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ABSTRACT: A new capillary zone electrophoresis method with laser-induced fluorescence detection is presented for the determination of
noradrenaline (NA) and dopamine (DA). The fluorescent reagent, 5-(4,6-dichloro-s-triazin-2-ylamino) fluorescein, which readily
reacts with amine group under mild conditions, was initially used to label the two compounds. Under optimized separation and
labeling conditions, linear relationship between peak area and analyte concentration was obtained with high sensitivity (nM
level). The applicability of the method for complex sample analysis was validated by determining the two compounds in a human
serum and an herb, Portulaca oleracea L with recoveries ranging from 89% to 102%.
Microchimica Acta 04/2012; 166(3):289-294. · 3.03 Impact Factor
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ABSTRACT: Some categories of compounds, including quinones, coumarins, flavins, and xanthene dyes, were found to produce strong chemiluminescence (CL) signals with luminol in sample solution under the irradiation of light emitting diodes (LED) with proper wavelengths. Based on this phenomenon, a compact photochemical reactor was constructed to develop a novel LED induced CL detector for high performance liquid chromatography (HPLC). The effects of related parameters including LED wavelength, luminol concentration, flow rate, pH, and eluents of HPLC were investigated in detail. Under the optimized conditions, the limits of detections (LODs) were in the range of 0.2-80 ng mL(-1). The applications and accuracy of the proposed method were validated by analyzing food samples such as milk powder, beer, candy and beverage with satisfactory results.
Journal of chromatography. A 10/2009; 1216(51):8926-32. · 4.19 Impact Factor
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ABSTRACT: On the basis of the coarse grained model, we investigated the adsorption of nonuniformly charged fullerene-like nanoparticles on planar polyelectrolyte brushes (PEBs) in aqueous solution by using Brownian dynamics simulation. It is found that the electroneutral nanoparticles can be adsorbed by the PEB, which is attributed to the asymmetrical electrostatic interactions of the PEB with the positively charged sites and negatively charged sites of the fullerene-like nanoparticles. The simulation results indicated that the adsorption amount exhibits non-monotonic behavior with the dipole moment of nanoparticles. First, the adsorption amount increases with the dipole moment and then reaches the maximum at the dipole moment of micro = 10.45. Finally, the adsorption falls at the dipole moment of micro = 14.39. The reason may be that, at the extremely large dipole moment of micro = 14.39, the fullerene-like nanoparticles aggregate together to form a big cluster in the bulk phase, which can be confirmed by the extremely high peak in the radial distribution function between nanoparticles. Accordingly, it is difficult for nanoparticles to enter into the PEB at the dipole moment of micro = 14.39. In addition, it is also found that the brush grafting density is an important factor affecting the brush thickness.
Langmuir 04/2009; 25(9):4965-72. · 4.19 Impact Factor
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ABSTRACT: Derivative spectrophotometry is introduced for the quantification of overlapping peaks in capillary electrophoresis. The application
for resolving overlapping peaks is tested using eleven benzoic acids as examples. Compared with common spectrophotometric
detection, the derivative mode has slightly lower reproducibility, comparable sensitivity but much higher separation efficiency
as the peak is much sharpened. Derivative spectrophotometry offers the advantages of reagent-, time- and labor-saving since
only few optimizations of separation conditions for normal CE are essential to make the peaks partly baseline-resolved. Analysis
of real samples using the method was also performed and results obtained give evidence of the potential for improved quantification
without loss in accuracy.
Microchimica Acta 02/2009; 164(3):487-491. · 3.03 Impact Factor
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ABSTRACT: A Brownian dynamics (BD) simulation is performed to investigate the effect of the bridging conformation of a polyelectrolyte (PE) with two charged heads (two-heads PE) on the radial distribution function (RDF) and diffusion behavior of macroions on the basis of the coarse grained model. For comparison, the system containing macroions and the PE with only one charged head (one-head PE) is also investigated. The simulation results indicate that, at low concentrations, the bridging effect of the two-heads PE chain leads to correlation of macroions. The reason is that at low concentration the gyration radius of the PE chain is less than the average distance between two macroions. When the two-heads PE chains are adsorbed on different macroions, the bridging effect of the PE chain dominates the RDF and diffusion behavior of the macroions. With the increase of the concentration of the system, when the gyration radius of the PE chain is greater than the average distance between two macroions, the bridging effect of the PE chain becomes trivial. By investigating the mechanism of the two-heads PE chain affecting the static and dynamic properties of the macroions, we can provide useful information for the synthesis of stabilizers and destabilizers of colloidal particles.
Langmuir 10/2008; 24(18):10138-44. · 4.19 Impact Factor
