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91.
Bahram Hasani Abbasali Zamani Mahdieh Koorepazan Moftakhar Maryam Mostafavi Mohammad Reza Yaftian Massomeh Ghorbanloo 《Journal of Analytical Chemistry》2018,73(1):82-90
Bis(2-hydroxybenzaldehyde)-1,2-diaminoethane (LI), bis(2-hydroxybenzaldehyde)-1,3-diaminopropane (LII) and bis(2-hydroxybenzaldehyde)-4,4'-methylendianiline (LIII) were examined as ionophores for fabrication of polyvinylchloride (PVC) membrane Cu(II) ion-selective potentiometric sensors. The optimum composition (%) for the sensors was: 5 LI, 30 PVC, 6 sodium tetraphenylborate (NaTPB), 59 ortho-nitrophenyloctyl ether (NPOE); 4 LII, 30 PVC, 5 NaTPB, 61 dibutyl phthalate; 6 LIII, 30 PVC, 5 NaTPB, 59 NPOE. The linear response range of the electrodes was 5 × 10–4–0.05 (LI), 5 × 10–4–0.1 (LII) and 1 × 10–6–0.01 M (LIII), and the corresponding detection limits were 4 × 10–4, 4 × 10–4 and 2 × 10–7 M, respectively. The sensors were showed rapid response time (≈10 s). Their responses were independent on pH in the range 2.5–5.0 (LI), 3.2–4.7 (LII) and 4.0–5.0 (LIII). The selectivity of the prepared electrodes towards copper ions over some mono-, di- and trivalent metal ions was evaluated. The sensors were used as indicator electrode in potentiometric titration of copper ions in aqueous solutions. 相似文献
92.
Parisa Izadiyan Bahram Hemmateenejad S. Mohsen Taghavi Mahsa Izadiyan 《Journal of the Iranian Chemical Society》2018,15(2):259-268
Local names are not reliable sources for identification of plants, because they differ significantly from one region to another. Apart from confusing nomenclature, the similar appearance and fragrance of Shirazi thyme and Thymus species cause misidentification. In order to prevent the adverse events in relation to the use of improper herbal products, easy-to-use quality control (QC) methodology was developed to classify these culinary plants. Fourier transform infrared (FT-IR) fingerprinting technique was applied for classification of these plants on the basis of their biochemical compositions. Powerful PLS-DA classification model with classification accuracy of 100% was obtained. For the first time in the present study, it was revealed that Shirazi thyme samples have higher antioxidant activity [average IC50 of 37.03 (µg/ml)] compared to different Thymus species [average IC50 of 148.35 (µg/ml)]. FT-IR fingerprint profiles were also used to construct a predictive model for antioxidant activity of the plants based on a reliable PLSR model. The developed PLSR model revealed that IR wavenumbers of 1000–1200, 1700, and 3200–3500 cm?1 are important for antioxidant activity prediction of the analyzed plants. The applied approach has the potential for being used in QC programs not only for fraud mitigation and detection, but also for estimation of antioxidant activity of the culinary plants. 相似文献
93.
In this paper a new and very simple method was developed for the simultaneous determination of binary and ternary mixtures, without prior separation steps. This method is based on the mean centering of ratio spectra. The mathematical explanation of the procedure is illustrated. After modeling procedure, the method has been successfully applied to the simultaneous analysis of binary mixtures of mefnamic acid and paracetamol and ternary mixtures of acetylsalysilic acid, ascorbic acid and paracetamol. The analytical characteristics of the method such as detection limit, accuracy, precision, relative standard deviation (R.S.D.) and relative standard error (R.S.E.) was calculated. The results showed that the proposed method is simple, rapid, accurate and precise method for analysis of binary and ternary mixtures. 相似文献
94.
Hemmateenejad B Akhond M Miri R Shamsipur M 《Journal of chemical information and computer sciences》2003,43(4):1328-1334
95.
A new micelle-mediated extraction method for preconcentration of ultra-trace quantities of beryllium and aluminum as a prior step to their simultaneous spectrophotometric determination has been developed. Chrome Azurol S (CAS), cetyltrimethylammonium bromide (CTAB) and Triton X-114 were used as chelating agent, cationic surfactant for extraction and co-extraction agent, respectively. Mean centering (MC) of ratio spectra has been used for simultaneous analysis of beryllium and aluminum. The optimal extraction and reaction conditions were studied, and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration, and improvement factors) were obtained. Linearity was obeyed in the range of 5-40 ng mL−1 of beryllium and 3-100 ng mL−1 of aluminum. The detection limit of the method is 0.98 and 0.52 ng mL−1 for beryllium and aluminum, respectively. The interference effect of some anions and cations was also tested. The method was applied to the simultaneous determination of beryllium in water samples. 相似文献
96.
Simultaneous determination of phenol and mononitrophenol isomers using PLS regression and conventional and derivative spectrophotometry 总被引:1,自引:0,他引:1
The partial least squares regression method (PLS) was tested as a calibration procedure for the simultaneous determination of phenol, o-nitrophenol, m-nitrophenol and p-nitrophenol by both conventional and first derivative UV/Vis spectrophotometry. The experiments were conducted in the acidic, neutral and basic media. The results obtained by the application of the PLS procedure on the conventional and first derivative spectra in two solvent media were compared. It was found that the results obtained in the basic medium have better performance characteristics than those obtained in the acidic or neutral media. Comparable results were obtained in the case of both conventional and first derivative absorbance data. The proposed method was applied to the determination of the four phenol derivatives in natural spiked water samples at concentration levels between 1.0 and 10.0 microg ml(-1) with average recoveries in the range 96% - 99%. 相似文献
97.
Forouzan Zonouzi Alireza Shayesteh Taher Alizadeh Hamid Dezhampanah Bahram Ghalami-Choobar Afsaneh Zonouzi 《中国化学会会志》2020,67(1):41-45
The (E)-2-hydroxy-5-(aryldiazenyl) benzaldehydes (azo dyes 1–4 ) were synthesized in high purity. As they are insoluble in water, the usual analytical methods cannot be utilized to determine their pKa values. Cyclic voltammetry was experimentally used to determine their pKa values in DMSO solvent. In addition, computational methods and a conductor-like screening model (COSMO) were used to calculate the solvent effect. , , Kexchange, and pKa values were estimated for the azo dyes being studied using the BP86, TPSS, B3LYP, PBE0, TPSSh, and PW6B95 density functionals in def2-TZVP basis sets. The obtained mean absolute deviations (MADs) indicate that the results of BP86, PBE0, and PW6B95 functionals are in good agreement with experimental values. 相似文献
98.
Valiollah Mirkhani Majid Moghadam Shahram Tangestaninejad Bahram Bahramian 《Monatshefte für Chemie / Chemical Monthly》2007,138(12):1303-1308
Summary. The Mn(III)-salen, containing phosphonium groups at the 5,5′-positions of the salen ligand supported on Amberlite IRA-200 via electrostatic binding was used for the oxidation of alkenes and alkanes with sodium periodate at room temperature in the
presence of imidazoles as axial ligands, and the effect of solvent, different axial ligands, and various oxygen donors was
investigated. This heterogenized catalyst shows high catalytic activity in alkene epoxidation and alkane hydroxylation. It
showed high selectivity in the epoxidation of stilbenes, α-pinene, and (R)-(+)-limonene, and exhibits a particular ability to epoxidize linear alkenes. The stability and reusability of this new heterogenized
metallo-salen complex was also investigated. The catalyst was characterized by FTIR, UV-Vis, SEM, and thermal analysis. 相似文献
99.
Bahram Mokhtari 《Supramolecular chemistry》2013,25(12):859-866
This paper introduces a supramolecular-based microextraction technique and examines its ability in preconcentration of tetrahedral oxoanions in the produced water. Diacid p-tert-butylcalix[4]arene in the cone conformation was synthesised and used. The respective parameters including ligand concentration, volume of aqueous disperser, salt effect and extraction time were optimised. The linear range, detection limit (S/N = 3) and precision (relative standard deviation, n = 6) were determined to be in the range of 1.0–280, 2.0–42.0 μg/l and 2.6–11.0%, respectively. 相似文献
100.
Bahram Sadeghi Bigham Marzieh Eskandari Maryam Tahmasbi 《Journal of computational science》2012,3(3):127-131
The polar diagram of a set of points in a plane and its extracted dual EDPD were recently introduced for static and dynamic cases. In this paper, the near-pole polar diagram NPPD for a set of points is presented. This new diagram can be considered as a generalization of the polar diagram and has applications in several communication systems and robotics problems. After reviewing the NPPD of points, we solve the problem for a set of line segments and simple polygons in optimal time Θ(n log n), where n is the number of line segments or polygon vertices. We introduce duality for the NPPD of points and identify some applications. 相似文献