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971.
Construction of Modified Carbon Paste Electrode for Highly Sensitive Simultaneous Electrochemical Determination of Trace Amounts of Copper (II) and Cadmium (II) 下载免费PDF全文
Abbas Afkhami Morteza Soltani‐Shahrivar Hamed Ghaedi Tayyebeh Madrakian 《Electroanalysis》2016,28(2):296-303
A chemically modified electrode was constructed for rapid, simple, accurate, selective and highly sensitive simultaneous determination of Cu(II) and Cd(II) using square wave anodic stripping voltammetry. The electrode was prepared by incorporation of SiO2 nanoparticles, coated with a newly synthesized Schiff base, in carbon paste electrode. The limit of detection was found to be 0.28 ng mL?1 and 0.54 ng mL?1 for Cu(II) and Cd(II), respectively. The proposed chemically modified electrode was used for the determination of copper and cadmium in several foodstuffs and water samples. 相似文献
972.
Carbon Paste Electrode Modified with Biochar for Sensitive Electrochemical Determination of Paraquat 下载免费PDF全文
Cristiane Kalinke Antonio S. Mangrich Luiz H. Marcolino‐Junior Márcio F. Bergamini 《Electroanalysis》2016,28(4):764-769
The present work reports for the first time the determination of paraquat (PQ2+) by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV) using a carbon paste electrode modified (CPME) with biochar obtained from castor oil cake at different temperatures (200–600 °C). The best voltammetric response was verified using biochar yielded at 400 °C (CPME‐BC400). Linear dynamic range (LDR) for PQ2+ concentrations between 3.0×10?8 and 1.0×10?6 mol L?1 and a limit of detection (LOD) of 7.5×10?9 mol L?1 were verified. The method was successfully applied for PQ2+ quantification in spiked samples of natural water and coconut water. 相似文献
973.
Mario A. Saucedo‐Espinosa Mallory M. Rauch Alexandra LaLonde Blanca H. Lapizco‐Encinas 《Electrophoresis》2016,37(4):635-644
The relative polarization behavior of micron and submicron polystyrene particles was investigated under direct current and very low frequency (<1 kHz) alternating current electric fields. Relative polarization of particles with respect to the suspending medium is expressed in terms of the Clausius–Mossotti factor, a parameter of crucial importance in dielectrophoretic‐based operations. Particle relative polarization was studied by employing insulator‐based dielectrophoretic (iDEP) devices. The effects of particle size, medium conductivity, and frequency (10–1000 Hz) of the applied electric potential on particle response were assessed through experiments and mathematical modeling with COMSOL Multiphysics®. Particles of different sizes (100–1000 nm diameters) were introduced into iDEP devices fabricated from polydimethylsiloxane (PDMS) and their dielectrophoretic responses under direct and alternating current electric fields were recorded and analyzed in the form of images and videos. The results illustrated that particle polarizability and dielectrophoretic response depend greatly on particle size and the frequency of the electric field. Small particles tend to exhibit positive DEP at higher frequencies (200–1000 Hz), while large particles exhibit negative DEP at lower frequencies (20–200 Hz). These differences in relative polarization can be used for the design of iDEP‐based separations and analysis of particle mixtures. 相似文献
974.
The in‐capillary DPPH‐capillary electrophoresis‐the diode array detector combined with reversed‐electrode polarity stacking mode for screening and quantifying major antioxidants in Cuscuta chinensis Lam 下载免费PDF全文
Jiao Liu Ji Tian Jin Li John Teye Azietaku Bo‐li Zhang Xiu‐mei Gao Yan‐xu Chang 《Electrophoresis》2016,37(12):1632-1639
An in‐capillary 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH)‐CE‐the DAD (in‐capillary DPPH‐CE‐DAD) combined with reversed‐electrode polarity stacking mode has been developed to screen and quantify the active antioxidant components of Cuscuta chinensis Lam. The operation parameters were optimized with regard to the pH and concentration of buffer solution, SDS, β‐CDs, organic modifier, as well as separation voltage and temperature. Six antioxidants including chlorogenic acid, p‐coumaric acid, rutin, hyperin, isoquercitrin, and astragalin were screened and the total antioxidant activity of the complex matrix was successfully evaluated based on the decreased peak area of DPPH by the established DPPH‐CE‐DAD method. Sensitivity was enhanced under reversed‐electrode polarity stacking mode and 10‐ to 31‐fold of magnitude improvement in detection sensitivity for each analyte was attained. The results demonstrated that the newly established in‐capillary DPPH‐CE‐DAD method combined with reversed‐electrode polarity stacking mode could integrate sample concentration, the oxidizing reaction, separation, and detection into one capillary to fully automate the system. It was considered a suitable technique for the separation, screening, and determination of trace antioxidants in natural products. 相似文献
975.
Antimicrobial properties of biosynthesized silver nanoparticles studied by flow cytometry and related techniques 下载免费PDF全文
Viorica Railean‐Plugaru Pawel Pomastowski Katarzyna Rafinska Magdalena Wypij Wojciech Kupczyk Hanna Dahm Marek Jackowski Boguslaw Buszewski 《Electrophoresis》2016,37(5-6):752-761
This work reports the effect of silver bionanoparticles (Bio(AgNPs) synthesized by Actinobacteria CGG 11n on selected Gram (+) and Gram (–) bacteria. Flow cytometry, classical antibiogram method and fluorescent microscopy approach was used for evaluation of antimicrobial activity of Bio(AgNPs) and their combination with antibiotics. Furthermore, the performed research specified the capacity of flow cytometry method as an alternative to the standard ones and as a complementary method to electromigration techniques. The study showed antibacterial activity of both BioAgNPs and the combination of antibiotics/BioAgNPs against all the tested bacteria strains in comparison with a diffusion, dilution and bioautographic methods. The synergistic effect of antibiotics/BioAgNPs combination (e.g. kanamycin, ampicillin, neomycin and streptomycin) was found to be more notable against Pseudomonas aeruginosa representing a prototype of multi‐drug resistant “superbugs” for which effective therapeutic options are very limited. 相似文献
976.
Sami El Deeb Hermann Wätzig Deia Abd El‐Hady Cari Sänger‐van de Griend Gerhard K. E. Scriba 《Electrophoresis》2016,37(12):1591-1608
This review updates and follows‐up a previous review by highlighting recent advancements regarding capillary electromigration methodologies and applications in pharmaceutical analysis. General approaches such as quality by design as well as sample injection methods and detection sensitivity are discussed. The separation and analysis of drug‐related substances, chiral CE, and chiral CE‐MS in addition to the determination of physicochemical constants are addressed. The advantages of applying affinity capillary electrophoresis in studying receptor–ligand interactions are highlighted. Finally, current aspects related to the analysis of biopharmaceuticals are reviewed. The present review covers the literature between January 2013 and December 2015. 相似文献
977.
Two new nortriterpenoids, paeonenoides D and E ( 1 and 2 , resp.), together with seven known compounds, were isolated from the roots of Paeonia lactiflora. Their structures were elucidated on the basis of spectroscopic evidence. Compounds 1 – 7 were screened for inhibitory effects against NO production in LPS‐induced RAW246.7 macrophages and for cytotoxic activities against HL‐60, Hep‐G2, and SK‐OV‐3 cell lines. Compounds 1 – 3 and 5 – 7 exhibited inhibitory activities with IC50 values in the range of 9.6–32.2 μM . Triterpenoids with an epoxide ring and a free COOH function, 1 – 3 , showed effectively increased activities compared with other pentacyclic triterpenoids. Compounds 1 – 6 showed significant cytotoxic activities against the Hep‐G2 cell line and modest cytotoxic activities against HL‐60 and SK‐OV‐3 cell lines. 相似文献
978.
Synthesis and Cytotoxic Evaluation of Novel 1,2,3‐Triazole‐4‐Linked (2E,6E)‐2‐Benzylidene‐6‐(4‐nitrobenzylidene)cyclohexanones 下载免费PDF全文
Mohammad Mahdavi Maryam Akhbari Mina Saeedi Maryam Karimi Niloufar Foroughi Elahe Karimpour‐Razkenari Heshmatollah Alinezhad Alireza Foroumadi Abbas Shafiee Tahmineh Akbarzadeh 《Helvetica chimica acta》2016,99(3):175-180
This work describes the synthesis of novel 1,2,3‐triazole‐4‐linked (2E,6E)‐2‐benzylidene‐6‐(4‐nitrobenzylidene)cyclo‐hexanones starting from cyclohexanone. 1‐(Cyclohex‐1‐en‐1‐yl)piperidine, the enamine from cyclohexanone and piperidine, reacted with 4‐nitrobenzaldehyde to obtain 2‐(4‐nitrobenzylidene)cyclohexanone. Condensation of the latter compound with (prop‐2‐yn‐1‐yloxy)benzaldehyde derivatives under acidic conditions gave (4‐nitrobenzylidene)‐[(prop‐2‐yn‐1‐yloxy)‐benzylidene]cyclohexanones. Finally, ‘click reaction’ of these derivatives and various organic azides led to the title compounds. All compounds were examined by MTT assay for cytotoxic activity in one human breast cancer cell line, MDA‐MB‐231. 相似文献
979.
Three new Lycopodium alkaloids, fargesiines A – C ( 1 – 3 , resp.), along with a known compound ( 4 ), were isolated from the whole plants of Phlegmariurus fargesii. Their structures were elucidated on the basis of spectroscopic data and chemical correlations. Compounds 1 – 4 were tested in an assay for acetylcholinesterase (AChE) inhibitory activity. 相似文献
980.
Anti‐Inflammatory Activity of a Novel Acetylene Isolated from the Roots of Angelica tenuissima Nakai
Hyun Gyu Choi Hyukjae Choi Jeong‐Hyung Lee Byung Sun Min Jeong Ah Kim 《Helvetica chimica acta》2016,99(6):447-451
Three polyacetylenes, one novel and two known, were isolated from the root of Angelica tenuissima. Using 1H‐ and 13C‐NMR, COSY, HMBC, and HMQC, their structures were found to be (3R,8S)‐heptadeca‐1‐en‐4,6‐diyne‐3,8‐diol ( 1 ), falcarindiol ( 2 ), and oplopandiol ( 3 ). Absolute configurations of compound 1 were established using Mosher's esterification. In addition, the polyacetylenes ( 1 – 3 ) were evaluated for their anti‐inflammatory activity. Compounds 1 and 3 showed potent inhibitory activity against lipopolysaccharide‐induced nitric oxide (NO) production in RAW267.7 macrophage cells with IC50 values of 4.31 and 5.06 μm, respectively. Compound 1 strongly inhibited inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)‐2 in a concentration‐dependent manner. 相似文献