排序方式: 共有117条查询结果,搜索用时 15 毫秒
51.
Tahereh PoursaberiMorteza Hosseini Massoud TaghizadehHooshang Pirelahi Mojtaba ShamsipurMohammad Reza Ganjali 《Microchemical Journal》2002,72(1):77-83
A highly selective electrode for iodide ion based on a thiopyrilium derivative as an excellent ionophore is described. At pH 5.5-8.0, the electrode responds to iodide ion in a linear range from 1.0×10−1 to 8.0×10−7 M with a slope of 60.2 mV per decade, and a detection limit of 2.0×10−7 M. Selectivity coefficients determined with the match potential method (MPM) indicate that the interference from inorganic and organic anions is very small. The proposed sensor shows a fast response time of approximately 15 s. It was applied as an indicator electrode in titration of iodide with Ag+. 相似文献
52.
Afshin Rajabi Khorrami Tahereh Hashempur Ali Mahmoudi Ali Reza Karimi 《Microchemical Journal》2006,84(1-2):75-79
A highly sensitive and accurate method for preconcentration and determination of ultra trace amounts of cobalt and nickel ions in water samples is proposed. The preconcentration is achieved using C18-silica extraction disks modified with 5-(6-methoxy-2-benzothiazoleazo)-8-aminoquinoline (MBTAQ). The retained ions on the prepared solid phase was eluted with 10 ml of 0.01 M nitric acid and measured by inductively coupled plasma-optical emission spectrometry (ICP-OES). The influence of the type and amount of eluent used, pH, sample and eluent flow rates, amount of MBTAQ and the effect of other ions on extraction efficiency were investigated. The limits of detection of the method were 0.08 and 0.06 μg l− 1 for cobalt and nickel, respectively, and provide an enrichment factor of 100. The results obtained on 10 successive extractions and elution cycles revealed relative standard deviations of 1.5 and 1.0% for cobalt and nickel, respectively. The proposed method has been applied to the determination of ultra trace amounts of cobalt and nickel ions in natural and synthetic water samples with satisfactory results. 相似文献
53.
Marzieh Sadeghi Mohsen Irandoust Fatemeh Khorshidi Mostafa Feyzi Fataneh Jafari Tahereh Shojaeimehr Mojtaba Shamsipur 《Journal of the Iranian Chemical Society》2016,13(7):1175-1188
The application of newly synthesized Fe3O4/TiO2–SiO2 that is modified with zinc (FTSZ) as a sorbent, for the removal of arsenic from contaminated water has been investigated in the present study. SEM, FTIR, XRD, BET, Zeta potential sizer (ξ) analyses are used to determine the sorbent characterization. The effect of the operational parameters such as initial pH, initial concentration, and the contact time were studied. In addition, the equilibrium behavior of FTSZ in As(III) removal was investigated in the temperature range of 20–40 °C. The results showed that the equilibrium data were fitted well with Langmuir than Freundlich isotherm model. The maximum monolayer adsorption capacity estimated by Langmuir isotherm was 24.010 mg g?1. Thermodynamic parameters, ?H°, ?S° and ?G° were also calculated from graphical interpretation of the experimental data. Standard heats of sorption (?H°) were found to be endothermic and ?S° values were calculated to be positive for the sorption of As(III) onto the adsorbent. 相似文献
54.
Tahereh Hashempur Mohammad Kazem Rofouei Afshin Rajabi Khorrami 《Microchemical Journal》2008,89(2):131-136
A highly sensitive and accurate method for preconcentration and determination of ultra trace amounts of inorganic mercury and organomercury compounds in different water samples is proposed. The preconcentration is achieved using octadecyl silica (C18) extraction disks modified with 1,3-bis(2-cyanobenzene)triazene (CBT). The retained analytes as their triazenide complexes on the solid phase was eluted with 10 ml acetonitrile and measured by reversed-phase high-performance liquid chromatography (RP-HPLC). Type and amount of eluent, pH, amount of CBT, flow rates of sample solution and eluent have been optimized in order to obtain quantitative recovery of the analytes. The effect of interfering ions, such as Cu2+, Mn2+, Fe2+, Al3+, Zn2+, Cd2+, Ca2+, Mg2+, Ba2+, Pb2+, K+ and Na+ usually present in water samples on the recovery of the analytes has also been investigated. The enrichment factor of 100 was obtained for all mercury species and the analytical detection limits of phenylmercury, methylmercury and Hg2+ were found as 0.8, 1.0 and 1.3 ng l− 1, respectively. Stability of mercury species after extraction on the modified disks was studied and the results showed that complexes collected on the disks were stable for at least 5 days. The proposed method has been applied to the quantitative determination of mercury species in natural and synthetic water samples with recoveries more than 90%. 相似文献
55.
Tahereh Soleymani Ahooie Najmedin Azizi Issa Yavari Mohammad Mahmoudi Hashemi 《Journal of the Iranian Chemical Society》2018,15(4):855-862
A green, reliable synthetic method and highly efficient one-pot three-component synthesis of 2,4,5-trisubstituted imidazoles from 1,2-diketones, aldehydes and ammonium acetate in the presence of recyclable magnetic graphitic carbon nitride nanocomposite (Fe3O4@g-C3N4) has been developed. Various imidazole derivatives were obtained in moderate to excellent yields and high purity after recrystallization from ethanol. Interestingly, the low-cost Fe3O4@g-C3N4 a nontoxic and inexpensive catalyst showed excellent recyclability using an external magnet without loss of parent catalytic activity even after ten cycles and its provides new opportunities for the truly environmental friendliness methodology. 相似文献
56.
Ahooie Tahereh Soleymani Azizi Najmedin Hashemi Mohammad Mahmoudi Yavari Issa 《Research on Chemical Intermediates》2018,44(2):1425-1436
Research on Chemical Intermediates - A magnetic graphitic carbon nitride (g-C3N4) nanocomposite was prepared and used as a novel magnetically retrievable nanocatalyst for efficient ring opening of... 相似文献
57.
Numerical Algorithms - This paper is devoted to investigate the modified extended second derivative backward differentiation formulae from second derivative general linear methods point of view.... 相似文献
58.
A highly effective and mild protocol for ring opening of epoxides with NH 4 SCN in the presence of catalytic amount of a multisite phase-transfer catalyst, α,α',α" -N-hexakis(triethylammoniummethylene chloride)-melamine, is developed. A variety of b-hydroxy thiocyanates as important intermediates in agricultural and pharmaceutical chemistry were obtained in high yields with excellent regioselectivity and in short reaction times. 相似文献
59.
Five organotin(IV) complexes,were obtained by reaction of SnR2Cl2(R = Ph,Me,Bu) with ONO donor Schiff bases.The synthesized complexes have been investigated by elemental analysis and IR,1H NMR,and 119Sn NMR spectroscopy.These data show that the Schiff base acts as a tridentate dianionic ligand and coordinates via the imine nitrogen and two oxygen atoms.The Xray crystallography of complex 4 shows a dimeric structure for this molecule.The in vitro antibacterial activities of the Schiff bases and their complexes have been evaluated against Gram-positive(Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and compared with the standard antibacterial drugs. 相似文献
60.
In this article our aim was to evaluate mass cultivation of S. marianum hairy roots in a bioreactor to produce silymarin. The effects of methyl jasmonate (MJ) elicitation on the accumulation of silymarin and the extent of the MJ-induced oxidative damage were investigated in bioreactor hairy root cultures of S. marianum. The growth rate of the bioreactor hairy root cultures was higher than that of those in a shake flask after 3 weeks. Silymarin accumulation was increased from 0.13?mg?g?1 DW in non-treated hairy roots to 0.22?mg?g?1 DW in hairy roots 72?h after 100?μM?MJ treatment. Guaiacol peroxidase and ascorbate peroxidase were activated by MJ?72?h after treatment, being 3.2- and 1.3-fold higher, respectively, than that of the control. An increase in enzymatic activity suggests increased scavenging of reactive oxygen species, indicating the tolerance to MJ stress. These results suggest that MJ elicitation is beneficial for silymarin production using bioreactor hairy root cultures. 相似文献