原子吸收法测定环境水样中化学需氧量

在Ｈ２ＳＯ４介质中用Ｋ２Ｃｒ２Ｏ７同ＣＯＤ水样反应,反应后水相中过量的Ｃｒ（Ⅵ）以Ｃｒ２Ｏ２－７形式被ＴＯＡ萃入有机相中,而生成的Ｃｒ（Ⅲ）则留在水相,用ＡＡＳ测定有机相中的Ｃｒ（Ⅵ）或水相中的Ｃｒ（Ⅲ）都可求得ＣＯＤ含量。本法简便快速、需样量少、且测定结果同标准方法（ＣＯＤＣｒ法）一致,回收率为９８％～１０８％,平均标准偏差为３．３％。     

Kam insky型催化剂催化乙烯齐聚──二酚基二茂锆的催化作用

通过改变 Ａｌ／ Ｚｒ 比、反应温度及反应时间, 分别考察了 Ｃｐ２ Ｚｒ（ Ｏ Ａｒ）２／ Ｅ Ａ Ｏ （ Ａｒ＝ Ｃ６ Ｈ５、ｐ  Ｃ６ Ｈ４ Ｍ ｅ、ｍ  Ｃ６ Ｈ４ Ｎ Ｏ２、ｐ  Ｃ６ Ｈ４ Ｎ Ｏ２） ４ 种体系对乙烯齐聚的催化作用． 发现用 Ｃｐ２ Ｚｒ（ Ｏ Ａｒ）２ 代替 Ｃｐ２ Ｚｒ Ｃｌ２ 作为主催化剂, 对于 Ｋａｍ ｉｎｓｋｙ 型体系 Ｃｐ２ Ｚｒ Ｌ２／ Ｅ Ａ Ｏ 催化乙烯齐聚, 具有调变作用,在提高催化活性的同时, 可使低碳烯烃的选择性明显改善． 在 Ｃｐ２ Ｚｒ（ Ｏ Ａｒ）２／ Ｅ Ａ Ｏ 的４ 种催化体系中, 当酚基对位带有强吸电子基团时（ Ａｒ＝ ｐ  Ｃ６ Ｈ４ Ｎ Ｏ２）, 对乙烯齐聚的催化性能最佳．     

用微芯片实现流动注射化学发光方法测定水样中铬(Ⅲ)

在微化学反应器上首次实现了流动注射Ｃｒ（Ⅲ）－鲁米诺－Ｈ２Ｏ２化学发光反应测定,并定量测试水样中微量Ｃｒ（Ⅲ）,检出限达到１０＾－７ｍｏｌ／Ｌ。     

某些离子对Cr_2O_7~（2－）阳极形成过程的影响

某些离子对Ｃｒ_２Ｏ_７~（２－）阳极形成过程的影响金世雄,周志刚,王岚（南开大学化学系,天津３０００７１）Ｃｒ（Ⅲ）阳极氧化为Ｃｒ（Ⅵ）是工业制取铬酸及其盐类的主要方法,也是从含铬工业废水中回收Ｃｒ（Ⅵ）的主要途径．文献￣［１］曾表明,Ｃｒ（Ⅲ）的阳?..     

流动注射化学发光同时测定废水中的三价铬和六价铬

首次将镀铜锌粒作成优良的还原柱，在线还原Ｃｒ（Ⅵ）成Ｃｒ（Ⅲ），以鲁米诺－Ｈ２Ｏ２（ＫＢｒ）体系流动注射化学发光同时测定废水中两种价态的铬。分析速率为６０试样／ｈ；线性范围为１．０×１０＾－５－１．０×１０＾－９ｍｏｌ／Ｌ；测Ｃｒ（Ⅲ）及Ｃｒ（Ⅵ）的相对标准偏差（ｎ＝６）分别为０．３７％－４．０％及１．２％－４．４％；测定Ｃｒ（Ⅲ）的检出限２．３×１０＾－１１ｍｏｌ／Ｌ。测定结果与标准方法无显差     

Kaminsky型催化剂化乙烯齐聚：二酚基二茂锆的催化作用

通过改变Ａｌ／Ｚｒ比,反应温度及反应时间,分别考察了Ｃｐ２Ｚｒ（ＯＡｒ）２／ＥＡＯ（Ａｒ＝Ｃ６Ｈ５、ｐ－Ｃ６Ｈ４Ｍｅ、Ｍ－ｃ６ｈ４ｎｏ２、Ｐ－ｃ６ｈ４ｎｏ２）４种体系对乙烯齐聚的催化作用,发现用Ｃｐ２Ｚｒ（ＯＡｒ）２代替Ｃｐ２ＺｒＣｌ２作为主催化剂,对于Ｋａｍｉｎｓｋｙ型体系Ｃｐ２ＺｒＬ２／ＥＡＯ催化乙烯齐聚,具有调变作用,在提高催化活性的同时,可使低碳烯烃的造反     

新型四胺大环锌（Ⅱ）配合物的晶体结构

１，４，７，１０－四氮杂环十二烷（ｃｙｃｌｅｎ）与２－氯甲基吡啶反应获得新型八齿配体１，４，７，１０－四（２－甲基吡啶基）－１，４，７，１０－四氮杂环十二烷（Ｌ）。该配体与Ｚｎ（ＣｌＯ＿４）＿２在水溶液中反应生成无色晶体ＺｎＬ（ＣｌＯ＿４）＿２（１）。晶体结构测定表明：化合物１，Ｃ＿３２Ｈ＿４０－Ｃｌ＿２Ｎ＿８Ｏ＿８Ｚｎ，属单斜晶系，空间群Ｐ２＿１／ｃ，α＝９．８２２（５），ｂ＝１０．７２１（３），ｃ＝３３．９００（２）Ａ，β＝９０．５４（４）°，Ｖ＝３５７０（４）Ａ３，Ｄ＿ｃ＝１．４９ｇ／ｃｍ￣３，Ｚ＝４，Ｆ（０００）＝１６６４，Ｍｒ＝８０１．０。１８８８个可观测衍射点参与修正，Ｒ＝０．０６９，Ｒｗ＝０．０７２。在化合物１中，Ｚｎ原子采取六配位的变形八面体构型，在４个吡啶侧臂之中，只有相对的两个参与配位，而另外的两个有一个远离配位中心，另一个吡啶上的氮原子与锌原子之间存在因二级化学键而引起的弱相互作用。     

Skeleton Vibrations and Force Constants of ［Fe_2Cr（μ_3－O）（glycine）_6（H_2O）_3］（NO_3）_7．3H_2O

ＳｋｅｌｅｔｏｎＶｉｂｒａｔｉｏｎｓａｎｄＦｏｒｃｅＣｏｎｓｔａｎｔｓｏｆ［Ｆｅ_２Ｃｒ（μ_３－Ｏ）（ｇｌｙｃｉｎｅ）_６（Ｈ_２Ｏ）_３］（ＮＯ_３）_７．３Ｈ_２ＯＺｈａｎｇＬｉｎ－Ｎａ，ＬｉｎＺｈｅｎｇ－Ｙａｎ（ＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏ...     

含TBP的PS－EC复合膜微胶囊的制备及对Cr_2O_7~（2－）传输的研究

将聚苯乙烯（ＰＳ）和乙基纤维素（ＥＣ）溶于ＣＨ_２Ｃｌ_２中，利用水中干燥法制备ＰＳ－ＥＣ复合膜微胶囊。当复合膜的微孔中含有磷酸三丁酯（ＴＢＰ）时，微胶囊膜对Ｃｒ_２Ｏ_７~（２－）具有传输功能。芯材采用高浓度ＮａＯＨ时，可使Ｃｒ_２Ｏ_７~（２－）逆浓差传输。研究了ＰＳ和ＥＣ的比例、微胶囊粒径、ＮａＯＨ浓度及ＴＢＰ含量对传输的影响．在适当条件下，１０ｍｉｎ内Ｃｒ_２Ｏ_７~（２－）的浓度由１×１０~（－４）ｍｏｌ／Ｌ降至１×１０~（－７）ｍｏｌ／Ｌ以下。     

碳氟醇对阳离子表面活性及胶团反离子结合度的影响

用表面张力及电动势法研究了Ｃ１０Ｈ２１Ｎ（ＣＨ３）３Ｂｒ，Ｃ１２Ｈ２５Ｎ（ＣＨ３）３Ｂｒ和Ｃ３Ｆ７ＣＨ２ＯＨ混合水溶液的表面与胶团性质。结果表明，对于阳离子表面活性剂，Ｃ３Ｆ７ＣＨ２ＯＨ的加入一方面增加表面活性，另一方面降低胶团反离子结合度。后者不同于阴离子表面活性剂／Ｃ３Ｆ７ＣＨ２ＯＨ混合体系，可归因于Ｃ３Ｆ７ＣＨ２ＯＨ略有酸性，因而具备一些类似阴离子表面活性剂的性质。     

Advantages and analytical applications of chloride generation. A review on vapor generation methods in atomic spectrometry

This review summarizes and discusses the analytical methods and techniques more frequently described in the literature for vapor generation as a mode of sample introduction into atomization/excitation cells. The volatile compounds have been classified into the following classes: hydrides, oxides, chelates, alkyls and halides. To estimate the well-established trends and tendencies, some representative papers devoted to vapor generation are mentioned. Special emphasis is given to discuss the advantages and analytical applications of chloride generation.     

Tunable UV generation at 283 nm by frequency doubling and sum frequency mixing of two semiconductor lasers for the detection of Pb

High resolution atomic absorption measurements of lead at 283 nm in a vapor cell were performed by frequency doubling an 850 nm laser diode to obtain 425 nm light, followed by sum frequency generation of the harmonic radiation with a second 850 nm laser diode.     

UV photochemical vapor generation-atomic fluorescence spectrometric determination of conventional hydride generation elements

A systematic investigation of UV photochemical vapor generation (photo-CVG) and its potential application for seven typical hydride-forming elements (As, Sb, Bi, Te, Sn, Pb and Cd) when combined with atomic fluorescence spectrometry (AFS) detection is presented. These analyte ions were converted to volatile species following UV irradiation of their aqueous solution to which low molecular weight organic acids (such as formic, acetic or propionic acid) had been added, and introduced to an atomic fluorescence spectrometer for subsequent analytical measurements. The experimental conditions for photo-CVG and the interferences arising from concomitant elements were carefully investigated. Limits of detection as low as 0.08, 0.1, 0.2 and 0.5 ng mL^− 1 were obtained for Te, Bi, Sb and As, respectively, comparable to those by hydride generation-AFS. The RSDs obtained with the proposed method for these elements were better than 5% at 50 ng mL^− 1. It is noteworthy that the presence of TiO₂ nanoparticles combined with UV irradiation remarkably enhances the CVG efficiencies of Se(VI) and Te(VI), which cannot form hydrides with KBH₄/NaBH₄. Moreover, photo-CVG has a greater tolerance toward interferences arising from transition elements than hydride generation, and this facilitates its application to the analysis of complicated sample matrices.     

Critical evaluation of the application of photochemical vapor generation in analytical atomic spectrometry

Chemical vapor generation (CVG) is a widely adopted sample introduction method for analytical atomic spectrometry. Nonvolatile precursors (usually ionic, metallic or organometallic species) can be transferred from the condensed phase to the gas phase, yielding the advantages of efficient matrix separation, high analyte transport efficiency, high selectivity, simple instrumentation, and ease of automation. Hydride generation enjoys the greatest popularity as a consequence of its ease of implementation, fast reaction and high yield; but photo-CVG, a newly emerging research field in analytical chemistry, may provide a powerful alternative to conventional CVG due to its simplicity, versatility and cost effectiveness. Although photocatalytic pre-reduction has been used for a number of years, the most attractive aspect of this newly emerging area is the direct generation of volatile species using photochemical reactions. Recent studies undertaken with flow through and batch reactors employing low molecular weight organic acids as photochemical agents are highlighted in this study for such systems as mercury and selenium, as well as reaction mechanisms considered for these processes. Discussion is focused on recent advances in photo-CVG, which we believe will become the subject of intensive future research initiatives.     

Multifunctional Molecular Material Combining Photocurrent Generation and Second-Order Optical Nonlinearity in LB Monolayer Films

ＩｎｔｒｏｄｕｃｔｉｏｎＭｏｌｅｃｕｌａｒｎｏｎｌｉｎｅａｒｏｐｔｉｃｓ (ＮＬＯ)ｈａｓａｔｔｒａｃｔｅｄｉｎ ｃｒｅａｓｉｎｇｉｎｔｅｒｅｓｔｏｖｅｒｔｈｅｐａｓｔｔｅｎｙｅａｒｓ ,ｂｅｃａｕｓｅｏｆｔｈｅｉｒｐｏｔｅｎｔｉａｌａｐｐｌｉｃａｔｉｏｎｓｉｎｖａｒｉｏｕｓｆｉｅｌｄｓｉｎｃｌｕｄｉｎｇｔｅｌｅｃｏｍ ｍｕｎｉｃａｔｉｏｎｓ ,ｏｐｔｉｃａｌｄａｔａｓｔｏｒａｇｅａｎｄｐｒｏｃｅｓｓｉｎｇａｎｄｏｐｔｉ ｃａｌｐｏｗｅｒｌｉｍｉｔａｔｉｏｎ .1,2 Ｉｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｔｈｅｐ…     

A Theoretical Investigation of Surface‐enhanced Sum‐frequency Generation

Following the surface enhanced Raman scattering (SERS), we shall investigate the possibility of observing surface‐enhanced sum‐frequency generation (SESFG), which refers to the transformation of ordinary vibrational SFG (i.e. singly resonant) into SESFG. Two mechanisms of SESFG will be studied; one is due to the transformation of singly‐resonant vibrational SFG into doubly resonant vibrational SFG (that is, both vibrationally resonant and Raman‐scattering resonant) and the other is due to the enhancement of the polarizability in addition to the original vibrational resonance in vibrational SFG.     

氢化物发生-电感耦合等离子体原子发射光谱法测定环境样品中痕量硒

环境样品经硝酸-过氧化氢-氢氟酸体系微波消解,利用自制雾化器采用氢化物发生-电感耦合等离子体原子发射光谱法测定其中的痕量硒。选择硒的分析谱线为196.090nm。硒的质量浓度在32μg·L-1以内与其发射强度呈线性关系,方法的检出限(3S/N)为0.71μg·L-1。方法应用于国家标准物质中硒的的测定,测定值与认定相符,加标回收率在85.8%~102%之间,测定值的相对标准偏差(n=6)在0.38%~2.3%之间。     

Mechanism of generation of volatile species by aqueous boranes: Towards the clarification of most controversial aspects

The state of knowledge of the mechanisms involved in the chemical generation of volatile species (CHG) arising from aqueous phase reaction of classical hydride forming elements, transition and noble metals with borane complexes (mainly NaBH₄), has been critically reviewed in the light of evidences and literature data published in the last fifty years. The mechanisms, which are necessary to describe the reactivity of CHG system, are essentially: (i) the mechanism of hydrolysis of borane complexes, (ii) the mechanism of formation of volatile species, (iii) the mechanism of liquid phase interference and (iv) the mechanism of action of additives. Only the mechanisms (i) and (ii) have reached a good degree of rationalization, whereas more experimental evidences are necessary for the mechanisms (iii) and (iv). A more general reaction model for analytical CHG can be drawn according to the present state of knowledge, which is valid for both classical hydride forming elements and transition and noble metals. It is based on the formation of analyte–borane complex (ABC) intermediates through which takes place the direct, stepwise transfer of hydrogen atoms from boron to analyte substrate ML_n, (M is a metal or semi-metal, L is a ligand). By this way the original analyte substrate is stepwise converted to hydrido metal complexes MH_xL_y, then to the final products (hydride, metal atoms, etc). The clarification of several controversial aspects and the ruling out of wrong concepts, among them the “nascent” hydrogen theory, can been achieved in the light of the present state of knowledge.     

电感耦合等离子体原子发射光谱法研究锗的氢化反应机理

采用氢化物连续发生－ＩＣＰ－ＡＥＳ法研究了锗的氢化反应中各反应物之间的摩尔关系及其与锗烷产率之间的关系，提出锗的氢化反应是由中和反应所诱导或催化的反应机理，确定获得最大锗烷产率的酸碱浓度匹配原则。     

Molecular origins of the remarkable chiral sensitivity of second-order nonlinear optics.

Recent observations of remarkably large chiroptical effects in second-harmonic generation (SHG) and sum-frequency generation (SFG) measurements suggest exciting possibilities for the development of new chiral-specific spectroscopies and novel chiral materials for nonlinear optics. Several fundamental studies designed to elucidate the molecular and macromolecular origins of the chiral responses are reviewed to provide a framework for development of this emerging field. In general, the chiral activity in SHG and SFG has the potential to arise from complex interactions between hosts of different competing effects. Fortunately, relatively simple electric dipole-allowed mechanisms routinely dominate the nonlinear optical chiral activities of most practical systemsexpressions can often be generated to link the. This substantial reduction in complexity allows for the development of simple models connecting the macroscopic nonlinear optical response to intuitive molecular and supramolecular properties.