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1.
陈声培  黄国贤 《电化学》1999,5(3):252-260
采用原位红反射光谱(in-situ-FTIRS)结合紫外可见光谱(UV/Vis)和电化学徨伏安技术(CV),研究了「Os^Ⅵ(N)(NH3)4」(CF3SO3)3的电化学诱导桥氮偶联过程。首次在Pt电极上检测到桥氮混合价锇物中「Os-N≡N-oS」及其随电位的变化过程。在约2m mol/L「Os^Ⅵ(N)(NH)」(CF要的乙腈溶液中,选取0.4--1.0V电位区间100mV/s扫描速度,对Pt或  相似文献   

2.
采用Phoenix8000总有机碳分析仪,以UV-Na2S2O8-NDIR氧化波了水中痕量机碳(TOC)。讨论了酸度、氧化剂浓度、有机物氧化效果、无机碳对测定结果的影响等。方法检出限为0.0024mg/L,回收率为94.0% ̄112%,精密度0.8 ̄5.3%。该法已应用于湖水、河水、自来水、地下水、泉水等自然水体及纯净水、蒸馏水、反渗透(RO)净化水特瓣总有机碳含量的测定。  相似文献   

3.
魏俊发  俞贤达 《分子催化》1998,12(4):271-278
设计合成了5种新型双核铜配合物,用EA,IR,UV-Vis,XPS,EPR等进行了结构表征,并研究了这些Cu2配合物模拟双核铜单加氧酶多巴胺β-羟化酶催化苯乙烯环氧化反应的特征。结果表明,这些配合物具有两种类型的结构:脱质子型Cu2LOH和非脱质子型「(Cu2H2LX)Y」Y(X=Y=Cl^1-,Br^-;X=OH,Y=O2ClO^-2),两类配合物可相互转化。非脱质子型配合物催化PhIO对苯乙烯  相似文献   

4.
刘希东 《分析化学》2002,30(1):50-52
在稀磷酸介质中,二氧化氯(ClO2)氧化I离子形成 I3配阴离子,I3进一步与结晶紫(CV)阳离子形成离子缔合物[CV][I3」。在聚乙烯醇存在下,该离子缔合物最大吸收波长λmax位于552 nm处,摩尔吸光系数ε=25 × 105L·mol-1·cm-1,对 ClO2的检出限为 0.6 μg/L,线性范围是 0.6~280μg/L。加入适量 KF溶液可消除自来水中Fe(Ⅲ)的干扰。方法对μg/L级ClO2 的测定有较好的选择性,可成功地用于自来水样品分析。  相似文献   

5.
研究了合成聚(2,4-二甲氧基对苯乙炔)的有机可溶性前聚物的反应条件与单体转化率和前聚物产率的关系。实验结果表明:NaOH是聚合反应的有效引发剂,适宜的反应条件为:单体与NaOH摩尔比为1:1,单体浓度0.05-0.2mol/L,聚合时间2h,温度低5℃,正己烷、石油醚作为有机提取剂可有效提高前聚物产率。用IR、UV-Vis'^HNMR,TGA和 DSC对前聚物进行了表征。  相似文献   

6.
CO2和CH3OH直接合成碳酸二甲酯Cu-Ni/V2O5-SiO2催化剂   总被引:11,自引:0,他引:11  
采用表面反应改性法制备了V2O5-SiO2(VSiO)表面复合物,用等体积浸渍法制备了VSiO担载的Cu-Ni双金属催化剂,用IR,TPD,TPSR和微反技术研究了CO2和CH3OH在催化剂表面上的化学吸附与反应性能。结果表明,在Cu-Ni/VSiO催化剂上存在着金属位Cu-Ni合金,Lewis酸位V^n+和Lewis碱位V=O三类活性中心;CO2在金属位和Lewis酸位协同作用下可生成CO2卧式  相似文献   

7.
脱氧核糖核酸变性和损伤的吸附伏安法研究   总被引:2,自引:0,他引:2  
陆宗鹏  卢莠芬 《分析化学》1996,24(4):463-466
本文用汞电极(HMDE)二次导数阴极吸附伏安(SD-AdCSV)和碳电极(GCE、CPE)导数循环伏安(FD-CV)法研究了核酸受热、紫外线、超声波和丝裂霉素C(MMC)作用下的变性作用。在0.1mol/L(K2HPO4+KH2PO4)-0.1mol.L NaCl(pH7.0)底液中,吸附的单股(ss-)和双螺旋(ds-)DNA分别在HMDE上得到特征还原峰P3和P2,和在碳电极上得到氧化峰A。物  相似文献   

8.
采用原位 红外反射 光谱(in_situ F T I R S) 结合紫 外可见 光谱( U V/ Vis) 和 电化学循 环伏安技术( C V) ,研究了[ Os V I( N)( N H3) 4]( C F3 S O3) 3 的 电化 学诱 导桥 氮偶 联过 程. 首次 在 Pt 电 极上检测到桥 氮 混 合 价 锇 物 种[ Os_ N ≡ N_ Os] 及 其 随 电 位 的 变 化 过 程 . 在 约 2 m m ol/ L 〔 Os V I( N)( N H3) 4〕( C F3 S O3) 3 + 0 .1 m ol/ L T B A H 的乙腈溶 液中,选 取0 .4 ~- 1 .0 V 电位 区间 100 m V/s 扫描速度 ,对 Pt 或 G C 电 极进行电 化学循环 伏安处 理,处 理 后的 电极 表 面均 可积 累 一层 深绿 色 的沉积物,表 明电化 学诱导 N_ N 偶联效 应已在 电极上 发生, 并形 成了 混合 价 桥氮 络合 物. 同时 ,在 上述过程中 所生成 的混合价 锇氮物种 ,有可能 较强地 吸附在电 极表 面,且 形成 一定 厚度 的表 面层, 从而减缓了 体系中 Os V I≡ N 物种在电 极上的 继续还 原.同 时可 以看 到,随 着 C V 的 不 断进 行,溶 液 颜色将逐渐 地由黄变 绿.经过 长时间( 约  相似文献   

9.
研究了N-乙烯基咔唑-丙烯酸共聚物(NVC-AA)和微量的钼簇合物「Mo3O2(O2CCH3)6(H2O)3」Br2.2H2O在水溶液相互作用及其溶液荧光。实验发现,体系中存在单体荧光(375nm)和二聚体激态缔合物荧光(500nm)。荧光强度分别随钼簇合物的浓度啬和pH值的提高而增强。  相似文献   

10.
维脑路通与铜(Ⅱ)的配位化学研究   总被引:4,自引:0,他引:4  
用单扫描极谱法研究了Cu^2+与维脑路通(VENORUTON,简称VRT)形成配合物的条件和机理,在磷酸盐缓冲溶液中(PH7.0),Cu^2+与维脑路通配位并产生1个不可逆还原波,其峰电位为-0.55V(vs.SCE)。配合物的摩尔组成比为Cu^2+,VRT=1:2,表观稳定常数为1.1*10^11。  相似文献   

11.
北京地区臭氧污染的来源分析   总被引:32,自引:1,他引:31  
光化学烟雾污染是影响北京地区夏季空气质量的一个重要环境问题.利用区域空气质量模(CAMx)对2000年6月底至7月初发生在北京地区的臭氧污染过程进行模拟,运用臭氧源识别技术(OSAT)和地区臭氧评估技术(GOAT),量化了不同地区的污染源排放对北京市城近郊区臭氧污染的贡献,探讨了周边地区排放的臭氧贡献方式问题,分析了北京地区臭氧污染的化学机制特征.研究表明,北京地区臭氧污染分布存在显著差异,并且具有明显的区域性特征,定陵地区的超标臭氧主要受到城近郊区烟羽的严重影响(占55%),城近郊区则除了受到北京市的前体物排放影响外(占46%),来自天津市、河北省南部地区的贡献往往也占有重要份额;周边地区对北京市城近郊区的贡献中,直接输入的臭氧约占七层,其余部分以输入前体物的方式贡献臭氧;北京城近郊区的臭氧生成主要受挥发性有机物控制,而在远郊区县和农村地区臭氧生成对氮氧化物变得更为敏感.对北京地区臭氧污染的源排放控制,需要综合考虑各种臭氧来源和不同贡献方式的重要性,以及臭氧生成机制的变化规律.  相似文献   

12.
Barcelona's tap water is supplied by the Llobregat and Ter rivers, which have significant differences in raw water quality. Volatile organic compounds (VOCs) from Barcelona tap water were isolated by closed-loop stripping analysis (CLSA) and identified and determined by gas chromatography-mass spectrometry. The results showed that the Ter river gives the better quality tap water. VOCs, in particular solvents, phosphates, hydrocarbons, C3 and C4 alkylbenzenes and surfactant-related compounds such as C10-C13 alkylbenzenes and non-ionic compounds such as polyethoxylated nonylphenols and their brominated derivatives are present at the ppb level. The last two types of compounds have not previously been reported using the CLSA technique.  相似文献   

13.
建立了同时测定饮用水源水中24种挥发性有机物(VOCs)的顶空固相微萃取-气相色谱-质谱法.用75 μm CarboxenTM-Polydimethylsiloxane(CAR-PDMS)固相微萃取柱顶空萃取水样中的VOCs,VOCs用气相色谱-质谱联用仪检测,采用内标法定量.对萃取柱涂层、样品盐度、萃取温度和萃取时间等样品前处理条件进行了优化,VOCs的检出限在0.03~0.31 μg/L之间,线性相关系数r>0.996(二氯甲烷和三氯甲烷除外).对饮用水源水实际水样0.50μg/L和1.00 μg/L两个加标浓度水平的回收率进行了测定,三氯甲烷回收率均值分别为104%和142%,其余VOCs回收率分别为90.0%~120%和88.0%~110%,除二氯甲烷和三氯甲烷外,其余VOCs测定结果的相对标准偏差均小于15.0%(n=6).该方法适用于饮用水源水中挥发性有机物的监测分析.  相似文献   

14.
Deterioration of water quality has become an ecological threat in many industrial areas worldwide due to unmanaged anthropogenic activities. Contaminants therein find out their ways to drinking water-pipes via broken or leak old- pipes. The current study aims at evaluating the suitability of tap water, collected from the main-ten-industrial cities of Egypt, for drinking purposes. Shallow and deep ground waters were also sampled from the same locations. This is one of the few research projects that are interested in quantifying the acrylamide in drinking water. The obtained results indicate that concentrations of COD, BOD, Fe, Mn, Ni, Pb, Cd, Zn and Hg were within the permissible levels in tap water while surpassed these levels in both shallow and deep ground waters. Acrylamide levels did not exceed the acceptable levels in all water samples (drinking, surface and deep ground waters). Overall, no potential risks were associated with the oral ingestion of tap water in all studied locations for both adults and children (all hazard quotient (HQ) values, defined as exposure intake dose of contaminants relative to the maximum permissible daily intake dose were below “1″). However, inorganic pollutants that exist in ground waters may cause undesirable dermal impacts when used for irrigating the green areas in these cities (used for picnics and as playgrounds). In this context, most HQ values associated with ground water dermal contact were above “1”. Specifically, Mn, Ni, Pb and Cd hazards exist for children (HQ > 1) while Ni, Pb and Cd toxicity detected for adults. This result; therefore, highlights the indirect negative impacts of industrialization on human health.  相似文献   

15.
Solid-phase microextraction (SPME) has been applied to the quantitative analysis of 60 volatile organic compounds (VOCs) in drinking water. Equilibration curves for the partitioning of the VOCs between the fiber coating and fortified water obtained at 20, 50, and 80 °C are found between the theoretical curves for completely agitated and non-agitated samples. Two important factors for the amount adsorbed by the SPME fiber coating are the extraction time and the fiber coating/water distribution coefficient, KFW . Both depend on the sample temperature, but in a counteracting manner: Increasing the temperature shortened the equilibration times, especially for the heavier VOCs, but also lead to lower KFW values, and consequently a lower sensitivity of the method. KFW values are determined for 33 of the VOCs at 40, 60, and 80°C and the heats of adsorption,–ΔH, are calculated. The nature of the adsorption is found to be exothermic which explains the decreasing sensitivity of the method with increasing temperature. Detection limits were typically from 20 ng/l to 200 ng/l, except for the very light VOCs with which detection difficulties were encountered. For all of the VOCs the linear range extended from the lowest concentration at which they were actually detected to at least 5 mg/l. The precision, 3% average standard deviation when an internal standard was used, was satisfactory for most quantitative routine analysis. SPME was also applied to head-space (HS) analysis of drinking water through the coupled equilibrium between water/head-space/fiber coating. HS-SPME is demonstrated to have shorter equilibration times than SPME directly from the water and equal sensitivities, except for the very light VOCs. Water samples from a drinking water plant contaminated in the low μg/l range with 1,1,1-trichloroethane, trichloroethene and tetrachloroethene were analyzed. There seems to be a reasonable agreement between results obtained by SPME and purge & trap. It is concluded that SPME has a great potential for drinking water analysis.  相似文献   

16.
Beijing,the capital of China,frequently suffers from the high levels of ozone in summer.A 3-D regional chemical transport model,the Comprehensive Air Quality Model with extensions(CAMx),has been used to simulate a heavy O3 pollution episode in Beijing during June 26―July 2,2000.Ozone Source Apportionment Technology(OSAT) and Geographic Ozone Assessment Technology(GOAT) were applied to quantify the contributions of the precursor emissions from different regions to O3 concentrations in Beijing,to identify the...  相似文献   

17.
In this work, three typical phenol endocrine-disrupting compounds (EDCs), namely Bisphenol A (BPA), 4-nonylphenol (4-NP) and 4-tert-octyphenol (4-t-OP), were detected in water samples from the whole drinking water supply chain of seven water plants at three hydrographic periods in Suzhou, China. Almost all of the drinking water in urban area of Suzhou city is provided by the seven water plants. Every link of drinking water supply, including raw water, finished water and tap water were monitored. The results indicated that BPA and 4-NP were detected in all samples with the concentration of 0.067–0.118 μg L?1 and 0.111–0.350 μg L?1, respectively, while 4-t-OP could be detected in only a few raw water samples with the concentration lower than its limit of quantitation (LOQ). The levels of BPA and 4-NP in raw water were significantly different among three hydrographic periods and the highest concentration can be observed in dry period. The difference in removal efficiency of BPA and 4-NP in seven water plants was also observed among three hydrographic periods, e.g. relative higher in dry period for BPA and in flow period for 4-NP. Potential risk assessment hinted that BPA and 4-NP in raw water showed a low to medium and a medium to high risk respectively to aquatic environment, while in tap water, the health risk from BPA and 4-NP could be ignored on human.  相似文献   

18.
A pilot study involving screening measurements of gross alpha/beta activity concentration in drinking water was performed in 12 cities with the highest population density in Albania. The aim of this study was to develop a first insight regarding the radiological quality of drinking and bottled water supplies. The tap and bottled water samples investigated are acceptable for consumption, complying with the WHO recommendations for drinking water. The average gross alpha and beta activity concentrations were \( 36_{ - 18}^{ + 37} \) and \( 269_{ - 150}^{ + 337} \)  mBq/L, respectively in tap waters. While for bottled water the gross alpha and beta activities were respectively \( 39_{ - 23}^{ + 55} \) and \( 220_{ - 132}^{ + 336} \)  mBq/L. The data obtained can provide information for authorities regarding the quality of drinking water and a baseline for future contaminations.  相似文献   

19.
浅论绿茶与乌龙茶氟含量对人体健康的影响   总被引:2,自引:0,他引:2  
分别用重蒸水和自来水,通过蒸煮法和浸泡法制出不同浓度的绿茶液和乌龙茶液,对比测定研究茶液中氟含量,结果表明,茶液中的氟含量随茶叶浓度增加而增加,且乌龙茶高于绿茶,当茶叶浓度超过10.0g/L时,茶液中的氟含量即超过国家饮水卫生标准,提示人们饮用水茶液浓度在5.0g/L左右为宜。  相似文献   

20.
Total reflection X-ray fluorescence spectrometry and chemical pre-concentration procedures have been applied for the analysis of trace concentrations of copper, mercury, and lead in drinking water samples. A simple total reflection module has been used in X-ray measurements. The elements under investigation were pre-concentrated by complexation using a mixture of carbamates followed by solvent extraction with methyl isobutyl ketone. The preconcentration procedure was tested with the use of twice-distilled water samples and samples of mineral and tap water spiked with known additions of copper, mercury, and lead. The obtained recovery and precision values are presented. The minimum detection limits for the determination of these elements in mineral and tap water samples were found to be 40 ng l−1, 60 ng l−1, and 60 ng l−1, respectively.  相似文献   

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