Separation and detection of chlorpromazine hydrochloride and promethazine hydrochloride using electrochemiluminescence followed by capillary electrophoresis

Phenothiazine drugs, chlorpromazine hydrochloride (CPZ) and promethazine hydrochloride (PMZ), were determined with Ru(bpy)(3)(2+) electrochemiluminescene by the capillary electrophoresis (CE-ECL). It was found that both CPZ and PMZ could produce an intermediate that acted as coreactants to react with Ru(bpy)(3)(2+) to produce excited states which were capable of emitting light. This CE-ECL detection method had high sensitivity, good selectivity and reproducibility for CPZ and PMZ determination.

Synthesis and characterization of a novel two-component organogelator based on ion-bonded discotic complex

A novel ion-bonded discotic complex was prepared from 2,3,6,7,10,11-hexakis(N,N-dimethylaminopropylaminocarbonylmethoxy)triphenylene (HDTP) and 4'-dodecyloxybiphenyl-4-carboxylic acid (DBC) by ionic self-assembly (ISA) route and characterized by Fourier transform infrared (FTIR) spectrum. We found that the complex can self-assemble into stable gels in aromatic hydrocarbons. Nanofibers with diameters of 50-130 nm were observed in the gels by transmission electron micrograph (TEM).

A strategy for synthesis of ion-bonded amphiphilic miktoarm star copolymers via supramolecular macro-RAFT agent

Amphiphilic supramolecular miktoarm star copolymers linked by ionic bonds with controlled molecular weight and low polydispersity have been successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using an ion-bonded macromolecular RAFT agent (macro-RAFT agent). Firstly, a new tetrafunctional initiator, dimethyl 4,6-bis(bromomethyl)-isophthalate, was synthesized and used as an initiator for atom transfer radical polymerization (ATRP) of styrene to form polystyrene (PSt) containing two ester groups at the middle of polymer chain. Then, the ester groups were converted into tertiary amino groups and the ion-bonded supramolecular macro-RAFT agent was obtained through the interaction between the tertiary amino group and 2-dodecylsulfanylthiocarbonylsulfanyl-2-methyl propionic acid (DMP). Finally, ion-bonded amphiphilic miktoarm star copolymer, (PSt)(2)-poly(N-isopropyl-acrylamide)(2), was prepared by RAFT polymerization of N-isopropylacrylamide (NIPAM) in the presence of the supramolecular macro-RAFT agent. The polymerization kinetics was investigated and the molecular weight and the architecture of the resulting star polymers were characterized by means of H-1-NMR, FTIR, and GPC techniques. (c) 2008 Wiley Periodicals, Inc.

Electrospun palladium nanoparticle-loaded carbon nanofibers and their electrocatalytic activities towards hydrogen peroxide and NADH

Palladium nanoparticle-loaded carbon nanofibers (Pd/CNFs) were synthesized by the combination of electrospinning and thermal treatment processes. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show that spherical Pd nanoparticles (NPs) are well-dispersed on the surfaces of CNFs or embedded in CNFs. X-ray diffraction (XRD) pattern indicates that cubic phase of Pd was formed during the reduction and carbonization processes, and the presence of Pd NPs promoted the graphitization of CNFs. This nanocomposite material exhibited high electric conductivity and accelerated the electron transfer, as verified by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV).

Simultaneous electrochemical determination of dopamine, uric acid and ascorbic acid using palladium nanoparticle-loaded carbon nanofibers modified electrode

Palladium nanoparticle-loaded carbon nanofibers (Pd/CNFs) were prepared by electrospinning and subsequent thermal treatment processes. Pd/CNFs modified carbon paste electrode (Pd/CNF-CPE) displayed excellent electrochemical catalytic activities towards dopamine (DA), uric acid (UA) and ascorbic acid (AA). The oxidation overpotentials of DA, UA and AA were decreased significantly compared with those obtained at the bare CPE. Differential pulse voltammetry was used for the simultaneous determination of DA, UA and AA in their ternary mixture.

Simultaneous determination of dopamine, ascorbic acid and uric acid with electrospun carbon nanofibers modified electrode

A novel carbon-nanofiber-modified carbon-paste electrode (CNF-CPE) was employed for the simultaneous determination of dopamine (DA), ascorbic acid (AA) and uric acid (UA) with good selectivity and high sensitivity. The CNFs were prepared by combination of electrospinning technique with thermal treatment method and were used without any pretreatment. In application to determination of DA, AA and UA in the ternary mixture, the pristine CNF-CPE exhibited well-separated differential pulse voltammetric peaks with high catalytic current. Low detection limits of 0.04 mu M, 2 mu M and 0.2 mu M for DA, AA and UA were obtained, with the linear calibration curves over the concentration range 0.04-5.6 mu M, 2-64 mu M and 0.8-16.8 mu M, respectively.

Analysis of amphetamines in urine with liquid-liquid extraction by capillary electrophoresis with simultaneous electrochemical and electrochemiluminescence detection

Amphetamines including methamphetamine, 3,4-methylenedioxyamphetamine and 3,4-methylenedioxymethamphetamine were separated and detected by CE using simultaneous electrochemical (EC) and electrochemiluminescence (ECL) detection (CE-EC/ ECL). Factors that influenced the separation and detection performance, such as the detection potential, the pH value and concentration of the running buffer, the separation voltage and the pH of the detection buffer, were investigated.

Synthesis of carbon nanofibers for mediatorless sensitive detection of NADH

Highly sensitive amperometric detection of dihydronicotinamide adenine dinucleotide (NADH) by using novel synthesized carbon nanofibers (CNFs) without addition of any mediator has been proposed. The CNFs were prepared by combination of electrospinning technique with thermal treatment method and were applied without any oxidation pretreatment to construct the electrochemical sensor. In amperometric detection of NADH, a linear range up to 11.45 mu M with a low detection limit of 20 nM was obtained with the CNF-modified carbon paste electrode (CNF-CPE).

Quality analysis of herbal medicine products prepared from Herba sarcandrae by capillary electrophoresis with electrochemical detection

A capillary electrophoresis with electrochemical detection(CE-ED) method was developed for the quality analysis of herbal medicine products prepared from the same herb of Herba Sarcandrae: Fufang Caoshanhu tablets, Qingrexiaoyanning capsules, and Xuekang oral liquids. Under the optimal analysis conditions, the low detection limit[1.0x10(-7) mol/L(S/N=3)] and the wide linear range(1.0x10(-7)-1.0x10(-4) mol/L) were obtained for quality standard compound of isofraxidin. The precisions of the peak current and the migration time(as RSDs) for the real sample analysis were 2.0%-2.6%, and 1.2%-1.8% for isofraxidin, respectively.

Highly efficient electrocatalytic oxidation of formic acid by electrospun carbon nanofiber-supported PtxAu100-x bimetallic electrocatalyst

Electrospun carbon nanofiber-supported bimetallic PtxAu100-x electrocatalysts (PtxAu100-x/CNF) were prepared by electrochemical codeposition method. The composition of PtAu bimetallic nanoparticles could be controlled by varying the ratio of H2PtCl6 and HAuCl4. Scanning electron microscopy images showed that bimetallic nanoparticles had coarse surface morphology with high electrochemically active surface areas. X-ray diffraction analysis testified the formation of PtAu alloys. PtxAu100-x/CNF electrocatalysts exhibited improved electrocatalytic activities towards formic acid oxidation by providing the selectivity of the reaction via dehydrogenation pathway and suppressing the formation/adsorption of poisoning CO intermediate, indicating that PtxAu100-x/CNF is promising electrocatalyst in direct formic acid fuel cells.

A novel technique for NACE coupled with simultaneous electrochemiluminescence and electrochemical detection for fast analysis of tertiary amines

A simultaneous electrochemiluminescence (ECL) and electrochemical (EC) detection scheme for NACE was presented for fast analysis of tertiary amines. Both ECL and EC signals were generated at the same Pt electrode. Triethylamine (TEA), tripropylamine (TPrA), chlorpromazine, promethazine, and dioxopromethazine (DPZ) were selected to validate NACE-ECL/EC dual detection strategy. The linear ranges for TEA and TPrA were 0.01-500 and 0.01-10 mu M with the detection limits of 8.0 and 5.0 nM (S/N=3), respectively. The RSDs (n = 6) of the migration time and the ECL intensity for 1 mu M TEA and 0.5 mu M TPrA were 0.1 and 2.8%, and 0.2 and 1.8% with theoretical plate numbers of 180 000 and 700 000 per meter, respectively. These two analytes could be separated within 92 s and the Pt electrode did not need reactivation during the experiments.

A novel tris(2,2 '-bipyridine)ruthenium(II)/tripropylamine cathodic electrochemiluminescence in acetonitrile for the indirect determination of hydrogen peroxide

A novel tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)3(2+)) cathodic electrochemiluminescence (ECL) was generated at -0.78V at the Pt electrode in acetonitrile (ACN), which suggested that the cathodic ECL differed from conventional cathodic ECL It was found that tripropylamine (TPrA) could enhance this cathodic ECL and the linear range (log-log plot) was 0.2 mu M-0.2 mM. In addition, hydrogen peroxide (H2O2) could inhibit the cathodic ECL and was indirectly detected with the linear range of 27-540 mu M. The RSD (n = 12) of the ECL intensity in the presence of 135 mu M H2O2 was 0.87%. This method was also demonstrated for the fast determination of H2O2 in disinfectant sample and satisfactory results were obtained.

Nonenzymatic glucose sensor based on renewable electrospun Ni nanoparticle-loaded carbon nanofiber paste electrode

A novel nonenzymatic glucose sensor was developed based on the renewable Ni nanoparticle-loaded carbon nanofiber paste (NiCFP) electrode. The NiCF nanocomposite was prepared by combination of electrospinning technique with thermal treatment method. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that large amounts of spherical nanoparticles were well dispersed on the surface or embedded in the carbon nanofibers. And the nanoparticles were composed of Ni and NiO, as revealed by energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD). In application to nonenzymatic glucose determination, the renewable NiCFP electrodes, which were constructed by simply mixing the electrospun nanocomposite with mineral oil, exhibited strong and fast amperometric response without being poisoned by chloride ions. Low detection limit of 1 mu M with wide linear range from 2 mu M to 2.5 mM (R = 0.9997) could be obtained.

Enantioseparation of Dioxopromethazine Hydrochloride in Urine with Liquid-Liquid Extraction by CE-ECL Detection

Capillary electrophoresis coupled with electrochemiluminescence detection was developed for the separation and determination of dioxopromethazine hydrochloride (DPZ) enantiomers. Performance parameters of the proposed method were evaluated. An improved separation of DPZ enantiomers could be achieved after adding boric acid to buffer. The enantiomers were completely separated with running buffer of 16.5 mM beta-CD in 25 mM tris-H3PO4-40 mM H3BO3 at pH 2.5. The proposed method was successfully applied to the separation and determination of DPZ enantiomers in human urine with a liquid-liquid extraction procedure.