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51.
A new liquid chromatographic (LC)-chemometric approach was developed for the determination of sunset yellow (SUN) and tartrazine (TAR) in commercial preparations. This approach uses LC and chemometric calibration methods, i.e., classical least-squares (CLS), principal component regression (PCR), and partial-least squares (PLS), simultaneously. The combined LC-chemometric approaches, denoted as LC-CLS, LC-PCR, and LC-PLS, are based on photodiode array (PDA) detection at multiple wavelengths. Optimum chromatographic separation of SUN and TAR with allura red as the internal standard (IS) was obtained by using a Waters Symmetry C18 column, 5 microm, 4.6 x 250 mm, and 0.2 M acetate buffer (pH 5)-acetonitrile-methano-bidistilled water (55 + 20 + 15 + 10, v/v) as the mobile phase at a flow rate of 1.9 mL/min. The LC data sets consisting of the ratios of analyte peak areas to the IS peak area were obtained by using PDA detection at 5 wavelengths (465, 470, 475, 480, and 485 nm). LC-chemometric calibrations for SUN and TAR were separately constructed by using the relationship between the peak-area ratio and the training sets for each colorant. LC-chemometric approaches were tested for different synthetic mixtures containing SUN and TAR in the presence of the IS. These LC-chemometric calibrations were applied to a commercial preparation of the 2 colorants. The experimental results of the LC-chemometric approaches were compared with those obtained by a developed classical LC method using single-wavelength detection. 相似文献
52.
新试剂N-苯基-N′-(氨基对苯磺酸钠)硫脲的合成及其在微量金(Ⅲ)测定中的应用 总被引:8,自引:0,他引:8
介绍了新试剂N 苯基 N′ (氨基对苯磺酸钠 )硫脲 (PPT)的合成方法。并研究了与金的显色条件 ,建立了光度法测定微量金的新方法。在pH 5 .0~ 5 8的HAc NaAc缓冲体系中 ,在溴化十六烷基三甲胺 (CTMAB)存在下 ,Au(Ⅲ )与PPT形成组成比 1∶3的黄色水溶性络合物 ,其最大吸收峰位于 31 7.0nm ,表观摩尔吸光系数ε=3.68× 1 0 4 L/mol·cm ,Au(Ⅲ )含量在 0~ 80 μg/2 5mL范围内服从比尔定律。 相似文献
53.
M. Yakup Arca Meltem Ylmaz Emine Yaln Gülay Bayramo
lu 《Journal of membrane science》2004,240(1-2):167-178
Poly(hydroxyethyl methacrylate), pHEMA, and a composite pHEMA/chitosan networks were synthesized in the membrane form via UV initiated photo-polymerisation in the presence of an initiator ,′-azoisobutyronitrile. Reactive Yellow 2 (RY-2) was covalently immobilised as a dye–ligand onto both membranes. The polarity and surface energy of the investigated membranes were determined by contact angle measurement. The incorporation of chitosan in the pHEMA networks produced more hydrophilic surface, as indicated by contact angle analysis. The binding characteristics of lysozyme, γ-globulins, human serum albumin (HSA) and bovine serum albumin (BSA) to pHEMA-RY-2 and pHEMA/chitosan-RY-2 affinity membranes have been investigated from aqueous solution and their dye–ligand free forms were used as control systems. When chitosan was incorporated in the pHEMA network as a cationic polymer led to higher adsorption capacity for the lysozyme. Selective adsorption behaviour was also observed in the case of pHEMA/chitosan-RY-2 membrane for the lysozyme. The non-specific adsorptions of the lysozyme on the pHEMA and pHEMA/chitosan membranes were about 1.9 and 7.2 mg/ml, respectively. These were negligible for all others investigated proteins. The lysozyme adsorption data was analysed using the first-order and the second-order models. The first-order equation in both affinity membrane systems is the most appropriate equation to predict the adsorption capacities of the adsorbents. The adsorption isotherms well fitted the combined Langmuir–Freundlich model. A theoretical analysis has been conducted to estimate the thermodynamic contributions (changes in enthalpy, entropy and Gibbs free energy) for the adsorption of lysozyme to both dye–ligand immobilised membranes. The adsorption capacities of both dye–ligand immobilised membranes increased with increasing the temperature while decreased with increasing the NaCl concentration. Both affinity membranes are stable when subjected to sanitization with sodium hydroxide after repeated separation–elution cycles. 相似文献
54.
A new melamine based polymeric sequestering resin was prepared for preconcentration and separation of hexavalent chromium from water, and its sequestering action was investigated. The water-insoluble, cross-linked sequestering resin was formed by reaction with bromosuccinic acid and cross-linking of melamine. The active sequestering group on the resin is NH-(Succinic acid) or salt thereof. The resulting chelating resin was characterized by infrared spectra. The newly prepared resin quantitatively retained Cr(VI) at pH 2.0-4.0 when the flow rate was maintained between 1 and 5 ml min−1. The retained Cr(VI) was instantaneously eluted with 25 ml of 0.1 M NaOH. The chromium species were determined by a flame atomic absorption spectrometer. The limits of detection for Cr(VI) and Cr(III) were found to be 5.3 and 4.2 μg l−1, respectively. The precision and accuracy of the proposed procedure was checked by the use synthetic and reference steel samples. The established preconcentration method was successfully applied to the determination and selective separation of Cr(VI) in electroplating industry wastewater. Total concentrations determined by the spectrophotometric method (110.3±0.6 g l−1 Cr(VI) and 1.2±0.3 g l−1 Cr(III)) are compared with those found by FAAS and the obtained results (110.4±1.8 g l−1 Cr(VI) and 1.4±0.5 g l−1 Cr(III)) show good agreement. 相似文献
55.
A new (E,E)-dioxime, (6Z,7Z)-15,16-dihydro-14H-dibenzo[b,h][1,10,4, 7]dithiadiazacyclotride-cine-6,7(5H,8H)-dionedioxime (H
2
L) has been synthesized by reacting cyanogen-di-N-oxide (2) with 2,2′-[propane-1,3-diylbis(thio)]dianiline (1). Mononuclear complexes (4) and (5) of this ligand have been synthesized by reacting the vic-dioxime (H2L) with NiCl2 · 6H2O and CoCl2 · 6H2O, respectively. The BF
2
+
capped Ni(II) and Co(III) complexes (6) and (7) of the dioxime have been synthesized from (4) and (5). The new compounds were characterized by a combination of elemental analysis, 1H- and 13C-n.m.r, i.r. and m.s. spectral data. 相似文献
56.
Luminita Cianga Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2002,40(8):995-1004
Two types of novel functionalized N‐[4‐(4′‐hydroxyphenyloxycarbonyl)phenyl]maleimide and N‐(4‐{[2‐(3‐thienyl)acetyl]oxyphenyl}oxycarbonylphenyl)maleimide (MIThi) were synthesized starting from 4‐maleimido benzoic acid. Photoinduced radical homopolymerization of MIThi and its copolymerization with styrene were performed at room temperature to give linear polymers containing pendant thienyl moieties using ω,ω‐dimethoxy‐ω‐phenylacetophenone as an initiator. Copolymers' compositions and the equilibrium constant (K) for electron donor–acceptor complex formation suggest an alternating nature of the copolymerization. The monomer reactivity ratios and Alfrey–Price Q,e values were also determined. The thermal behavior of the new synthesized monomers and polymers was investigated by differential scanning calorimetry and thermogravimetric analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 995–1004, 2002 相似文献
57.
N. K. Tunali H. N. Erten S. Kinikoğlu Ş. Gümüş 《Journal of Radioanalytical and Nuclear Chemistry》1979,49(2):225-237
The extraction of iodine and bromine under various conditions from their saturated aqueous solutions by CCl4, C6H6 and o-xylene has been studied. The data obtained from the experiments carried out at various temperatures, for H2O(I2)−CCl4 and H2O(I2)−C6H6 systems, exhibit an Arrhenius behaviour. The overall activation energy calculated for the extraction in the H2O(I2)−CCl4 system, 650±50 cal·mol−1 is lower than that of H2O(I2)−C6H6, 3600±300 cal·mol−1. The use of the solubility parameter for the interpretation of the data in the extraction of iodine is investigated. The
data obtained in multiple extractions are treated by using the analogy between extraction and radioactive decay. The half
number of extraction for each system is determined. The complex curves obtained in the H2O(I2)−CCl4 and H2O(I2) −Br2)−CCl4 systems are resolved into two components. 相似文献
58.
M.Tahir Güllüo?lu?enay Yurdakul 《Journal of Molecular Structure》2002,641(1):93-100
New Hofmann-type complexes and clathrates of the forms M(piperidine)2Ni(CN)4 and M(piperidine)2Ni(CN)4·1.5G (M=Cd, Co, Ni or Cu; G=benzene) were prepared in powder form and their infrared and Raman spectra are reported. The spectral features suggest that these compounds are similar in structure to the Hofmann-type clathrates except for the copper compounds. The complex and clathrate of Cu have different spectral features in comparison with its analogues due to the Jahn-Teller effect. 相似文献
59.
60.
Two new reagents for in situ peptide coupling based on the 2-mercaptopyrimidine core have been developed. The readily prepared thiouronium salts were found to promote both peptide and segment coupling efficiently with low racemization/epimerization levels. 相似文献