ABSTRACT
Highly conjugated linear molecular wires are one of the basic elements for constructing molecular electronic devices. Among these conjugated compounds, ferrocene-terminated compounds as well as their derivatives have been widely studied because of their ideal electrochemical activity. Based on these, a new ferrocene-terminated phenylethynyaniline ( Fc-NH2 ) was synthesized by Sonogashira cross coupling reaction. The structure of the target compound was identified by infrared ( IR) , nuclear magnetic resonance ( NMR) , mass spectra ( MS) and cyclic voltammetry ( CV) . Combined the graphene-chitosan ( GH-CS) and Fc-NH2 , a new composite of GH-CS/Fc-NH2 was prepared and then used for immobilization of Cytc to prepare the GH-CS/Fc-NH2/Cytc/GCE. It was found from the CV result that a pair of peaks near-0. 2 V appeared which can be attributed to Cytc. The GH-CS/Fc-NH2/Cytc modified GCE showed good catalysis towards NaNO2 , and good linear relationship was found in the range of 1 ×10-7-1. 5 ×10-4 mol/L,and the determination limit was bellow 4×10-8 mol/L. Therefore, cytochrome c (Cytc) can be immobilized on the GH-CS/Fc-NH2 and the direct electron transfer can be realized between the electrode and solution and shows good prospect for detection of NaNO2 .
ABSTRACT
A high-performance liquid chromatography method was developed for determination of five nucleotides in Bulbus Fritillariae. The five nucleotides were uridine, adenine, guanosine, thymidine, adenosine, respectively. A Welch materials XB-C18 column (4.6 mm x 250 mm, 5 microm) was used and the chromatographic separation was achieved using 5 mmoL x L(-1) ammonium acetate-acetic acid buffer solution (pH 4.30, B) and methanol (A) as mobile phases, the gradient elution program: 0-10 min, 0%-1% A, 10-20 min, 1%-5% A, 20-25 min, 5% A, 25-35 min, 5%-30% A, 35-37 min, 30%-0% A, 37-40 min, 0% A with a flow rate of 1 mL x min(-1) and monitored at 260 nm, the injection volume was 20 microL. The peak areas of nucleotides and the concentrations showed a good linear relation ranged from 0.24 to 13.60 mg x L(-1), r > 0.9983. The intra- and inter-day pecision results were adequate with the RSDs of 2.1% or below. The repeatability was good and the RSD were smaller than 5.5%. The recoveries of nucleosides were in the range of 93.55% and 101.9%, RSD < 3.0%; The order of nucleotides contents in different Bulbus Fritillariae was F. hupehensis > F. thunberqii > F. cirrhosa approximately F. ussuriensis. The method is simple, convenient and accurate. It can be used for the determination of nucleosides and supplying evidence for exploiting and applying of Bulbus Fritillariae.
Subject(s)
Chromatography, High Pressure Liquid , Methods , Drugs, Chinese Herbal , Chemistry , Fritillaria , Chemistry , Nucleotides , Chemistry , Reproducibility of ResultsABSTRACT
A novel molecularly imprinted polymers (MIPs) was prepared based on multiwalled carbon nanotubes (MWNTs) by using chlorogenic acid as template, methacrylic acid(MAA) as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. Infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis were employed to characterize the composite structure and morphology, the results showed that a stable imprinted layer was grafted on the MWNTs with the average thickness of 30-40 nm. The dynamic adsorption and static adsorption experiments were also executed and the results showed that two kinds binding sites with the maximum apparent binding constant 21.5 μmol/g and 32.7 μmol/g existed v.i. between the imprinted polymers and chlorogenic acid. As solid phase extraction (SPE) materials, the separation and enrichment of chlorogenic acid from honeysuckle were successful with a enrichment factor of 25.
ABSTRACT
Object To determine the amount of cichoric acid in Enchinacea purpurea and its preparation. Methods By the use of HPLC, mobile phase: 400 mmol/L ammonium acetate methanol (95∶ 5), flow rate: 1 mL/min, detection wavelength: 330 nm. Results The mean recovery of cichoric acid was 99 41%, RSD=3 23% (n=5). Conclusion The method can be applied in the determination of cichoric acid in E. purpurea extract and its preparation with satisfactory results.
ABSTRACT
Object To establish an isolation method of theanine reference substance by preparative HPLC. Methods After raw material extracted by water, the water phase was extracted by chloroform saturated with water, then concentrated on a thermostat. After centrifuged, supernatant was isolated and purified by preparative HPLC. Fraction was frozen and dried by Flexi Drier. Crude product was rinsed by methanol. The purity of product was determined by analytical HPLC. Results The purity of product is higher than 98% and theanine yield from raw material by this method exceeds 60%. Conclusion The developed method is simple, rapid, and at low production cost. The product owns the quality of reference substance.