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Rutin,a flavonoid found in fruits and vegetables,is a potential anticancer compound with strong anti-cancer activity.Therefore,electrochemical sensor was developed for the detection of rutin.In this study,CoWO4 nanosheets were synthesized via a hydrothermal method,and porous carbon(PC)was prepared via high-temperature pyrolysis.Successful preparation of the materials was confirmed,and character-ization was performed by transmission electron microscopy,scanning electron microscopy,and X-ray photoelectron spectroscopy.A mixture of PC and CoWO4 nanosheets was used as an electrode modifier to fabricate the electrochemical sensor for the electrochemical determination of rutin.The 3D CoWO4 nanosheets exhibited high electrocatalytic activity and good stability.PC has a high surface-to-volume ratio and superior conductivity.Moreover,the hydrophobicity of PC allows large amounts of rutin to be adsorbed,thereby increasing the concentration of rutin at the electrode surface.Owing to the syn-ergistic effect of the 3D CoWO4 nanosheets and PC,the developed electrochemical sensor was employed to quantitively determine rutin with high stability and sensitivity.The sensor showed a good linear range(5-5000 ng/mL)with a detection limit of O.45 ng/mL.The developed sensor was successfully applied to the determination of rutin in crushed tablets and human serum samples.
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Carbon nanosheets load beta-cyclodextrin (β-CD-CNS) as a new modified electrode materials was reported for the electrochemical determination of sulfadiazine(SD). Carbon nanosheets(CNS) were prepared by a new method of ultrasonic electrolysis in which the β-CD was attached on CNS through ultrasonic dispersion method. The β-CD-CNS composite nanomaterials were immobilized onto glassy carbon electrodes with drops of coating method to construct an SD voltammetric sensor. The differential pulse stripping voltammetry (DPSV) was used to characterize the electrocatalytic behavior of the developed sensor. The Effects of some parameters on the response behavior of the sensor such as pH,modification amount,scanning rate,stirring speed,stirring time,deposition potential and time were investigated and optimized. The results indicated that the β-CD-CNS composite nanomaterials had excellent electroactivity for the SD in neutral solution and greatly improved the current response of SD. Under the optimal conditions, the SD had an irreversible characteristic oxidation peak around+0.87 V,and the oxidation peak current ip(μA) had a good linear relationship with the concentration C ( μmol/L) of the SD in concentration range of 0.05 μmol/L-13.5 μmol/L with correlation coefficients of 0.999. The detection limit was 12.2 nmol/L (S/N=3). The sensor was successfully applied for the trace SD determination in water and milk samples and the recoveries from the spiked samples were 80.0%-102% with RSD≤5.2%.
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Acute traumatic spinal cord injury (SCI) represents one of the most devastating injuries that afflict the human body. Ascorbic acid ( AA) plays an important role in mammalian central nervous system, especially in SCI. In this study, the change of AA concentration after SCI was investigated by using an on-line electrochemical method integrated with in vivo microdialysis. A microdialysis probe (2 mm in length) was implanted into the spinal cord of an anesthetized rat (Thoracic-10). Microdialysis perfusate (2 μL/ min) was collected in the sample loop of an on-line injector for direct injection onto a glassy carbon electrode which was modified with the heat-treated single-walled carbon nanotubes (SWNTs). Normal ascorbic acid concentration in the extracellular fluids of spinal cords was (26. 17 ± 1. 25) μmol/ L (n =8). The experimental spinal cord injury, induced by a lesion at T-10, significantly increased the extracellular ascorbic acid levels to (53. 24± 1. 95) μmol/ L (n =8). This study provides the experimental evidence on the essential roles of ascorbic acid in spinal cord injuries.
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High performance liquid chromatography-electrochemical detection (HPLC-ED)is an important analytical tool for the determination of pharmaceutical drugs since electrochemical detectors provides derivertization-free, sensitive, selective, and low cost detection methods. Numerous papers and reviews have been published since the HPLC-ED techniques were introduced forty years ago. This article will review the electrochemical instruments and detection methods used in HPLC, and focus on recent advances in the analysis of pharmaceutical drugs using HPLC-ED techniques, and discuss the future development trend of the techniques.
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A simple and green method for the determination of trace bisphenol A( BPA) was established by coupling supported ionic liquid solid phase extraction to β-cyclodextrin modified ionic liquid carbon paste electrode-based electrochemical detection ( SILs-SPE-ED) . The synthesized imidazolium ionic liquid modified styrene type macroporous resin was used as adsorbent for SPE of BPA. The critical parameters that affect the extraction efficiency were optimized, including 0. 4 g of packing material quantity, 200 mL of sample solution at pH 7. 0, 5 mL of methanol as an eluent solvent, and 4. 5 mL/min of the SPE flow rate. Dynamic adsorption test showed that the maximum adsorption capacity of BPA on the SILs-SPE cartridge was 10. 1 mg/g, and the enrichment factor was 40 . The calibration curve showed a good linearity between the anodic current and the BPA concentration in the range of 1. 0×10-8-1. 0×10-6 mol/L (i. e. 2. 3-228μg/L). The detection limit was 4. 16×10-9 mol/L (equal to 0. 95 μg/L). The SILs-SPE-ED method was applied to the analysis of water and plastic samples and the results agreed well with HPLC method.
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A microfluidic chip with integrated microelectrode for real-time dopamine detection was designed and fabricated. The chip consisted of a polydimethylsiloxane ( PDMS) channel plate and a glass electrode plate. One central channel as the culture chamber of neural stem cells and two lateral channels for transport of the culture medium were integrated on the PDMS channel plate. Microelectrodes for real-time dopamine detection were integrated on the glass electrode plate. To solve the problem in demoulding the PDMS channel plate from the silicon mould, a novel demoulding method was developed. An Au-Au-Au three-electrode system was constructed, and it performed well in electrochemical detection. The performance of the microfluidic chip was primarily studied by detecting dopamine dissolved in the medium for the culture of neural stem cells. The limit of detection was 3. 92 μmol/L, the linear detection range was from 10 μmol/L to 500 μmol/L, and the detection reproducibility from different chips was less than 4%.
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A novel method for analysis of three active components curcumin, demethoxycurcumin and bisdemethoxycurcumin in Curcuma longa L. was developed by HPLC coupled with electrochemical detection. Three curcuminoids were well separated on a C18 column and detected with high sensitivity. A mobile phase containing acetonitrile and 10 mM Na2HPO4-H3PO4 (pH 5.0) (50:50, v/v) was used. Good linearity was obtained in the range of 0.208-41.6, 0.197-39.4, and 0.227-114μM for curcumin, demethoxycurcumin and bisdemethoxycurcumin respectively. The limit of detection reached up to 10 ? 8 M, which was lower than that by UV detection. The relative standard deviations (RSDs) ranged from 1.06%to 1.88%for intra-day precision and from 4.30%to 5.79%for inter-day precision, respectively. The proposed method has been applied in real herb sample and recoveries ranging from 86.3%to 111%were obtained.
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Objective To investigate the change of glucose metabolism in warm ischemia/reperfusion injured kidney of rabbits in vivo by microdialysis and real-time electrochemical detection.Methods A total of 20 New Zealand rabbits were divided into experiment and control groups(10 in each).After anesthesia by intravenous injection of barbitone,an oblique incision under the 12th rid was made in the animals to expose the right kidney and the right renal artery and vein.Afterwards,a microdialysis probe was placed into the dorsal renal cortex along the long axle of the kidney.After 60 minutes to equilibrate,an electrochemical detection system was used to continuously determine the concentration of glucose in the renal cortex before ischemia.Then,ischemia/reperfusion injury model was established by clamping the renal pedicle for 60 minutes followed by perfusion for 60 minutes.The control group received the same intervention without clamping the renal pedicle.The glucose concentration of the microdialysis samples were analyzed before,during,and after the ischemia.Results The reaction of the glucose electrode to the electric current was linearly correlated with the concentrations of glucose,and the rate of microdialysis probe recycling was(63.6?2.1)%.The concentration of glucose in the renal cortical interstitial samples were(1.89?0.37),(0.69?0.12),and(0.62?0.14)mmol/L respectively before,during,and after the warm ischemia.During the ischemia phase,the mean concentration of glucose decreased by(36.7?2.4)% from the base level(LSD test,P=0.000).The glucose concentration of the experimental group was significantly lower than that in the control at both ischemia and reperfusion phases(t=-11.975,P=0.000;t=-11.993,P=0.000,respectively).Conclusions In vivo microdialysis combined with electrochemical detection provides a sensitive and real-time method for measuring the glucose concentration in warm ischemia/reperfusion injured kidney,which can suggest the ischemic condition of the renal cortex.
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OBJECTIVE：To study the secretion of catecholamine primary cultures of chromaffin cells from rat adrenal medulla were used.METHOD:Catechoalmines(norepinephrine,epinephrine and dopamine) were measured by high-performance liquid chromatography-electrochemical detection technique.RESULTS:Catecholamine released by chromaffin cells with in 20min without slimalus was (73.29±15.32) ng/106 cells.When acetylcholine,nicotine or muscarine was added,the secretion of catecholamine was then increased.CONCLUSION:Using high-performance liquid chromatography-electrochemical detection technique,we can detect sensitively catecholamine released by cultured rat chromaffin cells.
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A rapid and simple chromatographic procedure using HPLC-ECD is described for simultaneousdetermination of NE. E. DA. 5-HT with their precursor amino acid (Tyr. Trp) and their main metabolites (HVA. 5-HIAA). Using this assay,eight substrates are measured in cortex, diencephalon and brain stem of mice duing immunological response challenged by SRB6 3 days after challenged, the DA HVA in cortex, NE in diencephalon decrease obviously (p
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Objective: The method for separation by capillary zone electrophoresis (CZE) and electrochemical determination of organic acids in fruit juices was developed. Method: In this system, 0.2mmol/L cetylpyridinium bromide (CPB) was used as an electro osmotic flow (EOF) modifier to reverse the direction of EOF. cyclodexfrin ( -CD) was added into running buffer to improve the separation efficiency. Then, the optimal separation conditions were achieved and successfully employed to separate six organic acids, including oxalic, malic, tartaric, succinic, fumaric acid and citric acids. One nano palladium modified carbon paste electrode was used for determination. Results: The calibration curves for all organic acids studied were linear with 2-3 orders (1 10–6-1.0 10–3 mol/L) of magnitude and all the detection limits (S/N=3) were below 2 mol/L. The RSD was between 1.05%-2.15% , and recovery was 93.4% . Conclusion: CZE separation combined with electrochemical detection is suitable for simultaneous determination of organic acids in fruit juices quickly with high sensitivity and selectivity.