近年国内固相萃取-色谱分析的进展

对近两年国内各个领域的学者在使用固相萃取做样品前处理的色谱分析方面的研究和应用作了综述, 这一综述包括10个部分: 1. 国内近两年有关固相萃取的综述报告;2. 固相萃取-色谱分析在水质分析中的应用;3. 固相萃取-色谱分析在奶制品和肉类食品分析中的应用;4. 固相萃取-色谱用于蔬菜和水果中有害物质分析的应用;5. 固相萃取-色谱用于粮食和其他食品中有害物质分析的应用;6. 固相萃取-色谱在血药浓度、体液及组织中有害物质分析中的应用;7. 固相萃取-色谱在药物分析中的应用;8. 固相萃取-色谱在其他使用色谱分析中的应用;9. 基质固相分散在色谱分析中的应用;10. 分子印迹SPE在样品前处理中的应用.     

第53届国际化学奥林匹克试题

通则 ● 只能用墨水笔回答问题.只能使用非编程计算器. ● 考试时间5小时.一共有9道题.你可以按照任何顺序回答问题. ● 只有在开始(START)指令发出后,才可以开始(Begin)答题. ● 所有结果必须用墨水笔书写在答题纸指定的相应答题框中.可以在试卷的背面打草稿.谨记写在答题框外的答案不予评判. ● 相关的计算须写在指定的答题框中.只有写出过程且得出正确答案的才能得满分. ● 在停止(STOP)命令发出前30分钟,监考人员将给予提醒. ● 当停止(STOP)命令发出后,必须立即停止答题.若不停止书写,将导致你的考试无效. ● 为准确理解题意,可向监考老师索要英文原版试卷. ● 未经允许,不许离开座位.如果需要帮助(如计算器有问题,需要去洗手间,等等),请举手,待监考老师过来.     

离子色谱法同时测定果汁中20种有机胺、生物胺和阳离子

建立了梯度淋洗-电导抑制-离子色谱法测定果汁中20种有机胺、生物胺和阳离子的方法,通过对流速、色谱柱温度、p H等因素的考察,探索出了适合20种组分测定的多级梯度淋洗条件。结果表明,当流速为0. 25 mL/min,pH在3. 5～4. 5,柱温在40℃时,20种组分在0. 05～2. 00 mg/L浓度范围内具有良好的线性关系(R 0. 99)。20种组分检出限(S/N=3)在0. 0006～0. 0503 mg/L之间;在0. 10,0. 20,1. 00 mg/L 3个添加浓度水平下,回收率为78. 4%～108. 9%,相对标准偏差(RSDs)在2. 1%～7. 3%之间。该方法适用于果汁中20种有机胺、生物胺和阳离子的分析测定。     

HPLC-ESI-QTOF-MS法测定减肥保健食品中16种食欲抑制剂

建立高效液相色谱-电喷雾离子化-四级杆串联飞行时间质谱法(HPLC-ESI-QTOFMS)高通量快速测定减肥保健食品中16种食欲抑制剂的含量。样品经甲醇超声萃取、Oasis MCX固相萃取柱净化,以甲醇和有乙酸铵溶液为流动相,梯度洗脱,采用QTOF-MS质谱仪进行分析。结果表明:16种食欲抑制剂在1. 0～100. 0 ng/mL范围内具有良好的线性关系,相关系数≥0. 9995;方法检出限在0. 03～0. 30μg/kg,方法定量限在0. 10～1. 00μg/kg;加标回收率在91. 7%～99. 2%,相对标准偏差在1. 1%～3. 9%。     

有机合成的新技术

在进行有机合成时,常因溶液中混合在一起的各种反应物分子自由碰撞发生副反应,而大大降低了所需要的产物的产率。以色列Weizmann科学研究所的B.J.Cohen,M.A.Krau8和A.Patehornik将几个反应物分别连接在各个磨成珠状的聚苯乙烯上,使在通常情况下极     

乙基醋酸纤维素溶致性液晶的研究

乙基醋酸纤维素溶于三氟乙酸、二氯乙酸、醋酸中.在浓度大于临界浓度时,形成胆甾型液晶态.溶液随浓度的增加,从各向同性态经两相共存转变成液晶态.在加热液晶溶液时,溶液转变成各向同性态.降低温度,液晶相再生成.在形成液晶过程中,存在过冷现象.在一定的条件下,液晶相以球状的形式存在.溶液的双折射△n在两相共存与完全液晶态间相互转变时会发生较大变化.乙基醋酸纤维素大分子链的刚性随有机酸溶剂体系的酸强度的增大而增大,使临界浓度C_1~*随溶剂酸强度的增大而减小.     

亚砜类非离子型表面活性剂在固/液界面上的吸附I: 硅胶/水溶液界面上的吸附

测定了癸基和辛基-甲亚基亚砜在硅胶/水溶液界面的吸附以及溶液在石英界面的接触角. 研究了温度和pH值对吸附的影响. 吸附等温线似应归入Giles分类的L4型. 饱和吸附层的平均分子面积为27-30A^2. 二个同系物的γ/γ-c/cmc曲线彼此重叠. 吸附温度系数在低浓度范围是负性的在高浓度范围是正性的. 接触角的测量表面吸附使硅胶表面疏水. 从实验结果考虑到吸附过程由二个阶段组成: 一是在低浓度范围由固体表面和亚砜基之间的相互作用, 另一过程是在高浓度范围中, 被吸附的表面活性剂分子及其在溶液中的疏水作用.     

第四届冬季等离子体光谱会议1986年1月3日至10日在夏威夷召开

由“ICP Information Newsletter”刊物主办的两年一度的等离子体光谱会议将在美国夏威夷Kaanapali海滩Maui Surf饭店召开。本届会议是以ICP、DCP和MIP各类等离子体光源为重点,邀集在分析应用、基本理论和仪器方面有丰富经验的各国科学家进行讨论。优秀的论文将在会议上宣读和印发,并在评阅后提交“Spectrochimica Acta”发表。会议将组织下列专题讨论:(1)ICP-MS(R.S.Houk主持);(2)样品引入和传输技术(R.F.Browner,J.E.Meinhard);(3)干扰问题(L.M.Faires)(4)ICP-AFS(N.Omenetto);(5)分析应用(H.Taylor和K.Fuwa);(6)原子化过程(A.T.Zander);(7)等离子体过程控制和仪器(M.Routh和G.Meyer);(8)激发机理和等离子体特性(M.Blades);(9)色谱分     

多孔电极在电化学体系中的应用

查全性教授是中国现代电化学的奠基人之一. 在他的带领下,武汉大学化学系电化学研究室在基础电化学和应用电化学领域取得了卓越的成绩. 查教授及同事们在过去几十年里,栽培学生无数. 后来,一部分学生有幸成为推动世界电化学学科发展的中坚力量. 在这篇综述中,作者将概述查教授及同事们在电化学领域打下的夯实基础,及作者在多孔电极方向的研究进展. 本文的所有作者均于不同时期毕业于武汉大学. 站在巨人的肩膀上,我们实属荣幸！     

碳糊电极阳极吸附伏安法测定环丙沙星

报道了用碳糊电极阳极吸附伏安法测定环丙沙星的新方法.在 0. 40mol/L的NH4Ac HAc(pH4. 30)缓冲液中,使用JP 303极谱分析仪,环丙沙星在碳糊电极 (CPE)上有一灵敏的吸附伏安氧化峰,峰电位为1. 12V(vs.SCE).该氧化峰的二阶导数峰电流与环丙沙星的浓度在 8. 0×10-9 ~8. 0×10-7 mol/L(富集 90s)范围内成良好的线性关系,相关系数为 0. 998 8,检出限为 4. 0×10-9 mol/L(S/N=3,富集 110s).探讨了环丙沙星在碳糊电极上的伏安性质和电极反应机理,并且成功应用于人体尿样中环丙沙星含量的测定.加入回收实验,回收率在95. 5%至 103. 9%之间.     

Synthesis,fluorescence properties,and conformational analysis of ether-linked (1,8)pyrenophanes

Mono-, di- and oligo-ether linked (1,8)pyrenophanes 1–7 were synthesized, and their fluorescence and conformational properties in the absence and presence of metal ions were elucidated. Fluorescence spectra of 1.0 × 10⁻⁵ M solutions of the mono- and di-ether linked pyrenophanes 1–5 were comprised of only monomer emission bands, while those of the oligoethylene glycol linked analogs 6 and 7 contained both monomer and intramolecular excimer emission bands. Addition of perchlorate salts of Ba²⁺, Na⁺ and Li⁺ to 1:1 v/v CH₃CN:CH₂Cl₂ solutions of 6 and 7 caused decreases in the intensities of the corresponding intramolecular excimer emission bands and, in some cases, increases in the intensities of the monomer emission. Monomer and intramolecular excimer emission from the (1,8)pyrenophanes are suggested to arise from the respective anti and syn conformers, whose ratios are dependent on solvent polarity, temperature and kinds of added metal ions.     

Haloalkane adsorption into 1-D ensembles’ channels: Zn(II) coordination polymers

Abstract

Self-assembly of ZnX₂ (X^–?=?Cl^–, Br^–, and I^–) with 2,7-bis(isonicotinoyloxy)naphthalene (L) in a mixture of ethanol and dichloromethane yields 1-D zigzag chains of [ZnX₂L·2CH₂Cl₂]_n composition. The 1-D chains form an ensemble constituting hydrophobic suprachannels of 4.0–4.4?×?4.4–5.0 Ų with repeat units of ZnL for [ZnCl₂L] and [ZnBr₂L], and those of 5.2?×?12.0 Ų with repeat units of Zn₂L₂ for [ZnI₂L] in the appropriate arrays via C–H···π and π···π interactions. The most interesting feature is that alcohol molecules are not incorporated into the haloalkane-philic channels. That is, the channels discriminate haloalkanes from alcohols. Furthermore, the exchange of solvate molecules in a crystalline state indicates that the unique channels show different absorptions of haloalkanes such as CH₂Cl₂, CH₂Br₂, CH₂I₂, CHCl₃, 1,2-dichloroethane, and 1,2-dibromoethane.     

Kinetics of the reactions of Cl atoms with CH3Br and CH2Br2

The rate coefficients for the reactions of Cl atoms with CH₃Br, (k₁) and CH₂Br₂, (k₂) were measured as functions of temperature by generating Cl atoms via 308 nm laser photolysis of Cl₂ and measuring their temporal profiles via resonance fluorescence detection. The measured rate coefficients were: k₁ = (1.55 ± 0.18) × 10^?11 exp{(?1070 ± 50)/T} and k₂ = (6.37 ± 0.55) × 10^?12 exp{(?810 ± 50)/T} cm³ molecule^?1 s^?1. The possible interference of the reaction of CH₂Br product with Cl₂ in the measurement of k₁ was assessed from the temporal profiles of Cl at high concentrations of Cl₂ at 298 K. The rate coefficient at 298 K for the CH₂Br + Cl₂ reaction was derived to be (5.36 ± 0.56) × 10^?13 cm³ molecule^?1 s^?1. Based on the values of k₁ and k₂, it is deduced that global atmospheric lifetimes for CH₃Br and CH₂Br₂ are unlikely to be affected by loss via reaction with Cl atoms. In the marine boundary layer, the loss via reaction (1) may be significant if the Cl concentrations are high. If found to be true, the contribution from oceans to the overall CH₃Br budget may be less than what is currently assumed. © 1994 John Wiley & Sons, Inc.     

On‐line Liquid‐liquid Extraction Coupled to a Reversed Micellar‐mediated Chemiluminescence Detection System: Application to the Determination of Amino/Nitroaromatic Compounds

A simple and fast flow method for the trace level determination of p‐toluidine, 2‐methyl‐5‐nitroaniline, and 2,4‐dinitroaniline in aqueous samples is reported. These amino/nitroaromatics are related to trinitrotoluene (TNT) and appear during the degradation process of the explosive. The chemical principles of ion‐pair formation and liquid‐liquid extraction are applied: In aqueous acidic medium, the protonated analyte [HA]⁺ makes an ion‐pair with the tetrachloroaurate(III) ion, followed by on‐line ion‐pair extraction into the dichloromethane carrier used. After membrane separation, the CH₂Cl₂ containing the ion‐pair, [HA]⁺[AuCl₄]⁻, is mixed with the reversed micellar luminescent reagent of luminol (in 0.3 M Na₂CO₃) prepared from cetyl‐trimethylammonium chloride in CH₂Cl₂‐cyclohexane and the [AuCl₄⁻‐luminol chemiluminescence (CL) output is recorded. The detection limits (S/N> 3) are: p‐toluidine, 1.0 × 10⁻⁴M; 2‐methyl‐5‐nitroaniline, 1.0 × 10⁻⁷ M; 2,4‐dinitroaniline, 1.0 × 10⁻⁷ M, while the calibration curves are linear between 1.0 × 10⁻⁴ — 1.0 × 10⁻² M for all the compounds. Although spectral studies indicated the formation and extraction of a very small amount of the ion‐pair species, the reversed micellar‐mediated CL detection system provides an alternative procedure for the determination of degradation products of the explosive TNT in environmental aqueous samples.     

The polymerization of isobutylene by AlCl3 in CH2Cl2 and the role of CH2Cl2 in the initiation reaction

A solution of AlCl₃ in CH₂Cl₂ prepared in advance was used 18 days after the mixing of the components as an initiation system in the polymerization of isobutylene performed in CH₂Cl₂ in the temperature range between ?10 and ?20°C. The ¹H-NMR analysis of polyisobutylene (PIB) samples synthesized to low and high conversion showed that it is the initiation reaction and not the transfer reaction to dichloromethane that is responsible for the ? CH₂Cl endgroup in the polymer chain. In case of the transfer to monomer formation of PIB with internal terminal unsaturation [PIB? CH?C(CH₃)₂] is preferred to external unsaturation [PIB? CH₂(CH₃)C?CH₂]. The solutions of AlCl₃ in CH₂Cl₂ showed an absorption band at λ_max = 302 nm.     

Deactivation of I(2P1/2) by CH3Cl,CH2Cl2, CHCl3, CCl3F,and CCl4

Collisional deactivation of I(²P_1/2) by the title compounds was investigated through the use of the time-resolved atomic absorption of excited iodine atoms at 206.2 nm. Rate constants for atomic spin-orbit relaxation by CH₃Cl, CH₂Cl₂, CHCl₃, CCl₃F, and CCl₄ are 3.1±0.3×10⁻¹³, 1.28±0.08×10⁻¹³, 5.7±0.3×10⁻¹⁴, 3.9±0.4×10⁻¹⁵, and 2.3±0.3×10⁻¹⁵cm³ molecule⁻¹ s⁻¹, respectively, at room temperature (298 K). The higher efficiency observed for relaxation by CH₃Cl, CH₂Cl₂, and CHCl₃ reveals a contribution in the deactivation process of the first overtone corresponding to the C(SINGLEBOND)H stretching of the deactivating molecule (which lies close to 7603 cm⁻¹) as well as the number of the contributing modes and certain molecular properties such as the dipole moment. It is believed that, for these molecules, a quasi-resonant (E-v,r,t) energy transfer mechanism operates. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 799–803, 1998     

Intramolecular excimer formation in polymers: Pyrene Labelled Polyvinylacetate

The rate constant for intramolecular excimer formation between pyrenyl side-groups, in a polyvinylacetate chain at a mean separation of 200 bonds, has been measured as a function of molecular weight, solvent viscosity and solvent thermodynamic power. Above M = 1 × 10⁵, the rate constant is 1.4 × 10⁷ sec^?1 in low viscosity bad solvents. This value is about twenty times that for the rate constant of the analogous reaction between the two terminal groups in a chain with a mean end-to-end separation of 200 bonds. Increases of the viscosity and of the thermodynamic power of the solvent depress the rate constant, in agreement with the behaviour expected for a diffusion controlled reaction.     

Rate coefficients for the reaction of the acetyl radical,CH3CO,with Cl2 between 253 and 384 K

Rate coefficients, k, for the gas‐phase reaction CH₃CO + Cl₂ → products (2) were measured between 253 and 384 K at 55–200 Torr (He). Rate coefficients were measured under pseudo‐first‐order conditions in CH₃CO with CH₃CO produced by the 248‐nm pulsed‐laser photolysis of acetone, CH₃C(O)CH₃, or 2,3‐butadione, CH₃C(O)C(O)CH₃. The loss of CH₃CO was monitored by cavity ring‐down spectroscopy (CRDS) at 532 nm. Rate coefficients were determined by first‐order kinetic analysis of the CH₃CO temporal profiles for [Cl₂] < 1 × 10¹⁴ molecule cm^?3 and the analysis of the CRDS profiles by the simultaneous kinetics and ring‐down method for experiments performed with [Cl₂] > 1 × 10¹⁴ molecule cm^?3. k₂(T) was found to be independent of pressure, with k₂(296 K) = (3.0 ± 0.5) × 10^?11 cm³ molecule^?1 s^?1. k₂(T) showed a weak negative temperature dependence that is well reproduced by the Arrhenius expression k₂(T) = (2.2 ± 0.8) × 10^?11 exp[(85 ± 120)/T] cm³ molecule^?1 s^?1. The quoted uncertainties in k₂(T) are at the 2σ level (95% confidence interval) and include estimated systematic errors. A comparison of the present work with previously reported rate coefficients for the CH₃CO + Cl₂ reaction is presented. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 543–553, 2009     

Chemie polyfunktioneller Moleküle. 118 [1]. Synthesen und Kristallstrukturanalysen von bicyclischen Metallaphosphazenen des Platins und Eisens mit vier- und sechsgliedrigen Ringen

Chemistry of Polyfunctional Molecules. 118. Syntheses and Crystal Structures of Bicyclic Metallaphosphazenes with Four and Six Membered Rings Anhydrous MCl₂ (M = Pt, Fe) react with LiN(PPh₂)₂ ( 1 ) in the molar ratio of 1:2 in boiling toluene within 25 hours under partially oxidative scrambling of the PNP chain in 1 yielding the bicyclic metallaphosphazenes 5 a, b . While compound 5 a can be isolated in substance, the intermediate 5 b proves to be highly reactive but can be stabilized in the presence of CO, forming the 18-valence-electron coordination compound as an isomeric trans( 6 a )/cis( 6 b ) mixture in the molar ratio of 99:1. Also treatment of anhydrous PtCl₄ with four equivalents of 1 in boiling toluene during 60 hours yields 5 a . Alkylation of 5 a with CH₃I leads to the formation of the ionic species [Pt²⁺{Ph₂P? N(CH₃)? PPh₂}(Ph₂P? N = PPh₂ = N? PPh₂^?)]I^? ( 9 ). The X-ray crystal structures of 5 a × 1 CH₂Cl₂ and 6 a reveal, that the metal centres have a planar P-coordination polyhedron in the solid state. In the complex 9 × 2,5 CH₂Cl₂ however the torsion angle between the P? Pt? P planes of the four and six membered rings shows to be 15°. The six membered metallacycles in 5 a × 1 CH₂Cl₂, 6 a and 9 × 2,5 CH₂Cl₂ differ in their geometrical arrangement. All the new compounds have also been characterized by their ¹H, ³¹P{¹H}, ¹³C{¹H} NMR, IR, Raman and mass spectra.     

Tetrakis(μ‐benzothiazole‐2‐thiolato)‐1:2κ4N:S2;1:2κ4S2:N‐dichloro‐1κCl,2κCl‐dirhenium(III)(Re—Re) dichloromethane solvate: a bridged complex with a long Re—Re quadruple bond

The title compound, [Re₂(C₇H₄NS₂)₄Cl₂]·CH₂Cl₂, consists of dirhenium mol­ecules with bridging N,S‐benzo­thia­zole‐2‐thiol­ate ligands, axial Cl^? ligands and intramolecular hydrogen bonding. These mol­ecules adopt somewhat staggered conformations, with a long Re—Re quadruple bond distance of 2.2716 (3) Å.