Chemiluminescence detection of trace iodide with flow injection analysis of KMnO4‐carbon dots system

Ultra‐weak chemiluminescence (CL) from the reaction of iodide and KMnO₄ was strongly enhanced by carbon nanodots (CNDs) in an acidic medium. The CL intensity was directly proportional to the concentration of iodide in the solution. Therefore, a flow‐injection CL system with high sensitivity, selectivity and reproducibility is proposed for the determination of iodide. The proposed method exhibited advantages over a linear range of 3.0 × 10^?6–1.0 × 10^?4 mol/L and had a detection limit of 3.5 × 10^?7 mol/L. The method was successfully applied to the evaluation of iodide in food samples with recoveries of between 96 and 103%. The relative standard deviations were 2.1 and 4.1% for intra‐ and inter‐assay precision, respectively.     

Multiway analysis applied to time‐resolved chemiluminescence for simultaneous determination of paracetamol and codeine in pharmaceuticals

This method is based on the enhancing effect of codeine (COD) and paracetamol (PAR) on the chemiluminescence (CL) reaction of Ru(phen)₃²⁺ with Ce(IV). In the batch mode, COD gives a relatively sharp peak with the highest CL intensity at 4.0 s, whereas the maximum CL intensity of the PAR appears at ~60 s after injection of Ce(IV) solution. Whole CL time profiles allowed use of the time‐resolved CL data in combination with multiway calibration techniques, as multiway partial least squares (N‐PLS), for the quantitative determination of both COD and PAR in binary mixtures. In this work, we found that the impact of Ce(IV) concentration on the CL intensity was different for COD and PAR. Therefore, a Ce(IV) concentration mode was added to the time and sample modes to obtain 3D data. The percent relative standard deviation (%RSD) values for 10 determinations of 1.0 × 10^?5 mol/L of COD and 1.0 × 10^?4 mol/L of PAR were 6.1% and 8.7%, respectively. The limit of detection (LOD) values (S/N = 3) were 0.9 × 10^?8 mol/L and 1.0 × 10^?6 mol/L for COD and PAR, respectively. The proposed method was successfully applied to the determination of PAR and COD in commercial pharmaceutical formulations. Acceptable recoveries (90–110%) were obtained for the quantification of these drugs in the real samples. Copyright © 2016 John Wiley & Sons, Ltd.     

Sensitive determination of epinephrine in pharmaceutical preparation by flow injection coupled with chemiluminescence detection and mechanism study

A novel, rapid and sensitive method was described for the determination of epinephrine (EP) using flow injection analysis coupled with chemiluminescence (CL) detection, which based on EP enhanced the weak CL emission of luminol–KIO₄ system in NaOH solution. Parameters affecting the CL intensity and reproducibility were optimized systematically. Under the optimized experiment conditions, the net CL intensity was proportional to the concentration of EP in the range of 5.0 × 10^?8 to 1.5 × 10^?6 mol/L with a detection limit of 1.9 × 10^?9 mol/L. The relative standard deviation (RSD) was found to be 0.7% for 13 replicate determinations of 3.0 × 10^?7 mol/L EP. The applicability of the proposed method was illustrated in the determination of EP in pharmaceutical preparation. The recoveries of EP at different levels in EP hydrochloride injection were between 95.4 and 104.7%. One assay procedure takes only 27 s, and the sampling rate was calculated about to be 130 samples/h. The possible mechanism of the enhanced CL intensity was studied by examining CL spectra and UV–vis spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

The determination of glutamine with flow‐injection chemiluminescence detection and mechanism study

The main purpose of this study was to develop an inexpensive, simple, rapid and sensitive chemiluminescence (CL) method for the determination of glutamine (Gln) using a flow‐injection (FI) system. Gln was found to strongly inhibit the CL signal of the luminol–H₂O₂–CuSO₄ system in Na₂B₄O₇ solution. A new FI‐CL method was developed for the determination of Gln. Parameters affecting the reproducibility and CL detection were optimized systematically. Under the optimized conditions, the corresponding linear regression equation was established over the range of 5.0 × 10^?7 to 2.5 × 10^?6 mol/L with the detection limit of 1.8 × 10^?8 mol/L. The relative standard deviation was found to be 1.8% for 11 replicate determinations of 1.5 × 10^?6 mol/L Gln. The proposed method has been satisfactorily applied for the determination of Gln in real samples (Marzulene‐s granules) with recoveries in the range of 98.7–108.6%. The minimum sampling rate was about 100 samples/h. The possible mechanism of this inhibitory CL was studied by fluorescence spectrophotometer and UV–vis spectrophotometer. Copyright © 2009 John Wiley & Sons, Ltd.     

DPPH·–luminol chemiluminescence system and its application in the determination of scutellarin in pharmaceutical injections and rat plasma with flow injection analysis

In this article, a DPPH·–luminol chemiluminescence (CL) system was reported and the CL mechanism was discussed according to the CL kinetic properties after sequence injecting DPPH· into the DPPH·–luminol reaction mixture. It was observed that scutellarin could inhibit the CL response of the DPPH·–luminol system. Based on this observation, a simple and rapid flow injection CL method was developed for the determination of scutellarin using the inhibition effect in alkaline medium. The optimized chemical conditions for the CL reaction were 5 × 10^?6 mol/L DPPH · and 1.0 × 10^?4 mol/L luminol in 0.01 mol/L NaOH. Under optimized conditions, the CL intensity was inversely proportional to the concentration of scutellarin over the ranges 5–2000 and 40–3200 ng/ml in pharmaceutical injection and rat plasma, respectively. The limits of detection (S/N  = 3) were 5 and 40 ng/ml in preparations and rat plasma, respectively. Furthermore, the precision, recovery and stability of the validated method were acceptable for the determination of scutellarin in both pharmaceutical injections and rat plasma. The presented method was successfully applied in the determination of scutellarin in pharmaceutical injections and real rat plasma samples.     

Resonance light‐scattering enhancement effect of the protein–Y3+–TTA–SLS system and its analytical application

In this paper, a sensitive resonance light scattering (RLS) method for the determination of protein is reported. In the Tris–HCl (pH 7.50) buffer, protein enhanced the RLS intensity of the Y³⁺–2‐thenoyltrifluoroacetone (TTA)–sodium dodecyl sulphate (SLS) system. The enhanced RLS intensities were in proportion to the concentrations of proteins in the range 8.0 × 10^?9–1.0 × 10^?5 g/mL for BSA, 1.0 × 10^–8–1.0 × 10^?5 g/mL for HSA and 1.0 × 10^–8–1.0 × 10^?6 g/mL for EA, and their detection limits were 5.0, 5.4 and 6.7 ng/mL, respectively. Actual samples were satisfactorily determined. The interaction mechanism was also studied. Copyright © 2008 John Wiley & Sons, Ltd.     

A selective and sensitive fluorescent sensor for cysteine detection based on bi‐8‐carboxamidoquinoline derivative and Cu2+ complex

In this paper, a novel fluorescent sensor 1 for selective and sensitive detection of cysteine was developed based on a complex between bi‐8‐carboxamidoquinoline derivative ligand ( L ) and Cu²⁺. The interaction of Cu²⁺ with the ligand causes a dramatic fluorescence quenching most likely due to its high affinity towards Cu²⁺ and a ligand–metal charge transfer (LMCT) process. The in situ generated L–Cu ² complex was utilized as a chemosensing ensemble for cysteine. In the presence of cysteine, the fluorophore, L , was released from L–Cu ² complex because of the strong affinity of cysteine to Cu²⁺ via the Cu–S bond, leading to the fluorescence recovery of the ligand. The proposed displacement mechanism was confirmed by the results of mass spectrometry (MS) study. Under optimized conditions, the recovered fluorescence intensity is linear with cysteine concentrations in the range 1 × 10^?6 mol/l to 8 × 10^?6 mol/l. The detection limit for cysteine is 1.92 × 10^?7 mol/l. Furthermore, the established method showed a highly sensitive and selective response to cysteine among the 20 fundamental α‐amino acids used as the building blocks of proteins, after Ni²⁺ was used as a masking agent to eliminate the interference of His. The proposed sensor is applicable in monitoring cysteine in practical samples with good recovery rate.     

New luminol chemiluminescence reaction using diperiodatoargentate as oxidate for the determination of amikacin sulfate

A new chemiluminescence (CL) reaction between luminol and diperiodatoargentate {K₂ [Ag (H₂IO₆) (OH) ₂]} was observed in alkaline medium. The CL intensity could be greatly enhanced by amikacin sulfate. Therefore a new CL method for the determination of amikacin sulfate was built by combining with flow injection technology. A possible mechanism of the CL reaction was proposed via the investigation of the CL kinetic characteristics, the CL spectrum and the UV absorption spectra of some related substance. The concentration range of linear response was 5.1 × 10^?8 to 5.1 × 10^?6 mol L^?1 with a detection limit of 1.9 × 10^?8 mol L^?1 (3σ). The proposed method had good reproducibility with a relative standard deviation of 2.8% (n = 7) for 5.1 × 10^?7 mol L^?1 of amikacin sulfate. It was successfully applied to determine amikacin sulfate in serum. Copyright © 2009 John Wiley & Sons, Ltd.     

Flow‐injection determination of vitamin A in pharmaceutical formulations using Tris(2,2′‐bipyridyl)Ru(II)–Ce(IV) chemiluminescence detection

A flow injection method with chemiluminescence detection is reported for the determination of vitamin A. The method is based on the enhancement effect of vitamin A on chemiluminescence of tris(2,2′‐bipyridyl)Ru(II)–Ce(IV) in acidic medium. The proposed procedure is used to quantitate vitamin A in the range 1.0–100 × 10^?6 mol/L with a correlation coefficient of 0.9991 (n = 9) and relative standard deviation in the range 1.2–2.3% (n = 4). The limit of detection (3 × blank) was 8.0 × 10^?8 mol/L with a sample throughput of 100/h. The effect of common excipients used in pharmaceutical formulations and some clinically important compounds was also studied. The method was applied to determine vitamin A in pharmaceutical formulations and the results obtained were in reasonable agreement with the amount quoted. The results were compared using spectrophotometric method and no significant difference was found between the results of the two methods at 95% confidence limit. Copyright © 2009 John Wiley & Sons, Ltd.     

Flow injection–chemiluminescence determination of amoxycillin using potassium permanganate and formaldehyde system

It was found that amoxycillin can react with potassium permanganate in an acidic medium to produce chemiluminescence, which is greatly enhanced by formaldehyde. The optimum conditions for this chemiluminescent reaction were studied in detail using a flow‐injection system. The experimental results indicate that, under optimum conditions, the chemiluminescence intensity is linearly related to the concentration of amoxycillin in the range 5.48 × 10^?8–2.74 × 10^?6 mol[sol ]L, with a detection limit (3σ) of 4.1 × 10^?8 mol[sol ]L. The relative standard deviation was 1.0% at 1.1 × 10^?6 mol[sol ]L amoxycillin (n = 11 measurements). This method has the advantages of high sensitivity, fast response and ease of operation. The method was successfully applied to the determination of amoxycillin in raw medicines and capsules. Copyright © 2005 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence method for the determination of naphazoline hydrochloride and oxymetazoline hydrochloride

A sensitive and simple flow‐injection chemiluminescence (FI‐CL) method, which was based on the CL intensity generated from the redoxreaction of potassium permanganate (KMnO₄)–formaldehyde in vitriol (H₂SO₄) medium, has been developed, validated and applied for the determination of naphazoline hydrochloride and oxymetazoline hydrochloride. Besides oxidants and sensitizers, the effect of the concentration of H₂SO₄, KMnO₄ and formaldehyde was investigated. Under the optimum conditions, the linear range was 1.0 × 10^?2–7.0 mg/L for naphazoline hydrochloride and 5.0 × 10^?2–10.0 mg/L for oxymetazoline hydrochloride. During seven repeated inter‐day and intra‐day precision tests of 0.1, 1.0 and 10.0 mg/L samples, the relative standard deviations all corresponded to reference values. The detection limit was 8.69 × 10^?3 mg/L for naphazoline hydrochloride and 3.47 × 10^?2 mg/L for oxymetazoline hydrochloride (signal‐to‐noise ratio ≤3). This method has been successfully implemented for the determination of naphazoline hydrochloride and oxymetazoline hydrochloride in pharmaceuticals. Copyright © 2009 John Wiley & Sons, Ltd.     

Fluorescence sensing of nitric oxide in aqueous solution by triethanolamine‐modified CdSe quantum dots

The water‐soluble luminescent CdSe quantum dots were prepared by ligand exchange with triethanolamine (TEA). Oxygen can reversibly enhance the fluorescence of the synthesized quantum dots (TEA‐CdSe‐QDs) in aqueous solution. Nitric oxide radical (NO) can react easily with dissolved oxygen in water and was found to have a significant quenching effect on the fluorescence of the TEA‐CdSe‐QDs. The fluorescence responses were concentration‐dependent and can be well described by the typical Stern–Volmer equation. A good linear relationship (R² = 0.9963) was observed over the range 5.92 × 10^?7 to 1.85 × 10^?5 mol/L nitric oxide. Above this concentration was a second linear region ranging from 2.12 × 10^?5 to 1.12 × 10^?4 mol/L NO with a gentler slope. The detection limit, calculated following the 3σ IUPAC criteria, was 3.02 × 10^?7 mol/L. The interference effect of some common interferents such as nitrite (NO₂^?), nitrate (NO₃^?), glucose and l ‐ascorbic acid on the detection of NO was negligible for the proposed system, demonstrating the potential utility of this probe for the detection of NO in biological systems. The possible mechanism was also discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Rapid determination of gatifloxacin in biological samples and pharmaceutical products using europium‐sensitized fluorescence spectrophotometry

A europium‐sensitized fluorescence spectrophotometry method using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS), was developed for the determination of gatifloxacin (GFLX). The GFLX–Eu³⁺–SDBS system was studied and it was found that SDBS significantly enhanced the fluorescence intensity of the GFLX–Eu³⁺ complex (about 25‐fold). The optimal experimental conditions were determined as follows: excitation and emission wavelengths of 338 and 617 nm, pH 7.5, 3.0 × 10^–6 mol/L europium(III), and 5.0 × 10^–5 mol/L SDBS. The enhanced fluorescence intensity of the system (ΔI_f) showed a good linear relationship with the concentration of GFLX over the range 1.0 × 10^–8–8.0 × 10^–7 mol/L with a correlation coefficient of 0.9990. The detection limit (S:N = 3) was determined as 1.0 × 10^–9 mol/L. This method has been successfully applied for the determination of GFLX in pharmaceuticals and human urine/serum samples. Compared with most other methods reported, the rapid and simple procedure proposed here offered higher sensitivity, wider linear range and good stability. The luminescence mechanism of the system is also discussed in detail. Copyright © 2008 John Wiley & Sons, Ltd.     

The behaviors of metal ions in the CdTe quantum dots–H2O2 chemiluminescence reaction and its sensing application

The behaviors of 15 kinds of metal ions in the thiol‐capped CdTe quantum dots (QDs)–H₂O₂ chemiluminescence (CL) reaction were investigated in detail. The results showed that Ag⁺, Cu²⁺ and Hg²⁺ could inhibit CdTe QDs and H₂O₂ CL reaction. A novel CL method for the selective determination of Ag⁺, Cu²⁺ and Hg²⁺ was developed, based on their inhibition of the reaction of CdTe QDs and H₂O₂. Under the optimal conditions, good linear relationships were realized between the CL intensity and the logarithm of concentrations of Ag⁺, Cu²⁺ and Hg²⁺. The linear ranges were from 2.0 × 10^?6 to 5.0 × 10^?8 mol L^?1 for Ag⁺, from 5.0 × 10^?6 to 7.0 × 10^?8 mol L^?1 for Cu²⁺ and from 2.0 × 10^?5 to 1.0 × 10^?7 mol L^?1 for Hg²⁺, respectively. The limits of detection (S/N = 3) were 3.0 × 10^?8, 4.0 × 10^?8 and 6.7 × 10^?8 mol L^?1 for Ag⁺, Cu²⁺ and Hg²⁺, respectively. A possible mechanism for the inhibition of CdTe QDs and H₂O₂ CL reaction was also discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Highly sensitive spectrofluorimetric determination of trace amounts of prulifloxacin using the aluminium(III)–prulifloxacin system

The fluorescence of the prulifloxacin (PUFX)–Al(III) system was investigated . Experiments indicated that the fluorescence intensity of prulifloxacin could be greatly enhanced by Al(III) and sensitized by sodium dodecylbenzene sulphonate (SDBS). Accordingly, a sensitive spectrofluorimetric method for the determination of prulifloxacin was established. While excited at 275 nm, the enhanced fluorescence intensity at 412 nm of the system (ΔF) showed a good linear relationship with the concentration of prulifloxacin within the range 4.0 × 10^–8–3.0 × 10^–6 mol/L. The regression equation was ΔF = 9.83 + 10.8 × 10⁷c (mol/L); the correlation coefficient and detection limit (3σ/k) were 0.99901 and 2.0 × 10^–8 mol/L, respectively. The proposed method has been successfully applied to determine prulifloxacin in real pharmaceutical samples. The luminescence mechanism of the system is also discussed in detail. Copyright © 2008 John Wiley & Sons, Ltd.     

Electrophoresis–chemiluminescence detection of phenols catalyzed by hemin

Based on the catalytic activity of hemin, an efficient biocatalyst, an indirect capillary electrophoresis–chemiluminescence (CE‐CL) detection method for phenols using a hemin–luminol–hydrogen peroxide system was developed. Through a series of static injection experiments, hemin was found to perform best in a neutral solution rather than an acidic or alkaline medium. Although halide ions such as Br^? and F^? could further enhance the CL signal catalyzed by hemin, it is difficult to apply these conditions to this CE‐CL detection system because of the self‐polymerization of hemin, as it hinders the CE process. The addition of concentrated ammonium hydroxide to an aqueous/dimethyl sulfoxide solution of hemin–luminol afforded a stable CE‐CL baseline. The indirect CE‐CL detection of five phenols using this method gave the following limits of detections: 4.8 × 10^?8 mol/L (o‐sec‐butylphenol), 4.9 × 10^?8 mol/L (o‐cresol), 5.4 × 10^?8 mol/L (m‐cresol), 5.3 × 10^?8 mol/L (2,4‐dichlorophenol) and 7.1 × 10^?8 mol/L (phenol). Copyright © 2013 John Wiley & Sons, Ltd.     

Chiral determination of cinchonine using an electrochemiluminescent sensor with molecularly imprinted membrane on the surfaces of magnetic particles

A novel molecular imprinting electrochemiluminescence sensor for detecting chiral cinchonine molecules was developed with a molecularly imprinted polymer membrane on the surfaces of magnetic microspheres. Fe₃O₄@Au nanoparticles modified with 6‐mercapto‐beta‐cyclodextrin were used as a carrier, cinchonine as a template molecule, methacrylic acid as a functional monomer and N ,N ′‐methylenebisacrylamide as a cross‐linking agent. Cinchonine was specifically recognized by the 6‐mercapto‐beta‐cyclodextrin functional molecularly imprinted polymer and detected based on enhancement of the electrochemiluminescence intensity caused by the reaction of tertiary amino structures of cinchonine molecules with Ru(bpy)₃²⁺. Cinchonine concentrations of 1 × 10^?10 to 4 × 10^?7 mol/L showed a good linear relationship with changes of the electrochemiluminescence intensity, and the detection limit of the sensor was 3.13 × 10^?11 mol/L. The sensor has high sensitivity and selectivity, and is easy to renew. It was designed for detecting serum samples, with recovery rates of 98.2% to 107.6%.     

Post‐chemiluminescence determination of chloramphenicol based on luminol–potassium periodate system

A post‐chemiluminescence (PCL) phenomenon was observed when chloramphenicol was injected into a mixture of luminol and potassium periodate after the chemiluminescence (CL) reaction of luminol–potassium periodate had finished. The possible reaction mechanism was proposed based on studies of the CL kinetic characteristics, the CL spectra, the fluorescence spectra and the UV‐vis absorption spectra of the related substances. Based on the PCL reaction, a rapid and sensitive method for the determination of chloramphenicol was established. The linear response range was 6.0 × 10^?7–1.0 × 10^?5 mol/L, with a correlation coefficient of 0.9986. The relative standard deviation (RSD) for 5.0 × 10^?6 mol/L chloramphenicol was 2.3% (n = 11). The detection limit was 1.6 × 10^?7 mol/L. The method has been applied to the determination of chloramphenicol in pharmaceutical samples with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.     

Increasing copper alters cellular elemental composition (Mo and P) of marine diatom

The elemental composition (surface adsorbed and internalized fraction of Cu, Mo and P) in marine phytoplankton was first examined in cultures of the diatom Phaeodactylum tricornutum which were exposed to various levels of Cu concentrations ranging from 0.25 to 16 μmol/L with equivalent free [Cu²⁺] concentrations of 0.4–26 nmol/L. We observed an acceleration of algal growth rates (20–40%) with increasing ambient Cu levels, as well as slightly increased levels of internalized Cu in cells (2–13 × 10^?18 mol/cell) although cellular Cu mostly accumulated onto the cell surface (>50% of the total: intracellular + surface adsorbed). In particular, we documented for the first time that the elemental composition (Mo and P) in algal cells varies dynamically in response to increased Cu levels: (1) Cellular P, predominantly in the intracellular compartment (>95%), shows with a net consumption as indicated by a gradual decrease with increasing [Cu²⁺] (120→50 × 10^?15 mol P/cell) probably due to the fact that P, a backbone bioelement, is largely required in forming biological compartments such as cell membranes; and (2) cellular Mo, predominantly encountered in the intracellular compartment, showed up to tenfold increase in concentration in the cultures exposed to Cu, with a peak accumulation of 1.1 × 10^?18 mol Mo/cell occurring in the culture exposed to [Cu²⁺] at 3.7 nmol/L. Such a net cellular Mo accumulation suggests that Mo might be specifically required in biological processes, probably playing a counteracting role against Cu.     

A novel chemiluminescent flow injection analysis of trace amounts of rutin by its inhibition of the luminol–hydrogen peroxide reaction catalyzed by tetrasulfonated colbalt phthalocyanine

Based on the inhibition effect of rutin on the luminol–hydrogen peroxide chemiluminescence (CL) system catalyzed by tetrasulfonated colbalt phthalocyanine (CoTSPc), a sensitive flow‐injection CL method has been developed for the determination of rutin. The CL reaction mechanism was carefully investigated by examining CL emission spectra, UV–visible spectra and variation of reaction conditions. It was found that there existed a linear relationship between CL intensity and the concentration of rutin in the range of 8.0 × 10^?9 to 1.0 × 10^?6 mol L^?1, and the detection limit is 3.8 × 10^?9 mol L^?1. This proposed method is sensitive, convenient and simple, and has been applied to the determination of rutin in commercial rutin tablets with satisfactory results. Copyright © 2009 John Wiley & Sons, Ltd.