between luminol and periodate was reported, and this effect was used for the determination of rutin in medicine and human urine. The CL reagents, luminol and periodate, were both immobilized on an anion-exchange column. The CL signal produced by the reaction between luminol and periodate, which were eluted from the column through water injection, was decreased in the presence of rutin. Rutin was sensed by measuring the decrement of CL intensity, and which was observed to be linear over the logarithm of 0.1-30 ngml(-1) rutin concentration range, and the limit of detection was 0.03 ngml(-1) (3sigma). At a flow rate of 2.0 mlmin(-1), both sampling and washing could be performed in 0.5 min with a relative standard deviation of less than 3.0%. The method proposed offered reagent-less procedures and remarkable stability in the determination of rutin, and could be easily reused over 80 h. The method proposed was applied successfully in the determination of rutin in pharmaceutical preparations and monitoring the excretion of rutin in human urine.     

Determination of Picogram Amounts of Dihydroxybenzenes in Water Samples with Luminol–lysozyme Chemiluminescence System

An ultrasensitive method for the determination of dihydroxybenzens by flow injection (FI) chemiluminescence (CL) analysis was proposed for the first time. It was found that the CL intensity of luminol–lysozyme system could be significantly inhibited by dihydroxybenzens. The CL intensity decrements were linear with the logarithm of dihydroxybenzens concentrations over the ranges of 1.0 ～ 700 pg mL^‐1 for hydroquinone (HQ), 5.0 ～ 700 pg mL^‐1 for catechol (CT) and 10 ～ 7000 pg mL^‐1 for resorcinol (RS), with the corresponding limits of detection of 0.7, 3.0 and 7.0 pg mL^‐1, respectively. The proposed method was successfully applied to the determination of CT in tap water, rain water, river water and HQ in waste photographic developer samples, with recoveries from 93.5 to 105.8% and relative standard deviations (RSDs) less than 4.0% (n = 5). The possible interaction mechanism of lysozyme with dihydroxybenzens was discussed, and CT to lysozyme's binding constant and the thermodynamic parameters were given by the homemade FI–CL model. The results shown that the binding of dihydroxybenzens to lysozyme was spontaneous with the hydrophobic force.     

Human Saliva-Based Quantitative Monitoring of Clarithromycin by Flow Injection Chemiluminescence Analysis: A Pharmacokinetic Study

Human saliva quantitative monitoring of clarithromycin (CLA) by chemiluminescence (CL) with flow injection analysis was proposed for the first time, which was based on the quenching effect of CLA on luminol–bovine serum albumin (BSA) CL system with a linear range from 7.5?×?10^?4 to 2.0 ng/ml. This proposed approach, offering a maximum sample throughput of 100 h^?1, was successfully applied to the quantitative monitoring of CLA levels in human saliva during 24 h after a single oral dose of 250 mg intake, with recoveries of 95.2～109.0 % and relative standard deviations lower than 6.5 % (N?=?7). Results showed that CLA reached maximum concentration of 2.28?±?0.02 μg/ml at approximately 3 h, and the total elimination ratio was 99.6 % in 24 h. The pharmacokinetic parameters including absorption rate constant (0.058?±?0.006 h^?1), elimination rate constant (0.149?±?0.009 h^?1) and elimination half-life time (4.66?±?0.08 h) were obtained. A comparison of human saliva and urine monitoring was also given. The mechanism study of BSA–CLA interaction revealed the binding of CLA to BSA is an entropy driven and spontaneous process through hydrophobic interaction, with binding constant K _BSA–CLA of 4.78?×?10⁶ l/mol and the number of binding sites n of 0.82 by flow injection–chemiluminescence model. Molecular docking analysis further showed CLA might be in subdomain IIA of BSA, with K _BSA–CLA of 6.82?×?10⁵ l/mol and ΔG of ?33.28 kJ/mol.     

Chemiluminescence assay for uric acid in human serum and urine using flow-injection with immobilized reagents technology

A novel chemiluminescence (CL) flow sensor for the determination of uric acid in human urine and serum has been developed by using controlled-reagent-release technology. The reagents involved in the chemiluminescence (CL) reaction, luminol and periodate, are immobilized on anion-exchange resin packed in a column. After injection of water, chemiluminescence generated by released luminol and periodate in alkaline media is inhibited in presence of uric acid. By measuring the decreased chemiluminescence (CL) intensity the uric acid is sensed. The decreased response is linear in the 5.0-500.0 ng mL(-1) range, with a detection limit of 1.8 ng mL(-1). The flow sensor showed remarkable operational stability and could be easily reused for over 80 h with sampling frequency of 100 h(-1). The proposed sensor was applied to the determination of uric acid in human urine and serum, and monitoring metabolic uric acid in human urine with RSD less than 3.0%.     

A Novel Electrogenerated Chemiluminescence Reaction Scheme Using Core-Shell LuminoI-Based SiO2 Nanoparticles as a Regulator and Its Analytical Application

A novel core-shell luminol-based SiO2 nanoparticle While these nanoparticles were used as electrogenerated was synthesized by two step micro-emulsion method. chemiluminescence （ECL） reagent, the electrochemical （EC） reaction as well as the subsequent chemiluminescence （CL） reaction not only could be separated spatially, but also presented high efficiency for analytical purpose. In this case, the core-shell luminol-based SiO2 nanoparticles offered more potential to avoid the contradiction between the EC and the CL reaction conditions. A new ECL method based on the nanoparticle was developed, and isoniazid was selected as a model analyte to illustrate the characteristics of this new ECL method. Under the selected conditions, the proposed ECL response to isoniazid concentration was linear in the range of 1.0 ×10^-10 to 1.0 × 10^-6 g/mL with 2 × 10^-11g/mL detection limit.     

Ultrasensitive Assay of Gatifloxacin at Picogram Level Based on its Enhancing Effect on the Myoglobin‐Luminol Chemiluminescence Reaction

Abstract

Picogram‐level gatifloxacin was determined based on its significantly catalyzed effect on myoglobin‐luminol chemiluminescence (CL) reaction in the flow injection system. The enhanced chemiluminescence intensity was linear with gatifloxacin concentration in the range from 50 ngl^?1–10 µg l^?1 (r²=0.9995), and the detection limit was 20 ng l^?1 (3σ). At a flow rate of 2.0 ml min^?1 for each line, a complete analytical process could be performed within 0.5 min, including sampling and washing, with a relative standard deviation of less than 4.0% (n=7). The proposed method was applied successfully in the determination of gatifloxacin in tablets, human serum and urine samples with the recovery from 97.4–104.5%.     

Chemiluminometric Determination of the Pesticide Pirimicarb by a Flow Injection Analysis Assembly

Abstract

A flow injection (FI) method is described for the determination of pirimicarb. It was found that an enhanced chemiluminescence (CL) signal is obtained when employing the luminol–H₂O₂–horseradish peroxidase (HRP) system. Under the optimum experimental conditions, the enhanced CL intensity was linear with the concentration 4.25–30.75 ng mL^?1 (r = 0.997, n = 8) with a relative standard deviation of 0.99%, containing 12.75 ng mL^?1 (n = 8). The limit of detection of the investigated compound was 0.12 ng mL^?1. The method shows a moderate selectivity against other pesticides (Amitrole, Atrazine, 2,4,5-T, Dichlorprop, and Metamidophos).The proposed method was sensitive, simple, rapid, and successfully applied to the determination of pirimicarb when it is applied in freshwater; the mean recoveries were 98.3–118.5%.     

Chemiluminescence flow system for the determination of sulfite

A novel chemiluminescence(CL) flow system for sulfite is described based on electrostatically immobilized luminol on an anion exchange column. Sulfite is detected by the CL reaction with luminol bleeding from the column by hydrolysis. The calibration graph is linear in the range 3 × 10^–7 to 1 × 10^–5 mol/L, and the detection limit is 1 × 10^–7 mol/L. Interfering metal ions co-existing in sample solutions could be effectively eliminated on-line by an upstream cation exchanger. A complete analysis could be performed in 1 min with a relative standard deviation of less than 5%. The system could be reused for over 50 h and has been applied successfully to the determination of sulfur dioxide in air.     

On-Line Monitoring of Formaldehyde In Water and Air Using Chemiluminescence Detection

A rapid and sensitive chemiluminescence flow sensor for the determination of formaldehyde was proposed in this article. The analytical reagents involved in chemiluminescence (CL) reaction, luminol and KIO₄, were both immobilized on an anion-exchange column. The CL signal produced by the reaction between luminol and KIO₄, which were eluted from the column through water injection, was decreased in the presence of formaldehyde. Formaldehyde was sensed by measuring the decrement of CL intensity, which was observed linear over the logarithm of formaldehyde concentration range of 5.0-1000.0 ng mL^?1, and the limit of detection is 1.8 ng mL^?1 (3σ). At a flow rate of 2.0 mL min^?1, including sampling and washing, could be performed in 0.5 min with a relative standard deviation of less than 3.0%. The flow sensor offered reagentless procedures and remarkable stability in determination of formaldehyde, and could be easily re-used over 80 h. The proposed flow microsensor was applied successfully in the determination of formaldehyde in artificial water samples and air.     

Determination of Gallic Acid by Flow Injection Analysis Based on Luminol‐AgNO3‐Ag NPs Chemiluminescence System

A novel flow injection procedure has been developed for the determination of gallic acid based on the enhancement function for luminol‐AgNO₃‐Ag NPs chemiluminescence (CL) system by gallic acid. The enhancement mechanism was proposed for the reinforcing effect of the gallic acid on the CL system. The UV‐vis absorption spectrum and CL emission spectrum were applied to confirm the mechanism. The method is simple, rapid and sensitive with a detection limit of 5×10^?10 g·mL^?1 and a linear range of 8.0×10^?10–1.0×10^?7 g·mL^?1. The relative standard deviation (RSD) is 1.3% for eleven measurements of 5×10^?8 g·mL^?1 gallic acid. The method has been successfully applied to the determination of gallic acid in Chinese proprietary medicine–Jianmin Yanhou tablets and synthesized samples.     

Luminol Chemiluminescence with Heteropoly Acids and its Application to the Determination of Arsenate,Germanate, Phosphate and Silicate by Ion Chromatography

A flow-injection chemiluminescence (CL) method has been proposed for sensitive determination of arsenate, germanate, phosphate and silicate, after separation by ion chromatography (IC). The post-column detection system involved formation of heteropoly acid in a H₂SO₄ medium before the CL reaction with luminol in an NaOH medium. For separation, heteropoly acid formation and the CL detection reaction, pH requirements were not compatible. When present as a heteropoly acid complex with molybdenum(VI), ger- manium(IV) and silicon(IV) caused CL emission from oxidation of luminol, and such a CL oxidation of luminol was observed analogously for arsenic(V) and phosphorus(V) but with the addition of metavanadate ion to the acid solution of molybdate. Good sensitivity for the three analytes arsenic(V), ger- manium(IV) and phosphorus(V) could be given by a single set of reagent conditions, chosen carefully. Another set was suitable for determining phosphorus(V) and silicon(IV). The minimum detectable concentrations of arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were 10, 50, 1 and 10 μg l⁻¹, respectively. Linear calibrations for arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were established over the respective concentration ranges of 10–1000, 50–25000, 1–1000 and 50–1 μg l⁻¹. The proposed IC–CL method was successfully applied to analyses of a seaweed reference material, rice wine and water samples.     

Highly sensitive chemiluminescence flow sensor for ascorbic acid

A highly sensitive chemiluminescence(CL) flow sensor is proposed for the determination of ascorbic acid. The analytical reagents luminol and iron(II) are immobilized on anion-exchange and cation-exchange resins, respectively, and can be eluted by sodium sulphate. The calibration graphs are linear in the range 1 × 10^–9 to 1 × 10^–6 g mL^–1 and the detection limit is 4.0 × 10^–10 g mL^–1. The sensor has been applied successfully to the determination of ascorbic acid in vegetables.     

Chemiluminescence determination of carbofuran at trace levels in lettuce and waters by flow-injection analysis

A simple, fast chemiluminescence (CL) flow-injection (FI) method based on the reaction of luminol with KMnO₄ in alkaline medium has been described for the direct determination of carbofuran. The method is based on the enhancing effect in the emission light from the oxidation of luminol produced in presence of carbofuran. The optimisation of instrumental and chemical variables influencing the CL response of the method has been carried out by applying experimental design, using the proposed flow-injection manifold. Under the optimal conditions, the CL intensity was linear for a carbofuran concentration over the range of 0.06-0.5 μg ml⁻¹, with a detection limit of 0.02 μg ml⁻¹. The method has been successfully applied to the determination of carbofuran residues in spiked water and lettuce samples.     

On‐line Liquid‐liquid Extraction Coupled to a Reversed Micellar‐mediated Chemiluminescence Detection System: Application to the Determination of Amino/Nitroaromatic Compounds

A simple and fast flow method for the trace level determination of p‐toluidine, 2‐methyl‐5‐nitroaniline, and 2,4‐dinitroaniline in aqueous samples is reported. These amino/nitroaromatics are related to trinitrotoluene (TNT) and appear during the degradation process of the explosive. The chemical principles of ion‐pair formation and liquid‐liquid extraction are applied: In aqueous acidic medium, the protonated analyte [HA]⁺ makes an ion‐pair with the tetrachloroaurate(III) ion, followed by on‐line ion‐pair extraction into the dichloromethane carrier used. After membrane separation, the CH₂Cl₂ containing the ion‐pair, [HA]⁺[AuCl₄]⁻, is mixed with the reversed micellar luminescent reagent of luminol (in 0.3 M Na₂CO₃) prepared from cetyl‐trimethylammonium chloride in CH₂Cl₂‐cyclohexane and the [AuCl₄⁻‐luminol chemiluminescence (CL) output is recorded. The detection limits (S/N> 3) are: p‐toluidine, 1.0 × 10⁻⁴M; 2‐methyl‐5‐nitroaniline, 1.0 × 10⁻⁷ M; 2,4‐dinitroaniline, 1.0 × 10⁻⁷ M, while the calibration curves are linear between 1.0 × 10⁻⁴ — 1.0 × 10⁻² M for all the compounds. Although spectral studies indicated the formation and extraction of a very small amount of the ion‐pair species, the reversed micellar‐mediated CL detection system provides an alternative procedure for the determination of degradation products of the explosive TNT in environmental aqueous samples.     

Simultaneous Determination of Epinephrine, Noradrenaline and Dopamine in Human Serum Samples by High Performance Liquid Chromatography with Chemiluminescence Detection

A simple, rapid and accurate high performance liquid chromatographic （HPLC） technique coupled with chemiluminescence （CL） detection was developed for the simultaneous determination of epinephrine （E）, noradrenaline （NA） and dopamine （DA）. It was based on the analyte enhancement effect on the CL reaction between luminol and potassium ferricyanide. The effects of various parameters, such as potassium ferricyanide concentration, luminol concentration, pH value and component of the mobile phase on chromatographic behaviors of the analytes （E, NA and DA） were investigated. The separation was carded out on C18 column using the mobile phase of 0.01 mol/L potassium hydrogen phthalate solution and methanol （92 ： 8, V/V）. Under the optimum condi- tions, E, NA and DA showed good linear relationships in the range of 1 × 10^-8 -5 × 10^-6, 5.0× 10^-9 -1.0× 10^-6 and 5.0×10^-9-1.0× 10^-6 g]mL respectively. The detection limits for E, NA and DA were 4.0×10^-9, 1.0× 10^-9 and 8.0 × 10^-10 g/mL. The proposed method has been applied successfully to the analysis of E, NA and DA in human serum samples.     

Chemiluminescence of Colloidal MnO2 with Luminol and Determination of Polyhydroxyl Compounds

The reaction between luminol and colloidal MnO₂ (prepared by chemical reduction of KMnO₄ with Na₂S₂O₃ under neutral aqueous condition) produced an intense chemiluminescence (CL) emission in alkaline medium. The CL reaction conditions were carefully optimized and the CL reaction mechanism was thoroughly discussed. Manganese(III) was suggested to be involved in the reaction and 3‐aminophthalate anion was the luminophor. Moreover, the effects of 23 compounds on the colloidal MnO₂‐luminol CL system were investigated to explore its possible analytical applications. Polyhydroxyl compounds were observed to inhibit the signal significantly, whereas sulfhydryl compounds enhance it slightly. The analytical figures for five polyhydroxyl compounds, namely ascorbic acid, rutin, pyrogallol, quercetin, and L‐adrenaline, were presented. As a preliminary application, the method was applied to the determination of rutin in pharmaceutical formulations.