荧光光度法测定水和废水中的对硫磷和甲基对硫磷

有机磷农药对硫磷和甲基对硫磷在碱性水溶液中水解生成对硝基酚,用硼氢化钾将对硝基酚还原成能产生荧光的对氨基酚,以275nm为激发波长,在392nm处测定荧光强度,方法的检出限为3.0μg·L~(-1),回收率为90.5%,可应用于水和废水中两种农药的测定.     

多波长分光光度法测定对乙酰氨基酚合成过程中三组分含量

探讨了在ＨＣＬ体系中用双波长等吸收点分光光度法及系数倍率法同时测定对乙酰氨基酚合成过程中对硝基酚，对氧基酚和对乙酰氨酚三组分含量的可行性，对硝基酚的最大吸收为３１８ｎｍ，线性范围为０－３０ｍｇ／Ｌ；对乙酰基酚的测定波长为２４０ｎｍ，参比波长为３５８ｎｍ；对氨基酚的测定波长为２４０ｎｍ，３５８ｎｍ，３６１ｎｍ。     

二氧化硅/聚苯乙烯复合微球的制备及作为固相萃取填料的研究

以分散聚合法制备了二氧化硅/聚苯乙烯单分散复合微球,以红外光谱、透射电镜(TEM)、扫描电镜(SEM)等手段对其进行了表征。以合成的二氧化硅/聚苯乙烯作为固相萃取填料制作固相萃取小柱。通过固相萃取与液相色谱联用,测定了水中邻硝基酚、间硝基酚、对硝基酚和辛基酚、壬基酚,考察了固相萃取条件对固相萃取柱性能的影响,选择了最佳的色谱分离条件。结果表明,自制固相萃取小柱对水中硝基酚、烷基酚的萃取率高,与HPLC联用测定结果重现性好,邻硝基酚、间硝基酚、对硝基酚、辛基酚、壬基酚的最低检出限分别为0.90、0.72、0.62、0.38和0.41μg/L。     

基于甲基葡萄糖醛酸钠诱导下大肠杆菌的光度法快速检测研究

建立了一种快速检测大肠杆菌的光度分析法。在脱氧胆酸钠(DOC)培养基中,大肠杆菌被甲基葡萄糖醛酸钠(m ethyl-β-D-glucuron ide sod ium,M etG lu)诱导,在细菌体内产生特异性葡萄糖醛酸酶(-βD-glucu-ron idase)。通过膜渗透剂Polymyxin B nonapeptide hydrochloride(PBN)和Lysozym e对大肠杆菌细胞膜的作用,葡萄糖醛酸酶从大肠杆菌细胞中释放出来。葡萄糖醛酸酶能够催化分解底物p-N itrophenyl--βD-glucu-ron ide(PNPG)而产生对硝基酚,而对硝基酚的量与溶液中大肠杆菌的浓度成正比。对硝基酚对波长为400nm的可见光有最大吸收。根据吸光度值的大小与对硝基酚的浓度成很好的线性关系,通过测定400 nm处对硝基酚的吸光度值,实现了对大肠杆菌的快速定量检测。     

用超临界流体萃取和固相萃取分析水中酚类污染物

使用自制的超临界流体萃取仪，比较了从Ｃｈｒｏｍｏｓｏｒｂ，Ｐｏｒａｐａｒｋ和ＧＤＸ系列的８种吸附剂上萃取苯酚，邻硝基酚，邻氯酚，对氯酚，对二甲酚，２，４－二氯酚和２，４，６－三氯酚的回收率。并用萃取回收率比较高的ＧＤＸ－３０１富集１Ｌ酸性水样中１０＾－７ｇ／ｍＬ级的以上各酚，然后用超临界ＣＯ２脱附，回收率从３２．５％到９２．９％，同时还对超临界ＣＯ２脱附ＧＤＸ－３０１上各酚的操作条件进行了优化，并     

荧光硅量子点的合成及对水样中对硝基酚的检测

本文以3-氨丙基三乙氧基硅烷为硅源,对乙酰氨基酚为还原剂合成了水溶性青色荧光硅量子点(A-SiQDs),通过透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)及X射线光电子能谱(XPS)等手段对A-SiQDs进行了表征,合成的A-SiQDs最大激发和发射波长分别为398 nm和495 nm,稳定性好,荧光量子产率为12.8%,荧光寿命为5.71 ns。对硝基酚能导致A-SiQDs的荧光猝灭,建立了基于A-SiQDs荧光体系检测对硝基酚的方法,方法的线性范围为1～80μM,检出限为0.87μM。该方法简单,选择性好,可用于水样中对硝基酚的定量检测。     

Bu—NaOH萃取—反萃取体系测定水中的微量酚

用紫外四阶导数光谱直接测定水中的微量酚,曾有过报道,作者也研究了用四阶导数光谱法同时测定污水中酚类和芳胺,但方法的灵敏度都不太理想。本文是用醋酸丁酯萃取,5％NaOH反萃取,可测定酚0.03～11mg·L~(-1),并消除了许多物质的干扰。 1 试验部分 1.1 主要试剂与仪器 酚标准储备液及使用液:参照文献[3]配制 日立UV-557型双光束双波长分光光度计 pHS-3型酸度计 1.2 试验方法 定量移取适量水样,用HCl(1+1)调pH为2.0,移入250ml量瓶中稀释至刻度,然后移入500ml分液漏斗中。分别加入醋酸丁酯10ml萃取两次,合并有机相。有机相分别用NaOH溶液(5％)4ml、3ml反萃取两次,水相收集在10ml比色管中,用HCl(1+1)调pH为2.5+0.5。用紫外导数分光光度计在300～200nm     

三溴偶氮胂双波长分光光度法测定水中稀土的研究

本文研究了水中稀土的测定条件,用PMBP-醋酸丁酯在pH5.5时萃取分离稀土元素,继以0.1NHCl-0.03％8-羟基喹啉溶液反萃取稀土元素,用三溴偶氮胂双波长分光光度法测定,以试剂吸收峰波长525nm为参比波长,络合物吸收峰波长650nm为测量波长,可将灵敏度提高65％左右。本文对双波长法提高灵敏度的原因进行了新的理论解释。一、实验部分 (一)仪器和主要试剂: 1.721型分光光度计、pHS-2型酸度计。 2.稀土标准溶液:La_2O_3:CeO_2:Nd_2O_3:Y_2O_3=30:40:20:10.贮备液1mg/ml,使     

双浊点萃取-毛细管电泳法测定天然水中酚类化合物的研究

建立了双浊点萃取(dCPE)-毛细管电泳(CE)法测定天然水中酚类化合物的新方法。以Triton X-114为萃取剂,NaOH为反萃取剂,对苯酚、2,4,6-三氯苯酚和邻硝基苯酚进行双浊点萃取。考察了pH值、萃取剂浓度、平衡温度及时间和离子强度等因素对萃取率的影响。dCPE方法的优化条件为:pH=2.0、Triton X-114的浓度为0.14%(m/V)、平衡温度为40℃、平衡时间为10min、NaCl浓度为4.0%(m/V);电泳条件为:10mmol/L硼砂-磷酸钠缓冲溶液(pH=9.8)、电压18kV、检测波长210nm。在最优的条件下,苯酚、2,4,6-三氯苯酚、邻硝基苯酚的检出限(S/N=3)分别为0.10、0.15和0.18μg/mL;富集因子分别为24.0、19.3和20.1;相对标准偏差(RSD)分别为3.9%、2.6%和3.3%(c=2.0μg/mL,n=3)。     

HPLC法同时测定尿样中芳香族化合物的6种代谢产物

建立了同时测定尿样中反,反-粘康酸、马尿酸、苯乙醇酸、苯乙醛酸、对氨基酚和对硝基酚的高效液相色谱法(HPLC).优化了色谱分离及检测条件,并采用时间程序波长检测.确定了最佳样品预处理条件:以5 mL二氯甲烷-异丙醇(7∶3)为萃取溶剂;样品用量5 mL;NaCI加入量0.75 g;萃取时间2 min,分别在酸性和中性条...     

高吸水性树脂的吸水机理

高吸水性树脂是三度空间网络聚合物，是高分子电介质。在高分子网络链上嵌有可电离的离子对，遇水形成离子网络。该树脂能吸收自身重量几百倍至几千倍的水，且保水性好，即使在压力下，水也不从中溢出。其吸水机理可用Ｆｌｏｒｙ－Ｈｕｇｇｉｎｓ热力学公式来解释。     

Ion Product of Pure Water Characterized by Physics-Based Water Model

Pure water has been characterized for nearly a century, by its dissociation into hydronium (H₃O)¹⁺ and hydroxide (HO)^1- ions. As a chemical equilibrium reaction, the equilibrium constant, known as the ion product or the product of the equilibrium concentration of the two ion species, has been extensively measured by chemists over the liquid water temper-ature and pressure range. The experimental data have been nonlinear least-squares fitted to chemical thermodynamic-based equilibrium equations, which have been accepted as the industrial standard for 35 years. In this study, a new and statistical-physics-based water ion product equation is presented, in which, the ions are the positively charged protons and the negatively charged proton-holes or prohols. Nonlinear least squares fits of our equation to the experimental data in the 0-100 ℃ pure liquid water range, give a factor of two better precision than the 35-year industrial standard.     

Spectral Irradiance in Pond Water: Influence of Water Chemistry

Knowing the depth of UV penetration in ponds and the chemical variables that control underwater spectral irradiance is a prerequisite to predicting the influence of UV on amphibians and other pond organisms. The present study found that over 99% of UVB (280–315 nm) radiation was attenuated in the top 10–20 cm of ponds sampled on the edge of the Canadian Shield near Peterborough, Ontario. While the principal attenuating substance was, as in lakes, dissolved organic carbon (DOC), neither DOC nor DOC fluorescence were useful predictors of the attenuation coefficients other than the observation that all values of DOC were high and all attenuation coefficients were also high. The lack of a reliable relationship between DOC and attenuation resulted from differences throughout the season in the fraction of the DOC capable of absorbing radiation (chromophores) and the fraction capable of fluorescing (fluorophores). Attenuation was higher than predicted from DOC during springtime when amphibians lay their eggs. Absorbance coefficients measured using a spectrophotometer proved to be reliable predictors of both UVB and UVA attenuation coefficients measured in the ponds with a spectro-radiometer. While DOC provides an effective sun screen against the direct damage of UV radiation, the high attenuation means that the photochemical activity spread over at least 15 m in the ocean is confined to only a few centimeters in ponds.     

Improvement of Atmospheric Water Surface Discharge with Water Resistive Barrier

Atmospheric water surface discharge is a promising method for water treatment. The selection of discharge gap distance must take a pair of conflicting aspects into account: the chemical efficiency grows as the discharge gap distance decreases, while the spark breakdown voltage decreases as the gap distance decreases. To raise the spark breakdown voltage and the chemical efficiency of atmospheric pressure water surface discharge, resistive barrier discharge is introduced in this paper. Both the high voltage electrode and the ground electrode are suspended above water surface to form an electrode-water-electrode discharge system. The water layer plays the role of a resistive barrier which inhibits the growth rate of discharge current as voltage increases. Experiments conducted at different discharge gap distances and water conductivities indicate that both the spark breakdown voltage and the chemical efficiency are remarkably raised in comparison with traditional water surface discharge. After parameter optimization, the discharge reactor is scaled up with activated carbon fiber electrodes and advantages of water resistive barrier discharge are kept.     

Water vapor polarization

The characteristics of water vapor polarization were calculated, and several polarization theory equations applicable to different states of aggregation of molecular systems were obtained.     

Water trimer cation

By using density functional theory (DFT) and high-level ab initio theory, we have investigated the structure, interaction energy, electronic property, and IR spectra of the water trimer cation [(H₂O) ₃ ⁺ ]. Two structures of the water trimer cation [the H₃O⁺ containing linear (3Lp) structure versus the ring (3OO) structure] are compared. For the complete basis set (CBS) limit of coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)], the 3Lp structure is 11.9?kcal/mol more stable than the 3OO structure. This indicates that the ionization of water clusters produce the hydronium cation moiety (H₃O⁺) and the hydroxyl radical. It is interesting to note that the calculation results of the water trimer cation vary seriously depending on the calculation level. At the level of M?ller?CPlesset second-order perturbation (MP2) theory, the stability of 3OO is underestimated due to the underestimated O??O hemibonding energy. This stability is also underestimated even for the CCSD(T) single point calculations on the MP2-optimized geometry. For the 3OO structure, the MP2 and CCSD(T) calculations give closed-ring structures with a hemi-bond between two O atoms, while the DFT calculations show open-ring structures due to the overestimated O??O hemibonding energy. Thus, in order to obtain reliable stabilities and frequencies of the water trimer cation, the CCSD(T) geometry optimizations and frequency calculations are necessary. In this regard, the DFT functionals need to be improved to take into account the proper O??O hemibonding energy.     

用肥皂水区分软水和硬水的实验探究

肥皂水的质量分数、用量,水的硬度和温度等因素,都会影响“用肥皂水区分软水和硬水” 的实验效果。在常温下,肥皂水遇硬水既可以形成浮渣,也可以分散浮渣;温度过高时,肥皂水遇硬水不会产生浮渣,但会产生泡沫。利用肥皂水不仅可以比较出日常生活中不同水的硬度,还可以使硬水软化。     

纯水与自来水中氰离子的比色检测

设计合成了水溶性比色传感器磺酸功能化的偶氮水杨醛吖嗪(S),其结构经由1H NMR,ESI-MS确证.S在纯水与自来水中对氰离子(CN-)具有专一选择性的比色检测能力,最低检出限分别为0.16和0.63 μmol/L.可逆的质子转移检测机制赋予S循环再利用的优势,借助于检测试纸,实现了 CN-可逆的比色检测.该工作为纯...