Post-chemiluminescence behaviour of Ni2+, Mg2+, Cd2+ and Zn2+ in the potassium ferricyanide-luminol reaction.

A new chemiluminescence (CL) reaction was observed when Ni2+, Mg2+, Cd2+ or Zn2+ was injected into the reaction mixture after the finish of the CL reaction of alkaline luminol and potassium ferricyanide. This reaction is described as a post-chemiluminescence (PCL) reaction. The possible mechanism for the PCL was proposed based on studies of the CL kinetic characteristic and the CL spectra. The experimental conditions of the CL reactions were optimized and the feasibility of using the reaction to analyse these metal ions was evaluated. The PCL reaction method operates in the ranges: 1 x 10(-7)-8 x 10(-6) g/L Ni2+; 3 x 10(-6)-2 x 10(-4) g/L Mg2+; 8 x 10(-7)-1 x 10(-4) g/L Cd2+; and 2 x 10(-4)-2 x 10(-3) g/L Zn2+, with detection limits of 4 x 10(-8) g/mL, 1 x 10(-6) g/mL, 3 x 10(-7) g/mL, 8 x 10(-5) g/mL, respectively.     

Chemiluminescence determination of fluoroquinolone antibiotics using a soluble manganese (IV)-sulphite system.

The reaction of soluble manganese (IV) with sulphite in acidic condition was found to elicit weak chemiluminescence (CL). The CL signal was remarkably enhanced in the presence of three fluoroquinolones, viz. norfloxacin, ofloxacin and ciprofloxacin. Based on these observations, a new flow-injection CL method was developed for the determination of these fluoroquinolones. The method allows determination in the range 5.0 x 10(-8)-1.0 x 10(-6) mol/L for norfloxacin, 1.0 x 10(-7)-8.0 x 10(-6) mol/L for ofloxacin and 1.0 x 10(-7)-3.0 x 10(-5) mol/L for ciprofloxacin, with detection limits of 3 x 10(-8) mol/L, 5 x 10(-8) mol/L and 3 x 10(-8) mol/L, respectively. The method was applied to the determination of fluoroquinolones in pharmaceutical preparations.     

Flow-injection determination of streptomycin residues in milk using the luminol-periodate-Mn2+ chemiluminescence system.

A novel flow-injection method with chemiluminescence detection was developed for the determination of streptomycin residues in milk, based on the enhancement by streptomycin of the luminol-potassium periodate-Mn(2+) chemiluminescence system. The assay allowed analysis of streptomycin residues in whole milk samples ( approximately 3.5% fat) after sample work-up procedures. The limit of detection was 5.16 x 10(-9) mol/L for milk, and was far below the regulations of maximum residue limits (MRLs). The relative standard deviation (RSD) for 8.66 x 10(-8) mol/L streptomycin was 1.94% (n = 15) in milk. The results obtained for the assay of streptomycin residues in milk was comparable with those obtained by the official methods (ELISA) and demonstrated good accuracy and precision. The possible mechanism is briefly discussed.     

Flow-injection chemiluminescence determination of catecholamines based on their enhancing effects on the luminol-potassium periodate system.

A rapid and sensitive chemiluminescence (CL) method using flow injection analysis is described for the determination of four catecholamines, dopamine, adrenaline, isoprenaline and noradrenaline, based on their greatly enhancing effects on the CL reaction of luminol-potassium periodate in basic solutions. The optimized chemical conditions for the chemiluminescence reaction were 1.0 x 10(-4) mol/L luminol and 1.0 x 10(-5) mol/L potassium periodate in 0.2 mol/L sodium hydroxide (NaOH). Under the optimized conditions, the calibration graphs relating the CL signal intensity (peak height) to the concentration of the analytes were curvilinear and they were suitable for determining dopamine, adrenaline, isoprenaline, and noradrenaline in the range 0.1-10 ng/mL, 0.1-100 ng/mL, 1-100 ng/mL and 5-50 ng/mL, respectively, with the relative standard deviations of 0.8-1.7%. The detection limits of the method are 0.02 ng/mL for dopamine, 0.01 ng/mL for adrenaline, 0.1 ng/mL for isoprenaline and 2.0 ng/mL for noradrenaline. The sampling frequency was calculated to be about 60/h. The selectivity of the method was good, because a series of common ions or excipients, such as K(+), Ba(2+), CO(3)(2-), NO(3)(-), SO(4)(2-), PO(4)(3-), sodium citrate, sodium bisulphite, oxidate dopamine, starch, lactose, carbamide and gelatin, could not produce interference when their concentrations were 1000-fold than those of dopamine. The present method was successfully applied to the determination of the four catecholamines in pharmaceutical injections.     

Determination of tetracycline, chlortetracycline and oxytetracycline by flow injection with inhibitory chemiluminescence detection using copper(II) as a probe ion.

This paper reports an indirect flow-injection (FI) method for the determination of the tetracycline drugs (TCs), tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC), using copper(II) as a probe ion. The method was based on the inhibition caused by these TCs to the copper(II)-catalysed chemiluminescence (CL) reaction between luminol and H(2)O(2). The CL reaction was induced on-line and injection of the sample produced negative peaks as a result of the copper(II) complexation or displacement by the analytes. The height of the peaks was proportional to the drug concentration in the sample. The choice of the catalyst ion, the concentration of luminol, H(2)O(2) and copper(II) are discussed. The linear range was 3.6 x 10(-8)-1.0 x 10(-5), 1.1 x 10(-7)-1.0 x 10(-5) and 1.9 x 10(-7)-1.0 x 10(-5) mol/L for TC, CTC and OTC, respectively. The detection limit was 5.0 x 10(-9) mol/L for TC, 1.0 x 10(-8) mol/L for CTC and 2.0 x 10(-8) mol/L for OTC (3sigma), respectively. The method was applied to the determination of TCs in pharmaceutical preparations and human urine with recoveries in the range 95-105%.     

Flow-injection electrogenerated chemiluminescence determination of fluoroquinolones based on its sensitizing effect.

A simple and sensitive flow-injection electrogenerated chemiluminescence (ECL) method for the determination of fluoroquinolones was developed. The method is based on the sensitizing effect of fluoroquinolones on the weak ECL signal of electrochemical oxidation of luminol on the surface of the platinum flake electrode in the medium of 0.1 mol/L Na2CO3-NaHCO3. At the optimum experimental conditions, the relative ECL intensity increased linearly with increasing fluoroquinolones concentration, in the ranges 1.0 x 10(-8)-2.0 x 10(-4) g/mL for norfloxacin, 5.0 x 10(-9)-6.0 x 10(-6) g/mL for oxfloxacin, 2.0 x 10(-8)-1.4 x 10(-5) g/mL for ciprofloxacin, 1.0 x 10(-8)-1.4 x 10(-5) g/mL for pefloxacin, and 1.0 x 10(-9)-1.0 x 10(-5) g/mL for enoxacin, with detection limits of 4.0 x 10(-9) g/mL, 2.0 x 10(-9) g/mL, 1.0 x 10(-8) g/mL, 8.0 x 10(-9) g/mL, and 8.0 x 10(-10) g/mL, respectively. The relative standard deviations were all less than 2.5% for the determination of 2.0 x 10(-6) g/mL fluoroquinolones (n = 11). The method was used to determine these medicines in pharmaceutical samples with satisfactory results.     

Kinetics and mechanisms of the recombination of Zn2+, Co2+, and Ni2+ with the metal-depleted catalytic site of horse liver alcohol dehydrogenase

The kinetics of the recombination of the metal-depleted active site of horse liver alcohol dehydrogenase (LADH) with metal ions have been studied over a range of pH and temperature. The formation rates were determined optically, by activity measurements, or by using the pH change during metal incorporation with a pH-indicator as monitor. The binding of Zn2+, Co2+, and Ni2+ ions occurs in a two-step process. The first step is a fast equilibrium reaction, characterized by an equilibrium constant K1. The spectroscopic and catalytic properties of the native or metal-substituted protein are recovered in a slow, monomolecular process with the rate constant k2. The rate constants k2 5.2 X 10(-2) sec-1 (Zn2+), 1.1 X 10(-3) sec-1 (Co2+), and 2 X 10(-4) sec-1 (Ni2+). The rate constants increase with increasing pH. Using temperature dependence, the activation parameters for the reaction with Co2+ and Ni2+ were determined. Activation energies of 51 +/- 2.5 kJ/mol (0.033 M N-Tris-(hydroxymethyl)methyl-2-aminomethane sulfonic acid (TES), pH 6, 9) for Co2+ and 48.5 +/- 4 kJ/mol (0.033 M TES, pH 7, 2) for Ni2+ at 23 degrees C were found. The correspondent activation entropies are - 146 +/- 10 kJ/mol K for Co2+ and - 163 +/- 9 kJ/mol K for Ni2+. Two protons are released during the binding of Zn2+ to H4Zn(n)2 LADH in the pH range 6.8-8.1. The binding of coenzyme, either reduced or oxidized, prevents completely the incorporation of metal ions, suggesting that the metal ions enter the catalytic site via the coenzyme binding domain and not through the hydrophobic substrate channel.     

High-sensitive determination of coenzyme Q(10) in iodinate-beta-cyclodextrin medium by inclusion reaction and catalytic polarography

A novel polarographic method for the determination of coenzyme Q(10) in beta-cyclodextrin (beta-CD) and iodinate system is proposed. The stability of coenzyme Q(10) to light was improved by the formation of coenzyme Q(10)-beta-CD inclusion complex. In addition, the sensitivity for the determination of coenzyme Q(10) was enhanced by both the formation and the polarographic catalytic wave of the inclusion complex in the presence of iodinate. In 0.1 mol/L HAc-NaAc (pH 4.7)-5.0 x 10(-5) mol/L beta-CD-1.2 x 10(-3) mol/L potassium iodinate-ethanol/water (60:40, v/v) medium, coenzyme Q(10)-beta-CD inclusion complex yielded a sensitive association/parallel catalytic wave. The second-order derivative peak current of the catalytic wave was proportional to coenzyme Q(10) concentration in the range of 6.0 x 10(-8)-2.5 x 10(-7) mol/L, and the detection limit was 1.0 x 10(-8) mol/L. The proposed method has high analytical sensitivity and is allowed to determine coenzyme Q(10) under light.     

Use of molecule imprinting-chemiluminescence method for the determination of tamoxifen in breast cancer sufferers' urine.

The reaction between soluble Mn(IV) and tamoxifen can produce chemiluminescence and formaldehyde can enhance this chemiluminescence reaction. A tamoxifen molecular imprinted polymer (MIP) was synthesized and its adsorption selectivity to tamoxifen in aqueous solution was evaluated. Using a synthesized tamoxifen MIP as the recognition material and a soluble Mn(IV)-formaldehyde-tamoxifen chemiluminesence system as the detection system, a new molecule imprinting-chemiluminesence method of determination of tamoxifen was established. The response range of this method was 1.0 x 10(-7)-6.0 x 10(-6) g/mL, with a linear correlation coefficient of 0.997. The detection limit was 4 x 10(-8) g/mL. The relative standard deviation for 5.0 x 10(-7) g/mL tamoxifen solution was 4.1% (n = 9).     

A sensitive inhibition chemiluminescence method for the determination of trace tannic acid using the reaction of luminol-hydrogen peroxide catalysed by tetrasulphonated manganese phthalocyanine.

A novel CL method for the determination of tannic acid (TA) was established based on TA inhibition of the chemiluminescence (CL) emission of the luminol-hydrogen peroxide CL system catalysed by tetrasulphonated manganese phthalocyanine (MnTSPc) under alkaline conditions. The peak height is proportional to the natural logarithm of concentration of TA in the range 1.0 x 10(-7)-3.0 x 10(-10) mol/L with a detection limit of 5.6 x 10(-11) mol/L and the relative standard deviation was 2.5% for the determination of 1.0 x 10(-8) mol/L TA (n = 11). The proposed method has been successfully applied to the determination of TA in Chinese gall and industrial wastewater.     

An assay for inorganic mercury(II) based on its post-catalytic enhancement effect on the potassium permanganate-luminol system.

A strong chemiluminescence (CL) response is observed when potassium permanganate solution is injected into basic luminol solution. When the CL reaction terminates, subsequent injection of Hg2+ solution into the reaction mixture results in a new CL reaction. Based on the post-catalytic enhancement effect of Hg2+ on the potassium permanganate-luminol system in basic media, a fast and simple CL-coupled flow injection analysis for the determination of Hg2+ was developed. In optimum conditions, CL intensity is proportional to Hg2+ concentration over the range 1.0 x 10(-8)-1.0 x 10(-5) g/mL, with a detection limit of 2.0 x 10(-9) g/mL. The relative standard deviation (RSD) is 3.6% for 1.0 x 10(-7) g/mL Hg2+ (n = 11). After pretreatment with sulphydryl cotton fibre, environmental water samples were analysed by the proposed method for total mercury determination with satisfactory results. The results were in good agreement with those given by hydride generation-cold vapour atomic absorption spectrometry (HG-CVAAS).     

A new sensitive flow-injection chemiluminescence method for the determination of H(2)-receptor antagonists.

Based on the chemiluminescence (CL) intensity generated from the potassium ferricyanide [K(3)Fe(CN)(6)]-rhodamine 6G system in sodium hydroxide (NaOH) medium, a new sensitive flow-injection chemiluminescence (FI-CL) method has been developed, validated and applied for the determination of three kinds of H(2)-receptor antagonists: cimetidine (CIMT), ranitidine (RANT) hydrochloride and famotidine (FAMT). Under the optimum conditions, the linear range for the determination was 1.0 x 10(-9)-7.0 x 10(-5) g/ml for CIMT, 1.0 x 10(-9)-5.0 x 10(-5) g/mL for RANT hydrochloride and 5.0 x 10(-9)-7.0 x 10(-5) g/mL for FAMT. During 11 repeated measurements of 1.0 x 10(-6) g/mL sample solutions, the relative standard deviations (RSDs) were all <5%. The detection limit was 8.56 x 10(-10) g/mL for CIMT, 8.69 x 10(-10) g/mL for RANT hydrochloride and 2.35 x 10(-9) g/mL for FAMT (S:N = 3). This method has been successfully implemented for the analysis of H(2)-receptor antagonists in pharmaceuticals.     

DNA‐based chemiluminescent nanoprobes for highly sensitive and selective detection of mercury(II) ion

A simple and sensitive DNA‐stablized gold nanoparticle (AuNP)‐based chemiluminescent (CL) probe for detecting mercury ion (Hg²⁺) in aqueous solution has been developed. The CL strategy relies upon the catalytic activity of unmodified AuNPs on the luminol–H₂O₂ CL reaction, and the interaction of unmodified AuNPs with DNA. The unmodified AuNPs can effectively differentiate unstructured and folded DNA. The DNA desorbs from AuNPs in the presence of Hg²⁺, leading to the increase in CL signal. By rationally varying the number of thymine in single‐strand oligonucleotides, the detection range could be tuned. Employing single‐strand oligonucleotides with 14 thymine in the detecting system, a sensitive linear range for Hg²⁺ ions from 5.0 × 10^–10 to 1.0 × 10^–7 mol/L and a detection limit of 2.1 × 10^–10 mol/L are obtained. Changing the number of thymine to 10 and 6, it leads to a narrow detection range but a high sensitivity. Besides, DNA‐based CL nanoprobes exhibit a remarkable selectivity for Hg²⁺ ions over a variety of competing metal ions. Copyright © 2012 John Wiley & Sons, Ltd.     

Immobilization of bovine serum albumin as a sensitive biosensor for the detection of trace lead ion in solution by piezoelectric quartz crystal impedance

A biosensor based on bovine serum albumin (BSA) for the detection of lead (Pb(2+)) ion was developed and characterized. BSA was immobilized onto a colloidal Au-modified piezoelectric quartz crystal (PQC) as a biosensor for the detection of Pb(2+) ion by piezoelectric quartz crystal impedance (PQCI). Calibration curves for the quantification of Pb(2+) ion showed excellent linearity throughout the concentration range from 1.0 x 10(-7) to 3.0 x 10(-9)mol/L. The interaction between the Pb(2+) ions and the sensor chip is influenced significantly by the pH of the reaction buffer, and the optimal pH for the experiment was 5.4. Under the optimal conditions, the detection limit of 1.0 x 10(-9)mol/L for Pb(2+) was obtained. Kinetic parameters of the Pb(2+)-BSA interactions were also determined by using this chip. The sensor chip could be regenerated for use by dipping in the ethylenediaminetetraacetic acid (EDTA) solution for approximately 2h, and the chip was used to detect Pb(2+) ion for eight times without obvious signal attenuation.     

Spectrofluorimetric determination of dopamine using 1,5-bis(4,6-dicholro-1,3,5-triazinylamino) naphthalene.

A new fluorescent reagent, 1,5-bis(4,6-dichloro-1,3,5-triazinylamino)naphthalene, containing two active chlorines, was synthesized by a one-step reaction. Under the optimum conditions for the determination of dopamine, the enhanced fluorescence intensity is proportional to the dopamine concentration. The fluorescence intensity was measured at lambda(ex/em) = 400/460 nm, with and without dopamine. The linear range and detection limit for the determination of dopamine were 1.0 x 10(-7) mol/L-5.0 x 10(-5) mol/L and 4.0 x 10(-8) mol/L. This method is simple, practical, can afford good precision and accuracy and can be successfully applied to assess dopamine in injections and human serum samples.     

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.     

Determination of daunomycin at a novel COOH/indium tin oxide ion implantation-modified electrode

A novel COOH+ ion implantation-modified indium tin oxide (COOH/ITO) electrode was prepared for the first time and applied for determination of daunomycin (or daunorubicin [DNR]). The electrode showed higher catalytic activity than bare ITO electrode with good reproducibility and stability. The determination condition of linear voltammetry was optimized. A calibration curve was obtained over the range 2.0 x 10(-7) to 5.0 x 10(-6)mol/L, with a correlation coefficient of 0.9909 and a limit of detection of 1.0 x 10(-7)mol/L. The selectivity of the electrode was illustrated by determination of DNR in samples prepared of urine. X-ray photoelectron spectroscopy (XPS) analysis results showed that the implanted COOH+ maintained characteristics of organic group -COOH. A field emission-scanning electron microscope (FSEM) result showed that the implanted surface caused defects and partial dislocations and formed many active centers.     

Cytogenetical Toxical Effects of Heavy Metals on Vicia faba and Inquires into the Vicia Micro nucleus

Under the treatment of heavy metal ions Pb2+, Cd2+ and Hg2+, the interval of mitotic stage was shortened, and the time of interphase prolonged so that the cell cycle was prolonged in the root-tip cells of broadbean (Vicia faba L. ). With the increase of concentrations of Pb2+, Cd2+ and Zn2+ below 1.0, 0.01 and 10 ppm respectively, the mitosis index (IM) rose in root-tip cells, but IM decreased when the root-tips were treated with the some heavy metal ions above the above-mentioned respective concentrations. IM was inhibited in Hg2+ of any concentrations. Within the concentration of Pb2+, Cd2+, Hg2+ and Zn2+ below 1.0, 0. 50, 5.0, 100.0 ppm respectively, the frequency of micronucleus (MCNF) rose as the concentrations were increased, and lowered as the respective concentrations exceeded those stated above. Similar changes occurred in the frequency of chromosomal aberrations (CAF) when the concentration of Pb2+, Cd2+, Hg2+, Zn2+ were below or above 5.0, 5.0, 0.50, 100.0 ppm respectively. Mn2+ had no significant effects to them. By data processing with the method of gray system control and computer aided drawing to IM, MCNF and CAF, it was shown that the three parameters varied tremendously in different dose-effect ranges. All of which suggested that in order to obtain a reliable results in the environmental monitoring and hazardous material detection, genetoxicity inspection should be carried out under the optimal condition when (1) the concentration of the heavy metal to be detected does not seriously inhibit mitosis and (2) CAF and MCNF is in positive correlation.     

Determination of bisphenol A using a flow injection inhibitory chemiluminescence method.

A new flow injection chemiluminescence (CL) method has been developed for the determination of bisphenol A (BPA), based on the inhibitory effect of BPA on the chemiluminescence reaction between luminol and potassium hexacyanoferrate. Under optimum conditions, the decrease in CL emission intensity was linear with BPA concentration in the range 8.0 x 10(-7)-1.2 x 10(-5) mol/L, and the detection limit was 3.1 x 10(-7) mol/L. The relative standard deviation (RSD) of 11 replicate measurements was 2.6% for 2.0 x 10(-6) mol/L BPA (n = 11). The sampling frequency was calculated to be ca. 120/h. This method has been successfully used to determine the content of BPA in aqueous solution of polycarbonate materials. A brief discussion on the possible chemiluminescence reaction mechanism is presented.     

Determination of cardamonin using a chemiluminescent flow-injection method

A sensitive and selective flow injection chemiluminescence method for the determination of cardamonin over the range 1.0 x 10(-8) to 8.0 x 10(-6) g/mL is described. The method is based on the enhancement by cardamonin of the chemiluminescence of the reaction between cerium (IV) and rhodamine 6G in sulphuric acid medium. The optimised flow injection procedure yielded a detection limit for cardamonin of 8.8 x 10(-9) g/mL, whilst the relative standard deviations of intraday and inter-day precision were below 2.5%. The method has the advantages of high sensitivity and a wide linear range. It was successfully applied to the determination of cardamonin in Alpinia katsumadai Hayata. The mechanism of the chemiluminescence reaction is proposed.