Biomedical subjects

Jianbin Zheng

Publications and source records attributed to Jianbin Zheng.

6 recordsLinked to original sources

PubMed2006

Sodium dodecyl sulfate-modified carbon paste electrodes for selective determination of dopamine in the presence of ascorbic acid.

A carbon paste electrode (CPE) modified by a monolayer film of sodium dodecyl sulfate (SDS) was used for detection of dopamine (DA). Cyclic voltammetry demonstrated improved response of the DA sensor. This suggests the effectivity of surface modification of CPE by SDS. Impedance spectroscopy was used for the characterization of CPE surface properties. The effect of SDS concentration on the electrode quality also reveals that SDS formed a monolayer on CPE surface with a high density of negative-charged end directed outside the electrode. As a result, the carbon paste electrode modified with SDS (SDS/CPE) exerted discrimination against ascorbic acid in physiological circumstance. Thus, it can selectively determine dopamine even in the presence of 220-fold AA combined with differential pulse stripping voltammetry. In pH 7.40 phosphate buffer solution, the oxidation peak current on differential pulse voltammograms increases linearly with the concentration of DA in the range of 5.0 x 10(-7) to 8.0 x 10(-4) mol . L(-1) with a detection limit of 5.0 x 10(-8) mol . L(-1). Satisfying results are achieved when detecting the DA in injection and simulated biology sample.

Ascorbic Acid↗

PubMed2006

[Simultaneous determination of four compounds in Sanjing Shuanghuanglian Oral Liquid by high performance liquid chromatography-diode array detection-electrochemical detection].

Chlorogenic acid, caffeic acid, baicalin and luteolin in Sanjing Shuanghuanglian Oral Liquid were simultaneously detected and identified using a high performance liquid chromatography coupled with diode array detection and electrochemical detection (HPLC-DAD-ECD). The separation was performed on a Zorbax SB-C18 column (150 mm x 4.6 mm i. d., 5.0 microm). The mobile phase consisted of (A) methanol and (B) methanol-water-acetic acid (50: 50: 1, v/v/v) using a linear gradient elution of 2%A-3%A at 0-3 min, 3%A-25%A at 3-15 min, 25%A-80%A at 15-20 min. The flow rate was 0.8 mL/min. The DAD detection was used at 275 nm. The ECD detection was done at 0.7 V. The column thermostat set at 30 degrees C. The limits of detection of the 4 compounds were 1 mg/L for chlorogenic acid, 0.2 mg/L for caffeic acid, 9 mg/L for baicalin, 7 mg/L for luteolin. The average recoveries were between 96.6%-99.6% with relative standard deviations (RSDs) of 2.5%-4.1%. The method is simple, rapid, reproducible and accurate. It can be used for the routine analysis of the four compounds in Shuanghuanglian Oral Liquid.

Caffeic Acids↗

PubMed2005

Design, synthesis, and biological evaluation of the N-diarylalkenyl-piperidinecarboxylic acid derivatives as GABA uptake inhibitors (I).

Twenty novel N-diarylalkenyl-piperidinecarboxylic acid derivatives were synthesized and evaluated as gamma-aminobutyric acid uptake inhibitors. The biological assay showed that (R)-1-[4,4-bis(3-phenoxymethyl-2-thienyl)-3-butenyl]-3-piperidinecarboxylic hydrochloride possessed almost as strong GAT1 inhibitory activity as tiagabine. The synthesis and structure-activity relationships are discussed.

Animals↗

PubMed2005

[Analysis of four components in Fufang Danshen Tablets by high performance liquid chromatography with electrochemical and ultraviolet detections].

A rapid and accurate method for the simultaneous separation and determination of protocatechuic acid, protocatechuic aldehyde, caffeic acid and tanshinone II A in Fufang Danshen Tablets by high performance liquid chromatography has been established. The former three constituents were detected by electrochemical array detector (ECD) and the last one by ultraviolet diode array detector (DAD). The separation was performed on a Zorbax SB-C18 column (150 mm x 4.6 mm i.d., 5.0 microm) by gradient elution with methanol and 0.4% aqueous phosphoric acid as mobile phase at a flow rate of 1.0 mL/min. The detections were done at 0.7 V, 270 nm and 30 degrees C. The results showed that the linear ranges were 0.3 - 9.0 mg/L for protocatechuic acid, 1.1 - 54.0 mg/L for protocatechuic aldehyde, 1.1 - 11.1 mg/L for caffeic acid and 5.2 - 52.0 mg/L for tanshinone II A. The average recoveries (n = 6) were 97.8% with relative standard deviation (RSD) of 2.15% for protocatechuic acid, 98.2% with RSD of 2.07% for protocatechuic aldehyde, 97.6% with RSD of 2.18% for caffeic acid and 97.2% with RSD of 2.07% for tanshinone II A. These four components were separated successfully from each other. The sensitivities of detection of protocatechuic acid, protocatechuic aldehyde and caffeic acid with ECD were 11.0 - 25.3 times greater than those with DAD. The study provides a scientific basis for the quality control of Fufang Danshen Tablets.

Abietanes↗

PubMed2003

Voltammetric behavior of 4',7-dimethoxy-3'-isoflavone sulfonic sodium and its enhancement determination in the presence of surfactant.

Voltammetric behavior of 4',7-dimethoxy-3'-isoflavone sulfonic sodium (DISS) was studied by linear sweep voltammetry and cyclic voltammetry. DISS caused two waves between pH 8.0 and 12.0. Above pH 8.0, the peak current of first wave Pc1 of DISS was enhanced in the presence of cetyltrimethylammonium bromide (CTAB). Based on this, a novel method for the determination of DISS was proposed. In Britton-Robinson buffer solution (pH 11.7) containing 9.4 x 10(-6)mol L(-1) CTAB, the peak potential of first wave Pc1 of DISS was -1.59 V (vs standard saturated calomel electrode) and its first-order derivative peak current was proportional to the concentration of DISS in the range 5.0 x 10(-8)-6.0 x 10(-7)mol L(-1) (r=0.998). The detection limit was 1 x 10(-8)mol L(-1), which was 10 times lower than that of the corresponding reduction wave. The method was applied to the determination of DISS in synthetic samples.

Electrochemistry↗

PubMed2003

Genetic algorithms based on wavelet transform for resolving simulated overlapped spectra.

Wavelet transform-based genetic algorithms are proposed for resolving simulated overlapped spectra. Wavelet transform as a derivative method is used for de-noising, for deducting background absorption as well as for peak finding in order to get an estimation of parameters of unresolved spectra. Then genetic algorithms, using the estimations of parameters as input values, are employed to resolve unresolved bands. As a consequence, a good optimized solution was achieved since the reliable estimation of initial values can greatly facilitate the convergence of genetic algorithms and the calculation time is shortened accordingly.

Journal Article↗