Catalytic behavior of tris(2,2'-bipyridine)iron(II) complex in chemiluminescence reaction of luminol in reversed micellar medium of cetyltrimethylammonium chloride

Tris(2,2'-bipyridine) complex of iron(II) was found to cause an increase in the chemiluminescence (CL) emission of luminol dispersed in the reversed micellar medium of cetyltrimethylammonium chloride (CTAC) in 1:1 (v/v) dichloromethane-cyclohexane/water, when the iron(II) complex in dichloromethane was mixed directly with the reversed micellar solution containing luminol. Visible absorption measurements showed that, when dispersed in the CTAC reversed micellar medium, the iron(II) complex dissociates easily. In the reverse micelle, subsequently the free iron(II) ion produced may catalyze the CL oxidation of luminol even in the absence of hydrogen peroxide. The CL emission produced under the optimized experimental conditions was detectable at a minimum iron(II) concentration of 1.0 x 10(-9) M using a flow injection system.     

Peroxidase-catalysed luminol chemiluminescence method for the determination of glutathione

A luminol chemiluminescence (CL) method was developed for the determination of glutathione (GSH). GSH was indirectly determined by measuring the amount of hydrogen peroxide formed during the Cu(II)-catalysed oxidation of GSH with oxygen. The amount of hydrogen peroxide formed was continuously measured using the Arthromyces ramosus peroxidase-catalysed luminol CL reaction. The CL intensities at maximum light emission were linearly correlated with the concentration of GSH over the range 7.5 x 10(-7)-3.0 x 10(-5) M. The detection limit for GSH was about 10 times better than that of the spectrophotometric method using Ellman reagent.     

Flow-injection electrogenerated chemiluminescence determination of isoniazid using luminol.

Based on a new electrogenerated chemiluminescence (ECL) analytical idea, this paper explains a sensitive and selective flow-injection ECL method using luminol for the determination of isoniazid, based on the sensitizing effect of isoniazid for the weak ECL emission of electrochemically oxidized luminol. Under the optimum experimental conditions, the relative ECL intensity was linear with isoniazid concentration in the range of 4.0 x 10(-8) mol/L to 8.0 x 10(-6) mol/L and with a detecting limit of 2.8 x 10(-8) mol/L.     

流动注射化学发光法测定盐酸羟苄唑

基于在碱性条件下盐酸羟苄唑能够与鲁米诺产生化学发光的现象,建立了流动注射化学发光测定盐酸羟苄唑的新方法。盐酸羟苄唑的浓度在8×10-7~1×10-4mol/L范围内与化学发光强度呈良好的线性关系,方法的(3σ)检出限为3×10-7mol/L,对1×10-5mol/L的盐酸羟苄唑连续11次测定的相对标准偏差为1.7%,回收率为96%~103%。已用于滴眼液中盐酸羟苄唑的测定。     

Development of a luminol-based chemiluminescence flow-injection method for the determination of dichlorvos pesticide

A simple, fast chemiluminescence (CL) flow-injection method based on the reaction of luminol with H₂O₂ in the presence of a cationic surfactant (cyltrimethylammonium bromide, CTMAB) has been described for the direct determination of dichlorvos pesticide (DDVP). Under the optimal conditions, the CL intensity was linear to the DDVP concentration in the range of 0.02–3.1 μg ml⁻¹ (r=0.9998, n=10). The relative standard deviation was 3.4% at 0.35 μg ml⁻¹ (n=10), with a detection limit (3σ) of 0.008 μg ml⁻¹ DDVP. The possible reaction mechanism was also discussed. This method has been successfully applied to the determination of trace DDVP residue in vegetable sample and results have been compared with that of the UV method.     

流动注射-化学发光法测定十六烷基三甲基溴化铵的临界胶束浓度

采用流动注射技术，研究了CTAB-Luminol-H2O2体系的化学发光行为。CTAB对Luminol-H2O2体系的化学发光强度有明显的增强作用，并且在临界胶束浓度出现最大值，从而建立了流动注射-化学发光法直接测定CTAB的CMC的一种新方法，并给出了可能的作用机理。     

Flow-through chemiluminescence sensor using immobilized oxidases for the selective determination of L-glutamate in a flow-injection system.

A selective and sensitive chemiluminometric flow sensor for the determination of L-glutamate in serum, based on immobilized oxidases such as glutamate oxidase (GOD), uricase (UC) and peroxidase (POD), is described herein. The principle for the selective chemiluminometric detection for L-glutamate is based on coupled reactions of four sequentially aligned immobilized oxidases, UC/POD/GOD/POD in a flow cell. The immobilized UC was employed to decompose urate, which is one of the major interfering components in serum for a luminol-H2O2 chemiluminescence reaction. The H2O2 produced from the UC reaction readily reacted with reducing components, such as ascorbate and glutathione, and then the excess H2O2 was decomposed by the immobilized POD. L-Glutamate in the sample plug was enzymatically converted to H2O2 with immobilized GOD. Subsequently, the peroxide reacts with luminol on the immobilized POD to produce chemiluminescence, proportional to glutamate concentration. The enzymes were immobilized on tresylated poly(vinyl alcohol beads). The immobilized enzymes were packed into TPFE tube (1.0 mm i.d. x 60 cm), in turn, and used as a flow cell. The sampling rate was 30 h-1. The calibration graph for L-glutamate is linear for 20 nM-5 microM; the detection limit (signal-to-noise = 3) is 10 nM.     

Direct determination of horseradish peroxidase encapsulated in liposomes by using luminol chemiluminescence.

Horseradish peroxidase (HRP) encapsulated in liposomes was directly detected by using luminol chemiluminescence (CL) with H2O2 without lysis of liposomes. At a low concentration of H2O2, the initial rate of HRP-catalyzed luminol CL in liposomes was slower than that of HRP-catalyzed luminol CL in a lipid-free bulk solution. The decrease in the initial rate of the CL reaction in liposomes was due to the membrane permeation of luminol and H2O2. At a high concentration of H2O2, the initial rate of the CL reaction in liposomes was the same as that in a lipid-free bulk solution. The CL measurement conditions in both a lipid-free bulk solution and in liposomes were optimized in the concentrations of luminol and H2O2 by measuring the CL response curves, in which only one peak appeared and the CL intensity was maximal. The CL intensity observed in HRP-catalyzed luminol CL in liposomes was a factor of seven greater than that observed in a lipid-free bulk solution. The CL intensity was dependent on the amount of HRP-encapsulated liposomes used. The detection limit in the direct detection of HRP encapsulated in liposomes was sensitive by a factor of 3 compared with that in HRP-catalyzed luminol CL in a lipid-free bulk solution.     

A flow injection chemiluminescence method for the determination of fluoroquinolone derivative using the reaction of luminol and hydrogen peroxide catalyzed by gold nanoparticles

Based on the enhancement of chemiluminescence (CL) of luminol-hydrogen peroxide-gold nanoparticles system by fluoroquinolones (FQs), a novel and rapid CL method is reported for the determination of FQs derivatives. Under the optimum conditions, the CL intensity is proportional to the concentration of FQs derivative in solution. The corresponding linear regression equations are established over the range of 0.08-1.28 μg/mL for norfloxacin, 0.013-1.32 μg/mL for ciprofloxacin, 0.014-1.4 μg/mL for lomefloxacin, 0.029-1.46 μg/mL for fleroxacin, 0.02-1.0 μg/mL for ofloxacin and 0.01-1.44 μg/mL for levofloxacin, respectively. The limits of detection (S/N = 3) are 3.2, 9.5, 7.0, 9.0, 8.0, and 8.0 ng/mL with the relative standard deviation (n = 11) 4.3, 1.5, 1.9, 1.3, 1.6 and 2.1% for norfloxacin, ciprofloxacin, lomefloxacin, fleroxacin, ofloxacin and levofloxacin, respectively. This proposed method has been applied to detect FQs derivatives in human urine successfully.     

A new luminol chemiluminescence reaction using a tetravalent nickel-periodate complex as the oxidant

A modified sequential extraction procedure was developed and applied to characterize the species of metals in fly ash. Two fly ash samples were collected from a coal-fired thermal power plant located in the north of China. A sample was collected from the conventional pulverized coal (PC) combustor and another from the circulating fluidized bed (CFB) combustor. After extraction by the proposed sequential extraction procedure, the elements in the fly ash samples were divided into a water-extractable fraction (F1), an acid-soluble fraction (F2), a reducible fraction (F3), an oxidizable fraction (F4) and a residual fraction (F5). Except for Cu, V, Cd in the PC sample and V, Zn in the CFB sample, most of the other metals were present in the residual fraction (F5), which was very difficult to release into the environment. The fraction distribution patterns in the two samples were also compared. The results indicated that the distribution of metals in different fractions in fly ash samples were probably impacted by different combustion processes.     

A flow-injection chemiluminescence method for the determination of some estrogens by enhancement of luminol-hydrogen peroxide-tetrasulfonated manganese phthalocyanine reaction

A novel flow-injection chemiluminescence (FI-CL) method for the determination of estrogens is proposed, based upon its enhancing effect on the CL reaction of luminol with hydrogen peroxide catalyzed by tetrasulfonated manganese phthalocyanine (MnTSPc) in alkaline solution. Under the selected experimental conditions, a linear relationship was obtained between the CL intensity and the concentration of estrone in the range of 1.0 × 10⁻⁷ to 1.0 × 10⁻⁶ mol/l, estradiol in the range of 9.0 × 10⁻⁸ to 1.0 × 10⁻⁶ mol/l and estriol in the range of 3.0 × 10⁻⁷ to 2.0 × 10⁻⁶ mol/l, respectively. The detection limits were 5.1 × 10⁻⁸ mol/l for estrone, 7.2 × 10⁻⁹ mol/l for estradiol and 6.5 × 10⁻⁸ mol/l for estriol with a relative standard deviation of 2.8% for 5.0 × 10⁻⁷ mol/l estrone, 2.4% for 1.0 × 10⁻⁷ mol/l estradiol, and 3.1% for 7.0 × 10⁻⁷ mol/l estriol (n = 11). This method has been applied to the determination of estrogen in pharmaceutical injections and tap water with satisfactory results.     

Enzymatic assay with detection by enhanced luminol chemiluminescence in a reversed micellar system: determination of l-amino acids and glucose

A detection system for hydrogen peroxide, i.e., luminol chemiluminescence (CL) in a hexadecyltrimethylammonium bromide (CTAB) reversed micellar system, was coupled to enzyme reactions. The use of CTAB reversed micellar medium allows one to conduct both the oxidase enzymatic and CL detection reactions simultaneously at mild pH (l-amino acid system, pH 8.7; glucose system, pH 8.5) in the absence of any co-oxidant or catalyst. Based on this result, simple and unique determinations of l-amino acids and glucose as substrates were developed. The calibration graph for a representative amino acid, l-phenylalanine, was linear in the concentration range 4.0×10^?6?200×10^?6M with a relative standard deviation of 5.78% (five determinations). The method established for l-phenylalanine was also applicable for the assay of fourteen other l-amino acids. The calibration graph for glucose was linear in the concentration range 5.4×10^??540×10^?6M with a relative standard deviation of 4.27% (eight determinations). This method was compared with a standard spectrophotometric method (hexokinase) and successfully applied to the determination of glucose in human serum.     

鲁米诺-铁氰化钾化学发光体系测定双嘧达莫

在碱性条件下,铁氰化钾氧化鲁米诺产生化学发光,双嘧达莫对该体系的化学发光有显著的增强作用。基于此并结合流动注射技术建立了测定双嘧达莫的新方法。该方法检出限为5.7×10-11g mL(IUPAC),线性范围为1.0×10-10～5.0×10-8g mL,对5.0×10-9g mL双嘧达莫平行测定11次,其相对标准偏差为1.9%。     

A lanthanide sensitized chemiluminescence method of flow-injection for the determination of ulifloxacin and prulifloxacin

A lanthanide sensitized chemiluminescence method of flow-injection was developed for the determination of a new fluoroquinolone, ulifloxacin (UFX), and its prodrug prulifloxacin (PUFX). The proposed method was based on the remarkable chemiluminescence enhancement effect of UFX (PUFX) on KMnO₄−Na₂S₂O₄−Ln(III). Tb(III) ion was chosen from lanthanides because it showed the best sensitizing effect. Under optimized experimental conditions, the relative chemiluminescence intensity was in linear relationship with UFX and PUFX concentrations in the ranges of 1.0 × 10⁻⁸ − 5.0 × 10⁻⁶ M and 9.0 × 10⁻⁹ − 5.0 × 10⁻⁶ M, respectively. The minimum detectable value and relative standard deviation were 5.5 × 10⁻⁹ M, 1.5% for UFX and 7.0 × 10⁻⁹ M, 2.9% for PUFX, respectively. The proposed method was applied to the determination of UFX in spiked human serum and urine, and of PUFX in tablets with satisfactory results. The possible mechanism of chemiluminescence was also proposed. The text was submitted by the authors in English.     

A simple flow-injection chemiluminescence method for the determination of trace pentavalent vanadium in water samples

A simple method for rapid determination of trace pentavalent vanadium in natural water was presented by flow-injection chemiluminescence (CL). Through water injection, luminol and potassium permanganate were eluted from the anion exchange column to generate the CL, which was enhanced in the presence of V(V). Under the optimum conditions, the increased CL intensity was linear with V(V) concentration in the range from 0.1 to 100?ng?mL^?1. The limit of detection was 50?pg?mL^?1 (3σ) and the relative standard deviation (RSD) was 2.24% (n?=?5) for a 1.0?ng?mL^?1?V(V). At a flow rate of 2.0?mL?min^?1, one cycle of analysis could be performed in 0.5?min with a RSD of less than 3.0%. The proposed method was successfully applied to the determination of vanadium in natural water.     

Flow-injection spectrophotometric determination of novalgin in pharmaceuticals using micellar medium.

A sensitive flow-injection (FI) procedure with spectrophotometric detection in a micellar medium is proposed for the determination of novalgin. The method is based on the instantaneous formation of a red-orange product (lambda(max) = 510 nm) after the reaction between novalgin and p-dimethylaminocinnamaldehyde (p-DAC) in a dilute acid medium. The sensitivity of this reaction was increased by a factor of 5.6 in the presence of sodium dodecyl sulfate (SDS). Experimental design methodologies were used to optimize the chemical and FI variables. The calibration curve was linear in the range of 1.45 x 10(-6) to 2.90 x 10(-5) mol L(-1) with an excellent correlation coefficient (r = 0.9999). The detection limit was 1.31 x 10(-7) mol L(-1) (n = 20, RSD = 2.0%). No interferences were observed from the common excipients. The results obtained by the proposed method were favorably compared with those given by the iodometric reference method at 95% confidence level.     

Improved detection of salicylic acids using terbium-sensitized luminescence in aqueous micellar solutions of cetyltrimethylammonium chloride

The determination of salicylic, p-aminosalicylic and 5-fluorosalicylic acids was investigated using terbium-sensitized luminescence in aqueous solutions. Formation of a ternary chelate between terbium, EDTA and the salicylic acid requires dissociation of the phenol group which is adjacent to the dissociated carboxylic group. The reaction is obtained in alkaline solutions and is enhanced in the presence of cetyltrimethylammonium chloride. As evidenced by absorbance and fluorescence measurements, the cationic surfactant plays an important role in the formation of the ternary chelate and then terbium luminescence depends mainly on the extent of chelate formation. Linearity is found over more than four orders of magnitude and detection limits are in the range (2-4) x 10(-10) mol l-1 for the three acids.     

An ultrasensitive and highly selective determination method for quinones by high-performance liquid chromatography with photochemically initiated luminol chemiluminescence

Quinones are a class of compounds of substantial toxicological and pharmacological interest. An ultrasensitive and highly selective chemiluminescence (CL) method was newly developed for the determination of quinones based on the utility of photochemically initiated luminol CL. The method involved ultraviolet (UV) irradiation of quinones to generate reactive oxygen species (ROS) through the unique photosensitization reaction accompanied with the photolytical generation of 3,6-dihydroxyphthalic acid (DHPA) from quinones. The photoproducts were detected by luminol CL reaction. Interestingly, it was noticed that DHPA had enhancement effect for the luminol CL. The generation of the enhancer (DHPA) in association with the oxidant (ROS) in the photochemical reaction greatly increases the sensitivity and selectivity of the proposed luminol CL method. In order to elucidate the type of ROS produced by the photosensitizaion reaction in relation to the proposed CL reaction, we investigated the quenching effect of selective ROS scavengers in the luminol CL. Although several ROS were generated, superoxide anion was the most effective ROS for the generated CL. Moreover, the enhancement mechanism of DHPA for luminol CL was confirmed. The enhancement was found to be through the formation of stabilized semiquinone anion radical that provided long-lived CL. The generation of the semiquinone radical was confirmed by electron spin resonance technique. Furthermore, we developed an HPLC method with on-line photochemical reaction followed by the proposed CL detection for the determination of four quinones. A luminol analogue, L-012, was used for its high sensitivity. The detection limits for quinones obtained with the proposed method (S/N = 3) were in the range 1.5–24 fmol that were 10–1000 times more sensitive compared with the previous methods. Finally, the developed HPLC-CL system was successfully applied for the determination of quinones in airborne particulate samples collected at Nagasaki city.     

Use of amino-carbonyl reaction and chemiluminescence detection to the flow-injection determination of some amino acids

Some amino acids were found to react with carbonyl functional groups of humic acid. Products of this reaction give strong chemiluminescence during their oxidation with N-bromosuccinimide (NBS) in alkaline solution. Humic acids from different sources produced similiar signal magnitude. This effect was employed to the flow-injection determination of glycine and arginine in pharmaceutical formulations with considerable selectivity against different amino compounds. The proposed method is fast and simple. Detection limit is 0.20 and 0.25 mg.l(-1) for glycine and arginine respectively, and 115 samples per h can be determined.     

Spectrofluorimetric determination of thiabendazole in a micellar medium

A sensitive, selective Spectrofluorimetric method has been developed for the determination of thiabendazole in a sodium dodecylsulphate micellar medium. The method features a linear determination range of 0.020-15 g and a detection limit of 0.2 ng/ml, with a relative standard deviation of less than 3%. By using a straightforward extraction procedure with ethyl acetate and hydrochloric acid, the method provided average thiabendazole recoveries above 96% from apple, pear and potato samples.