摘要:

AbstractHigh performance liquid chromatography coupled with electrochemical detection (HPLC‐EC) method has been developed for the determination of benzidine and its related congeners in wastewater at the low ng/mL level. With a µ‐Bondapak C18column, 53% acetonitrile (pH 4.7), and electrochemical detection at +1.0 V applied potential, the detection limits range from 3 ng/mL for benzidine to 10 ng/mL for 3,3′‐dichlorobenzidine, assuming a 100 µL injection. The detection limits can be further lowered to the sub‐ng/mL level by incorporating a short precolumn into the HPLC system for on‐line sample enrichment. Recoveries are generally greater than 80% — except for benzidine and 3,3′‐diaminobenzidine which give 50–70% recoveries. Industrial wastewater samples from a coke‐plant and a plant producing 3,3′‐dichlorobenzidine based dyes were successfu

ISSN:0009-4536    

DOI:10.1002/jccs.198800015

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractA sequential extraction technique was used to determine the chemical species of six metals (Fe, Mn, Cu, Zn, Pb, Cd) in suspended matter of the Kaoping and Tsengwen river basins. The samples were taken to cover the fresh and marine characteristics. The precision of the species determination was estimated by the relative difference between the concentration of total metal and the sum concentation of the five species. The accuracy for the measurement of total metal was examined from the recovery of metal spiking. The accuracy of the total determination is better than 94% and the precision of speciation is greater than 90%.Most of the studied metals were found in the Fe‐Mn oxides and residual fractions except that Cd, Zn and Cu have significant amounts in the exchangeable, carbonate, and organic matter phases, respectively. Species other than residual fraction are generally considered as potentially available for biota in aquatic systems, and in most cases, metal pollution could be reflected from the variation of fraction distribution

ISSN:0009-4536    

DOI:10.1002/jccs.198800016

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe quantitative analysis of Cr in super alloys with the presence of a wide variety of elements, Al, B, C, Co, Cu, Hf, Fe, Mn, Mo, Ni, Nb, P, Si, S, Ti, Ta, W, Zr; and trace amounts (a few ppm) of Pb, Se, Bi, Tl and Te has been studied. Persulfate oxidation and diphenylcarbazide photometric method were studied with the purpose of developing a relatively fast and reliable measurement for Cr by wet chemical analysis. The results indicate that the latter is supperior to the former in practical view.In the photometric method, solid sample (0.1g alloys) when treated with HClO4and H2SO4took ca. 72 hrs. for complete dissolution. When treated with HCl followed by HNO3, 0.1 g alloys were completely dissolved within 1&1/2; hours. The best experimental conditions for diphenylcarbazide photometric determination of Cr was thus established. Photometric determination of Cr complexes was made at 540 nm.

ISSN:0009-4536    

DOI:10.1002/jccs.198800017

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe title compound was prepared from the reaction of o‐bisphosphinobenzene with nonacarbonyldiiron. The structure was determined by spectroscopic methods. The mechanism of formation of the complex and its reactivity are discusse

ISSN:0009-4536    

DOI:10.1002/jccs.198800018

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe phase transfer hydrogenation of nitrobenzene to p‐aminophenol has been investigated for the catalysts Pt, Pd, Rh and Ru. The influence of factors such as surfactant concentration, sulfuric acid concentration, hydrogen pressure and temperature on the reaction was determined. It was found that the rate‐determining step for the catalytic hydrogenation of nitrobenzene is the catalytic process by which the hydrogen atom is absorbed on the metal surface. A reaction model is suggested which accounts for the observed hydrogenation selectivity and explains how these factors affect product composition and yield. It is shown that Pt favors p‐aminophenol production, while Pd favors aniline produ

ISSN:0009-4536    

DOI:10.1002/jccs.198800019

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractAluminophosphate molecular sieves, AlPO4− 5 and SAPO−5, were synthesized and characterized by XRD, SEM,29Si and13C NMR, and TGA. Ammonia TPD indicates the moderately acidic nature of SAPO−5 and the non‐acidic nature of AlPO4−5. The activity of the cumene cracking reaction at 350°C for SAPO−5 is similar to that of LaY, while AlPO4−5 and amorphous AlPO4sh

ISSN:0009-4536    

DOI:10.1002/jccs.198800020

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractA series of monodispersed polydimenthylsiloxanes (PDMS) with molecular weights from 3K to 156K were synthesized. The intrinsic viscosity and absolute molecular weight of each monodispersed PDMS was measured and the Mark‐Houwink equation for the PDMS series in toluene at 25°C was derived: [eta;]=2.88 × 10−4M0.613. It was proven that the accurate molecular weight determination of polysiloxanes is not possible using polystyrene (PS) standards. It can be achieved either by using a gel permeation chromatographic method with PDMS standards or by a calculation from the Mark‐Houwink equation using experimental values of intrinsic vi

ISSN:0009-4536    

DOI:10.1002/jccs.198800021

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractSixteen new 8‐siloxyquinolines and 5‐chloro‐8‐siloxyquinolines were synthesized, Structures of all new compounds were determined by IR, NMR, MASS, and elemental analysis. The factors affecting the silylation reactions are disccussed. From the UV absorption pattern, it is shown that the (p→d)π interaction of the Si‐O bon

ISSN:0009-4536    

DOI:10.1002/jccs.198800022

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractA series of phenolic andcis‐dihydrodiol derivatives of 6‐nitrobenzo[a] pyrene and 7‐nitrobenz[a]anthracene were synthesized. The common structural feature of these compounds is that their nitro groups are perpendicular or near perpendicular to the aromatic moieties. From the synthesis of these compounds, it was found that an acetoxy group does not affect the regioselectivity of electrophilic nitration to a polycyclic aromatic hydrocarbon (PAH) and that a nitro substituent can substantially reduce the concerted electrophilic 1,2‐addition of osmium tetroxide to the most olefinic aromatic double bond o

ISSN:0009-4536    

DOI:10.1002/jccs.198800023

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractFive flavonoids, quercetin, quercitrin, hyperin, orientin, and kaempferol, were isolated fromHypericum nagasawaiHayata. The dominant component is quercitrin.

ISSN:0009-4536    

DOI:10.1002/jccs.198800024

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY