Determination of carbamazepine by chemiluminescence detection using chemically prepared tris(2,2'-bipyridine)ruthenium(III) as oxidant.

A new chemiluminescence method for the determination of carbamazepine (CBZ) has been developed. The method is based on the chemiluminescence produced in the reaction of tris(2,2'-bipyridine)ruthenium(III) and CBZ in an acidic medium. The chemiluminescence intensity was enhanced by organic solvents in the reaction system. Under the optimum experimental conditions, the calibration curve was linear over the range 4.0 x 10(-3)-8.6 x 10(-7) mol/L for CBZ. The detection limit (S/N = 3) was 2.5 x 10(-7) mol/L and the relative standard deviation of six replicate measurements was 2.6% for 4.0 x 10(-4) mol/L of CBZ. The possible reaction mechanism were also discussed. The chemiluminescence method was successfully applied to assay the CBZ contents in pharmaceutical tablets.     

Highly sensitive and simple method for measurement of pipecolic acid using reverse-phase ion-pair high performance liquid chromatography with tris(2,2'-bipyridine)ruthenium(III) chemiluminescence detection

A new, highly sensitive chemiluminescence method for measurement of pipecolic acid in various substances such as human serum, cow's milk, beer, and apple juice has been developed. The method is based on reverse-phase ion-pair high performance liquid chromatographic separation and subsequent tris(2,2'-bipyridine)ruthenium(III) chemiluminescence detection. It was confirmed that imino acids show strong chemiluminescence upon mixing with tris(2,2'-bipyridine)ruthenium(III). A calibration graph, based on a standard pipecolic acid solution, was linear over the range 5.0x10(-9)M to 2.0x10(-5)M and the detection limit was 24fmol (signal-to-noise ratio=3). This highly sensitive and selective determination method can be applied to selected samples without purification or pre-concentration procedures. Compared to the previous HPLC methods, the proposed method is easier, more sensitive, and time-saving.     

Flow-injection chemiluminometric determination of some thioxanthene derivatives in pharmaceutical formulations and biological fluids using the [Ru(dipy)3(2+)]-Ce(IV) system.

A flow-injection (FI) methodology using tris(2,2'-dipyridyl)ruthenium(II), [Ru(dipy)3(2+)], chemiluminescence (CL) was developed for the rapid and sensitive determination of three thioxanthene derivatives, namely zuclopenthixol hydrochloride, flupentixol hydrochloride and thiothixene. The method is based on the CL reaction of the studied thioxanthenes with [Ru(dipy)3(2+)] and Ce(IV) in a sulfuric acid medium. Under the optimum conditions, calibration graphs were obtained over the concentration ranges 0.002-6 migrograms/ml for zuclopenthixol hydrochloride, 0.5-15 micrograms/ml for flupentixol hydrochloride and 0.05-7.5 micrograms/ml for thiothixene. The limits of detection (s/n = 3) were 4.2 x 10(-9) mol/l zuclopenthixol hydrochloride, 2 x 10(-8) mol/l flupentixol hydrochloride and 4.5 x 10(-8) mol/l thiothixene. The method was successfully applied to the determination of these compounds in dosage forms and biological fluids.     

Chemiluminescence of tryptophan and histidine in Ru(bpy)3(2+)-KMnO4 aqueous solution

Amino acids with different chemical structures have different abilities in terms of increasing the intensity of chemiluminescence (CL) of tris(2,2'-bipyridine)ruthenium(II) [Ru(bpy)3(2+)]. In a flow system, CL caused by the reaction between Ru(bpy)3(3+) and 15 amino acids was observed, but only tryptophan (Trp) and histidine (His) enhanced the intensity obviously, and so the CL of Trp and His and their molecular groups was studied. A calculation of the ionization potentials (IPs) of their N atom indicated that the CL intensities of these compounds depended on their IPs. In addition, the flow system was used for the determination of Trp and His, and the detection limits were 3 x 10(-8) mol L(-1) for His and 2.5 x 10(-9) mol L(-1) for Trp. The calibration curves for the two amino acids were 1.0 x 10(-7) to 5.0 x 10(-3) mol L(-1) for His and 1.0 x 10(-8) to 1.0 x 10(-4) mol L(-1) for Trp. The proposed approach was applied to the determination of His in Ganoderma.     

Chemiluminescence of cobalt(II)-hydrogen peroxide-hydrogencarbonate in the absence of luminescent reagents

A novel chemiluminescence (CL) system, cobalt(II)-hydrogen peroxide-hydrogencarbonate without luminescent reagents, was described. When cobalt(II) was injected into mixed solution of 0.4 mol l(-1) hydrogencarbonate and 0.01 mol l(-1) hydrogen peroxide in a flow injection system, CL occurred, which was significantly enhanced when rhodamine B coexisted. The CL emission intensity was found correlation with the concentration of cobalt(II) in the range of 2.0x10(-9)-1.0x10(-5) mol l(-1) with a detection limit of 1.2x10(-9) mol l(-1) cobalt(II). The relative standard derivative (RSD) for 5.0x10(-7) mol l(-1) cobalt(II) was 1.6% based on nine repetitive measurements. In addition to cobalt(II), other metal ions were also investigated, and only chromium(III) gave out measurable CL emission. The possible mechanism was discussed based on the CL emission spectrum.     

A fluorescent chemosensor for copper(II) based on a carboxylic acid-functionalized tris(2,2'-bipyridine)-ruthenium(II) complex.

In this research, bis(2,2'-bipyridine)(4-methyl-2,2'-bipyridine-4'-carboxylic acid)ruthenium(II).2PF(6)- complex (1), was first used as a fluorescent chemosensor to recognize Cu(II) in EtOH/H(2)O (1:1, v/v) solution. The response of the sensor is based on the fluorescence quenching of complex 1 by binding with Cu(II). The analytical performance characteristics of the proposed Cu(II)-sensitive chemosensor were investigated. The sensor can be applied to the quantification of Cu(II) with a linear range covering from 5.0 x 10(-8) to 1.0 x 10(-4) M and a detection limit of 4.2 x 10(-8) M. The experiment results show that the response behavior of 1 to Cu(II) is pH independent in medium condition (pH 4.0 - 8.0), and show excellent selectivity for Cu(II) over other transition metal cations.     

Chemiluminescence investigation of NH(2)OH-fluorescein-Cu(2+) system and its application to copper analysis in serum

A novel chemiluminescent system, fluorescein-NH(2)OHOH(-), was developed for the determination of copper(II) in serum. A weak light emission arises from hydroxylamine in the presence of the organic reagent fluorescein in basic aqueous solution. Under the conditions of 1.2 x 10(-3) mol l(-1) NH(2)OH and 5 x 10(-3) mol l(-3) fluorescein, the light intensity is linearly dependent upon the concentration of copper(II) within the range 1-20 ppb. The relative standard deviation of the determination of copper(II) is 4.2% (n = 13) and the detection limit is 0.5 ppb. The system is highly selective for copper except in the presence of iron(II,III) and cobalt(II). In conjunction with potassium fluoride as masking agent, the method was successfully applied to the determination of microamounts of copper(II) in serum. A mechanistic study of the chemiluminescence reaction is also discussed.     

The enhanced electrogenerated chemiluminescence of Ru(bpy)3(2+) by glutathione on a glassy carbon electrode modified with some porphine compounds

It has been found that the electrochemical activity of glutathione was increased greatly at the glassy carbon electrodes modified with 5,10,15,20-tetraphenylporphine ruthenium(II) carbenyl (RuTPP), meso-tetraphenylporphine copper(II) complex (CuTTP) and hemin. It has been also found that glutathione would enhance the electrogenerated chemiluminescence (ECL) of Ru(bpy)3(2+) at a hemin glassy carbon electrode; the enhanced ECL intensity was linear with the concentration of glutathione in the range of 1 x 10(-7)-1 x 10(-4) mol l-1, based on which method for determination of glutathione has been developed. The detection limit of glutathione was 2 x 10(-8) mol l-1, and the relative standard deviation for 1 x 10(-6) mol l-1 glutathione was 2.7%. The mechanism for this ECL system has been proposed.     

Chemiluminescence muTAS for the determination of atropine and pethidine

A novel chemiluminescence micro-total analytical system (muTAS) is described for the determination of atropine and pethidine. Reagents were moved though the 200-mum wide channels of a glass chip using a negative pressure pumping system. Linear calibrations were obtained for the system over three-orders of magnitude, with detection limits of 3.8x10(-9) and 7.7x10(-8) M, respectively for atropine and pethidine and R.S.D. of <5%. This is the first report on the use of muTAS to determine atropine with chemically oxidised tris (2,2'-bipyridine)ruthenium(II) chemiluminescence.     

Effect of oxidant type on the chemiluminescence intensity from the reaction of tris(2,2′-bipyridyl)ruthenium(III) with various organic acids

An investigation into the chemiluminescence of fourteen organic acids and tris(2,2′-bipyridyl)ruthenium(II) was undertaken. Particular emphasis was placed upon the method of production of the reagent, tris(2,2′-bipyridyl)ruthenium(III), with cerium(IV) sulfate, potassium permanganate, lead dioxide and electrochemical generation. Analytically useful chemiluminescence was observed when Ce(IV) or potassium permanganate were employed as oxidants. The kinetics of analyte oxidation was related to the intensity of the chemiluminescence emission, which increased by three orders of magnitude for tartaric acid after 40 h of oxidation.     

Sensitive determination of metal ions by liquid chromatography with tris(2,2'-bipyridine) ruthenium (II) complex electrogenerated chemiluminescence detection.

Emetine dithiocarbamate metal complex, which is prepared from emetine, carbon disulfide, and metal (II), was found to indicate a large chemiluminescence intensity on the electrogenerated chemiluminescence of tris(2,2'-bipyridine)ruthenium(II). Liquid chromatography equipped with the chemiluminescence detection was developed for analyzing trace metal ions by use of the metal complex formation. The mixture of the Cu(II) and Co(II) complexes as a model sample was injected into the LC system. The two metal complexes and an excess emetine were successfully separated. The Cu(II) and Co(II) complexes were determined over the range 1-300 nM (the detection limit of 650 fg) and 30-5000 nM (the detection limit of 17 pg), respectively.     

Detection of clindamycin by capillary electrophoresis with an end-column electrochemiluminescence of tris(2,2'-bypyridine)ruthenium(II)

Coupled capillary electrophoresis (CE) with end-column electrogenerated chemiluminescence (ECL) was adopted for the quantitative detection of clindamycin. Clindamycin enhanced ECL intensity of tris(2,2'-bypyridine)ruthenium(II) (Ru(bpy)(3)(2+)) as a coreactant. Under the optimized conditions, the ECL intensity was linear with the concentration of clindamycin over the range from 5.0 x 10(-7) to 1.0 x 10(-4)M with a detection limit of 1.4 x 10(-7)M. The proposed CE-ECL was successfully applied for the detection of clindamycin in pharmaceutical and clinic samples. The interaction of clindamycin with hemoglobin was also investigated. The binding constant of clindamycin with hemoglobin was estimated to be 3.6 x 10(3)M(-1).     

Chemiluminescence determination of sulfite in sugar and sulfur dioxide in air using Tris(2,2'-bipyridyl)ruthenium(II)-permanganate system

A chemiluminescence (CL) detection for the determination of sulfite using the reaction of Ru(bipy)(3)(2+) (bipy=2,2'-bipyridyl) -SO(3)(2-)-KMnO(4) is described. The concentration of sulfite is proportional to the CL intensity from 5.0x10(-8) to 1.25x10(-4) mol l(-1). The limit of detection is 2.5x10(-8) mol l(-1) and the relative standard deviation is 4.9% for the 2x10(-5) mol l(-1) sulfite solution in six repeated measurements. This method has been successfully applied to the determination of sulfite in sugar and sulfur dioxide in air by using triethanolamine (TEA) as the absorbent material.     

Luminescent ruthenium(II) polypyridine biotin complexes: synthesis, characterization, photophysical and electrochemical properties, and avidin-binding studies

Two luminescent ruthenium(II) polypyridine complexes containing a biotin moiety [Ru(bpy)(2)(L1)](PF(6))(2) (1) and [Ru(bpy)(2)(L2)](PF(6))(2) (2) (bpy = 2,2'-bipyridine; L1 = 4-(N-((2-biotinamido)ethyl)amido)-4'-methyl-2,2'-bipyridine; L2 = 4-(N-((6-biotinamido)hexyl)amido)-4'-methyl-2,2'-bipyridine) have been synthesized and characterized, and their photophysical and electrochemical properties have been studied. Upon photoexcitation, complexes 1 and 2 display intense and long-lived triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ru) --> pi*(L1 or L2)) emission in fluid solutions at 298 K and in low-temperature glass. We have studied the binding of these ruthenium(II) biotin complexes to avidin by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays, luminescence titrations, competitive assays using native biotin, and quenching experiments using methyl viologen. On the basis of the results of these experiments, a homogeneous competitive assay for biotin has been investigated.     

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.     

Time-resolved photoacoustics study of the ruthenium(II) bis(2,2'-bipyridine)(4,4'-dicarboxy-2,2'-bipyridine) complex

The formation and the decay of the triplet metal to ligand charge transfer state ((3)MLCT) of ruthenium(II) bis(2,2'-bipyridine)(4,4'-dicarboxy-2,2'-bipyridine) (Ru(bpy)(2)(dcbpy)) were characterized using photoacoustic calorimetry. At pH 6 and 2, the (3)MLCT state formation leads to a volume change of -8 mL mol(-1) and enthalpy changes of 17 kcal mol(-1) and 13 kcal mol(-1), respectively. We attribute the volume contraction to structural changes and to solvent electrostriction. At pH 4, the photoexcitation of the complex leads to an expansion of 14 mL mol(-1) and an enthalpy change of approximately 119 kcal mol(-1) due to protonation of the carboxyl group in the excited state.     

毛细管电泳-电化学发光法测定盐酸曲马多制剂及血浆中曲马多

采用毛细管电泳结合柱末电化学发光检测器提出了测定盐酸曲马多制剂及血浆中曲马多含量的方法。检测的原理系基于曲马多分子中的叔氨基对在pH9的磷酸盐缓冲介质中钌联吡啶络离子[Ru(Bpy)23+]与溶解氧在铂盘工作电极上反应的电化学发光的增强作用。对毛细管电泳及电化学发光检测的试验条件进行了优化。在优化的试验条件下,制剂中曲马多在1.0×10-8～7.0×10-6mol.L-1,血浆中曲马多在2.0×10-7～6.0×10-6mol.L-1范围内呈线性,检出限(3S/N)分别为7.0×10-9mol.L-1和1.0×10-7mol.L-1。采用该方法对盐酸曲马多制剂和血浆中曲马多的浓度分别进行了测定,所得平均回收率分别为98.9%和89.9%。     

Synthesis and characterization of tris(heteroleptic) Ru(II) complexes bearing styryl subunits

We have developed and optimized a well-controlled and refined methodology for the synthesis of substituted π-conjugated 4,4'-styryl-2,2'-bipyridine ligands and also adapted the tris(heteroleptic) synthetic approach developed by Mann and co-workers to produce two new representative Ru(II)-based complexes bearing the metal oxide surface-anchoring precursor 4,4'-bis[E-(p-methylcarboxy-styryl)]-2,2'-bipyridine. The two targeted Ru(II) complexes, (4,4'-dimethyl-2,2'-bipyridine)(4,4'-di-tert-butyl-2,2'-bipyridine)(4,4'-bis[E-(p-methylcarboxy-styryl)]-2,2'-bipyridine) ruthenium(II) hexafluorophosphate, [Ru(dmbpy)(dtbbpy)(p-COOMe-styryl-bpy)](PF(6))(2) (1) and (4,4'-dimethyl-2,2'-bipyridine)(4,4'-dinonyl-2,2'-bipyridine)(4,4'-bis[E-(p-methylcarboxy-styryl)]-2,2'-bipyridine) ruthenium(II) hexafluorophosphate, [Ru(dmbpy)(dnbpy)(p-COOMe-styryl-bpy)](PF(6))(2) (2) were obtained as analytically pure compounds in high overall yields (>50% after 5 steps) and were isolated without significant purification effort. In these tris(heteroleptic) molecules, NMR-based structural characterization became nontrivial as the coordinated ligand sets each sense profoundly distinct magnetic environments greatly complicating traditional 1D spectra. However, rational two-dimensional approaches based on both homo- and heteronuclear couplings were readily applied to these structures producing quite definitive analytical characterization and the associated methodology is described in detail. Preliminary photoluminescence and photochemical characterization of 1 and 2 strongly suggests that both molecules are energetically and kinetically suitable to serve as sensitizers in energy-relevant applications.     

Evaluation of luminol-H(2)O(2)-KIO(4) chemiluminescence system and its application to hydrogen peroxide, glucose and ascorbic acid assays

A novel chemiluminescence (CL) system was evaluated for the determination of hydrogen peroxide, glucose and ascorbic acid based on hydrogen peroxide, which has a catalytic-cooxidative effect on the oxidation of luminol by KIO(4). Hydrogen peroxide can be directly determined by luminol-KIO(4)-H(2)O(2) CL system. The detection limit was 3.0x10(-8) mol l(-1) and the calibration graph was linear over the range of 2.0x10(-7)-6.0x10(-4) mol l(-1). The relative standard deviation of H(2)O(2) was 1.1% for 2.0x10(-6) mol l(-1) (N=11). Glucose was indirectly determined through measuring the H(2)O(2) generated by the oxidation of glucose in the presence of glucose oxidase at pH 7.6. The present method provides a source for H(2)O(2), which, in turn, coupled with the luminol-KIO(4)-H(2)O(2) CL reaction system. The CL was linearly correlated with glucose concentration of 0.6-110 mug ml(-1). The relative standard deviation was 2.1% for 10 mug ml(-1) (N=11). Detection limit of glucose was 0.08 mug ml(-1). Ascorbic acid was also indirectly determined by the suppression of luminol-KIO(4)-H(2)O(2) CL system. The calibration curve was linear over the range of 1.0x10(-7)-1.0x10(-5) mol l(-1) of ascorbic acid. The relative standard deviation was 1.0% for 8.0x10(-7) mol l(-1) (N=11). Detection limit of ascorbic acid was 6.0x10(-8) mol l(-1). These proposed methods have been applied to determine glucose, ascorbic acid in tablets and injection.     

Analysis of monosaccharides by capillary electrophoresis with electrochemiluminescence detection.

A capillary electrophoresis with tris(2,2'-bipyridyl)ruthenium(II)-based electrogenerated chemiluminescence detection method was investigated for the determination of monosaccharides using 2-diethylaminoethanethiol as a derivatizing reagent. Xylose, rhamnose, glucose and glucosamine were selected for the demonstration of the method. Under optimal conditions, the calibration curve of glucose was linear over the range of 1.0 x 10(-4) to 1.0 x 10(-7) mol/L (R = 0.999) and the detection limit was 6.0 x 10(-8) mol/L (S/N = 3). The method was successfully applied for the assay of glucose in angelica.