Simultaneous determination of cloramphenicol, salicylic acid and resorcinol by capillary zone electrophoresis and its application to pharmaceutical dosage forms

This study demonstrates the separation of active ingredients in acne formulations (salicylic acid, cloramphenicol and resorcinol in presence of azulene) by capillary zone electrophoresis. Factors affecting their separations were the buffer pH and concentration, applied voltage, sample preparation, and presence of additives. Optimun results were obtained with a 50 mM sodium tetraborate-50 mM sodium phosphate, pH 9.0. The carrier electrolyte gave baseline separation with good resolution, short migration times (<6 min), great reproducibility and accuracy. Calibration plots were linear over at least three orders of magnitude of analyte concentrations, the lower limits of detection being within the range 0.39-1.25 μg ml⁻¹. The procedure was fast and reliable and commercial pharmaceuticals could be analysed without prior sample clean-up procedure.     

Tertiary amine-mediated synthesis of microporous carbon membranes

Microporous carbon membranes were prepared on an -alumina support by a pyrolysis of cationic tertiary amine/anionic polymer composites. The precursor solutions contain a thermosetting resorcinol/formaldehyde (RF) polymer and a cationic tertiary amine. Three types of cationic tertiary amines with different chain lengths were used, such as tetramethlammonium bromide (TMAB), tetrapropylammonium bromide (TPAB) and cetyltrimethylammonium bromide (CTAB). A porous structure was produced by a decomposition of the amine and the resulting pores assisted the further gasification of the RF polymer at high temperature. The carbon/alumina membranes have thin and continuous carbon top layers with a thickness of 1 μm. Gas permeation tests were performed using single gases of CO₂, O₂, N₂, CF₄, n-C₄H₁₀ and i-C₄H₁₀, as well as binary mixtures of CH₄/n-C₄H₁₀ and N₂/CF₄ at different temperatures between 23 and 150 °C. The carbon membrane prepared using TMAB showed separation factors higher than 650 for the CH₄/n-C₄H₁₀ mixtures and higher than 8100 for the N₂/CF₄ mixture. From the permeation of pure gases with different molecular sizes, the pore sizes of the carbon membrane prepared using TMAB, TPAB and CTAB are estimated to be 4.0, 5.0 and larger than 5.5 Å, respectively, indicating that the micropore size of the carbon membranes is controllable by using different amines.     

Aminopyrene functionalized mesoporous silica for the selective determination of resorcinol

Aminopyrene was convalently anchored onto the surface of mesoporous MCM-41 silica by post-grafting. This organic-inorganic hybrid has been applied as sensing material to phenols determination. Experimental results reveal that the functionalized material presents good sensitivity and selectivity towards resorcinol and can be used for resorcinol determination in water at pH 6.0. The fluorescence intensity of aminopyrene functionalized mesoporous silica decreases proportionally to the logarithm of resorcinol concentration in water. The linear range for resorcinol detection lies in 4.79-163 μM with a detection limit of 2.86 μM (S/N = 3).     

Voltammetric Study and Rapid Quantification of Resorcinol in Hair Dye and Biological Samples Using Ultrasensitive Maghemite/MWCNT Modified Carbon Paste Electrode

Increased concern over the risk resorcinol (RS) pose to ecology and humans, led to its position in European Union Category 1 list of endocrine disruptors. Legal measures restricted RS utilization and hence crucial to monitor its levels in the environment. Herein we report development of highly efficient and economically viable electrochemical sensor for quantitative determination of RS based on 77Maghemite/MultiWall Carbon Nanotube (M/MWCNT) modified carbon paste electrode. M/MWCNT was synthesized via strategic IR irradiation for the first time, a promising approach to overcome other complicated chemical routes. Powder X‐ray diffraction (PXRD), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM) and Energy dispersive X‐ray (EDX) were used for characterization. Using Differential Pulse Voltammetry (DPV), we report the lowest detection limit at 0.02 μM. The potential application of the sensor was accomplished as a result of excellent recoveries made from real samples fortified with RS. Results indicated the proficiency of the sensor reliable for rapid, onsite monitoring of RS water contamination and in biological matrices.     

Preparation,characterization and applications of polyurethane foam functionalized with resorcinol for quantitative separation and determination of silver(I) and mercury(II) from tap and wastewater

A stable chelating resin matrix was prepared by covalently linking resorcinol with polyurethane foam matrix through a –N=N– group. Preconcentration and determination of trace Ag⁺ and Hg²⁺ ions from samples of different origin, using Res-PUF, were studied. Various conditions influencing the sorption of these metal ions onto Res-PUF were optimized. The kinetics of sorption of the Ag⁺ and Hg²⁺ by Res-PUF were found to be fast, reached equilibrium in few minutes (5–10?min) and followed a first-order rate equation with an overall rate constant k in 0.102 and 0.267/min, respectively. Study of the variation of the sorption of the tested metal ions with temperature yielded average values for ΔG, ΔH and ΔS of ?3.94, ?22.02 and ?58.37, respectively. The mean free sorption energy (E) computed from the Dubinin–Radushkevich (D–R) isotherm was found to be equal to 8.91 kJ/mol, which reflects the chelation sorption process. The capacities of the foam material were 0.15 and 0.07?mmol/g for Ag⁺ and Hg²⁺, respectively. Preconcentration factors of?>?50 were achieved (RSD?≈?5.99). The proposed preconcentration procedure was applied successfully to the determination of trace metal ions in natural and wastewater samples.     

Synthesis of novel benzopyrano[3,2-c]coumarins via tandem base promoted nucleophilic substitution and intramolecular electrophilic aromatic cyclization

Efficient and facile synthesis of 7H-benzopyrano[3,2-c]coumarins has been achieved by mild base promoted reaction of 4-chloro-3-formylcoumarin with diversely functionalized resorcinols. All the products were obtained as pure precipitates from the reaction mixture and the structure of the product was confirmed by X-ray analysis.     

纳米银增敏化学发光体系测定间苯二酚

采用柠檬酸钠包覆化学还原法制备纳米银粒子,将该纳米银粒子加入到碱性鲁米诺-铁氰化钾化学发光体系,体系的化学发光强度明显增强,而间苯二酚的加入能抑制该体系的化学发光,据此建立了流动注射化学发光法定量分析痕量间苯二酚的新方法.考察了鲁米诺、铁氰化钾、氢氧化钠以及纳米银浓度对化学发光体系的影响.在优化的实验条件下,该方法测定...     

Resorcinarenes的合成及其边缘化学修饰(Ⅱ)

探讨了烷基醛类（丁醛、戊醛、异丁醛）的Ｒｅｓｏｒｃｉｎａｒｅｎｅｓ的合成及其边缘化学修饰（乙酰化、甲基化），研究了烷基取代基对合成的影响，并用ＩＲ，＾１ＨＮＭＲ，ＭＳ和ＵＶ对这些化合物进行了表征。     

Photostabilizing of bisphenol A polycarbonate by using UV-absorbers and self protective block copolymers based on resorcinol polyarylate blocks

Bisphenol A polycarbonate degrades due to sunlight, humidity and oxygen. In this study two possible techniques to stabilize the polymer were compared, i.e. blending of UV-absorbers (UVAs) into the polymer or using block copolymers based on resorcinol polyarylates. Combination of different analysis techniques shows that the protection by UVAs is not as good as by the resorcinol polyarylate block copolymers. The block copolymer rearranges itself through a photo-Fries rearrangement within hours into a UV-absorbing top layer. Two different block compositions were studied, and the copolymer with the highest concentration of resorcinol polyarylate groups shows the best protection.     

Iridium-catalyzed C-H activation/borylation/oxidation for the preparation of bis-protected phloroglucinol derivatives

The preparation of bis-protected phloroglucinol derivatives from a range of protected resorcinol substrates is presented. Functionalization was achieved via a two-step, one-pot iridium-catalyzed C-H activation/borylation/oxidation protocol. Our system gave high conversions to the arylboronic esters and good yields of the desired phenols following subsequent oxidation. A range of common protecting group categories was studied including alkyl, silyl, ether and ester.