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191.
A highly selective sample cleanup procedure combined with molecularly imprinted SPE was developed for the isolation of crystal violet from seawater and seafood samples. The molecularly imprinted polymer was prepared using crystal violet as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross‐linker. The crystal violet‐imprinted polymer was used as the selective sorbent for the SPE of crystal violet. An off‐line molecularly imprinted SPE method followed by HPLC with diode‐array detection for the analysis of crystal violet was also established. Good linearity on the molecularly imprinted SPE columns was obtained from 0 to 200 μg/L (R2 > 0.99). The result demonstrated that the proposed method can be used for the direct determination of crystal violet in seawater and seafood samples. Finally, five samples were analyzed and the following crystal violet concentrations were obtained: 0.92 and 0.52 μg/L in two seawater samples, as well as 0.36 and 0.27 μg/kg in two seafood samples. There is no crystal violet detected in the third seawater sample. 相似文献
192.
Bruno Coulomb Yohan Richardson Christophe Brach-Papa Jean-Luc Boudenne Frédéric Theraulaz 《International journal of environmental analytical chemistry》2013,93(14):1079-1093
A simple and rapid procedure for on-site qualitative and quantitative analysis of organic matter from discharges of municipal wastewater in seawater has been developed. This method is based on the knowledge of the UV signal of both seawater and anthropogenic absorbing matter and on the mathematical deconvolution of the sample spectrum using reference spectra. The main application is the estimation of TOC at the direct outlet of the discharge. This quantitative application is obviously limited by the nature of organic compounds, but the UV estimation allowed us to have an overview of the composition and evolution of organic matter into the polluted area. The application of this procedure has been carried out to study the wastewater dilution into an area receiving urban discharges. Experiments showed satisfactory analytical features with a range of TOC values from 75 to 1500?µM C, and the comparison of the results with those obtained by reference method presented a reasonable correlation (r 2?=?0.9636) in the marine discharge. The results have also allowed us to quickly estimate the plume evolution at the sea surface and in depth. This alternative method could be integrated in a portable device for on-site analysis and multiplication of measurements for relevant results, or in a continuous flow analyser. 相似文献
193.
This paper describes a robust, sensitive method for measurement of low silicate in natural water. The method is based on the reaction of silicate with ammonium molybdate to form a yellow silicomolybdate complex, which is then reduced to silicomolybdenum blue by ascorbic acid. This method shows no refractive index effect and a small salinity effect that can be corrected for seawater samples. It was found that the use of poly-vinyl alcohol can prevent the precipitation formation in the ammonium molybdate solution and improve the stability of the silicomolybdenum blue complex. The sensitivity of this method is substantially enhanced by using a liquid-waveguide capillary cell. The detection limit is 0.1 μM, and working range is 0.1-10 μM for using 2-m liquid-waveguide capillary cell (LWCC). The method can be used for both freshwater and seawater samples and has been used to study the distribution of silicate in surface seawater of Gulf Stream in Florida straight. 相似文献
194.
The design of various multistage RO systems under different feed concentration and product specification is presented in this work. An optimization method using the process synthesis approach to design an RO system has been developed. First, a simplified superstructure that contains all the feasible design in present desalination process has been presented. It offers extensive flexibility towards optimizing various types of RO system and thus may be used for the selection of the optimal structural and operating schemes. A pressure vessel model that takes into account the pressure drop and concentration changes in the membrane channel has also been given to simulate multi-element performance in the pressure vessel. Then the cost equation relating the capital and operating cost to the design variables, as well as the structural variables of the designed system have been introduced in the objective function. Finally the optimum design problem can be formulated as a mixed-integer nonlinear programming (MINLP) problem, which minimizes the total annualized cost. The solution to the problem includes optimal arrangement of the RO modules, pumps, energy recovery devices, the optimal operating conditions, and the optimal selection of types and number of membrane elements. The effectiveness of this design methodology has been demonstrated by solving several seawater desalination cases. Some of the trends of the optimum RO system design have been presented. 相似文献
195.
Otto Vogl 《Journal of polymer science. Part A, Polymer chemistry》2004,42(3):795-818
This article describes the scientific investigations and accomplishments in the life of the author. After a dissertation on steroids, several years were spent on alkaloids and research on heterocyclic compounds. Much of the author's career was devoted to research on aldehyde polymerization, the discovery of the polymerization of higher aldehydes and their isotactic polymers, and haloaldehyde polymerization. The latter led to our work on the ceiling temperature of polymerization, on new polymerization techniques [involving the ceiling temperature and the concept of macromolecular asymmetry (polymer helicity)], and the genesis of chloral polymerization. Another important period was devoted to functional polymers, polymeric stabilizers, and polymeric drugs. Other research activities included studies of unusual polymers, head-to-head polymers, spacer groups in polymers, and oriental lacquers. Attention was also paid to the use of novel and unusual polymer intermediates, polymerization under extreme conditions and the preparation and behavior of uncommon polymer structures. Finally, it was recognized that macromolecules can be categorized with increasing frequency as polymers with broad and narrow molecular weight distributions and uniform polymers. The ultimate unity is isotopically pure uniform polymers, single macromolecular species. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 795–818, 2004 相似文献
196.
197.
A method for the determination of ultratrace amounts of Cr, Fe, Mn, Pb and Zn in seawater has been developed. It combined the low-blank magnesium hydroxide coprecipitation procedure with quadrupole inductively coupled plasma mass spectrometry and used the dynamic reaction cell technique to resolve the polyatomic interferences arising from the residual matrix, the solvent and plasma gases. Detection limits (3σB, n = 10) for Cr, Fe, Mn, Pb and Zn were 0.02, 0.10, 0.01, 0.002 and 0.19 nM, respectively, using 50 mL of seawater sample. The accuracy of the analytical procedure was verified by the analysis of the seawater reference materials CASS-4, NASS-5, SAFe D2 and SAFe S. The analytical precision ranged from 3% to 16% (n = 6), with a sample throughput of about 6 samples h−1. 相似文献
198.
199.
This article describes an analytical method for the separation, preconcentration and determination of 232Th in seawater samples at sub-ng/L levels using a NOBIAS CHELATE PA1 resin and a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). The resin showed excellent adsorption of 232Th at a low pH of 2.4 ± 0.4 in a relatively small volume (200 mL) of seawater. 232Th adsorbed on the resin was easily eluted using 5 mL of 0.8 M HNO3. An enrichment factor of 40 was achieved for 232Th analysis. Ethylenediamine-tetraacetic acid disodium salt dehydrate (EDTA) was used to investigate the effect of 232Th-binding organic ligand on the retention of 232Th on the chelating resin. Results obtained using acidified samples (pH of 2.4 ± 0.4) showed EDTA had no significant effect on 232Th recovery, indicating that at this low pH, 232Th was dissociated from the 232Th-binding organic ligand and quantitatively retained on the NOBIAS CHELATE PA1 resin. The developed analytical method was characterized by a separation and preconcentration taking approximately 4 h and a low detection limit of 0.0038 ng/L for 232Th, and was successfully applied to the determination of 232Th in seawater samples collected from coastal areas, Japan. 相似文献
200.
Solid-phase extraction (SPE) combined with liquid chromatography electrospray mass spectrometry (LC-(ESI)MS) was used to determine 16 non-ionic and anionic surfactants in different environmental water samples at ng L−1 levels. The proposed method is sensitive and simple and has good linear range and detection limits (less than 50 ng L−1) for most compound classes.The effect of ion suppression was studied in aqueous matrices from several treatment plants—including urban and industrial wastewater treatment plants (WWTPs), drinking-water treatment plants (DWTPs) and seawater desalination plants (SWDPs)—and it was considered when quantifying our samples. In addition, conventional treatments and tertiary treatments that use advanced membrane technologies, such as ultrafiltration (UF) and reverse osmosis (RO) were evaluated in order to determine their efficiency in eliminating these compounds.The concentrations of non-ionic surfactants in the raw waters studied ranged from 0.2 to 100 μg L−1. In effluents, the concentrations ranged from 0.1 to 5 μg L−1, which reflects consistent elimination. Anionic surfactants were present in all waters studied at higher levels. Levels up to 3900 μg L−1 of linear alkylbenzene sulfonates (LASs) and 32,000 μg L−1 of alkyl ethoxysulfates (AESs) were detected in urban WWTP influents, while levels up to 25 μg L−1 of LASs and 114 μg L−1 of AESs were found in drinking-water and desalination treatment plants.The results indicate that conventional processes alone are not sufficient to completely remove the studied surfactants from waste streams. Tertiary treatments that use advanced membrane technologies such as UF and RO can further reduce the amount of target compounds in the effluent water. 相似文献