高效液相色谱法测定卷烟烟气总粒相物中的烟碱

采用反相高效液相色谱内标法测定卷烟烟气总粒相物中的烟碱含量,内标物为对氨基苯碘酸,方法的平行回收率为９９．７％～１００．１％,精密度好,操作简便、快速,可作为检测烟碱的一种可靠方法。     

基体辅助激光解吸电离飞行时间质谱和热裂解色谱/质谱研究聚酯型聚氨酯链结构

聚酯型聚氨酯样品用基体辅助激光裂解离子化质谱(MALDI-TOF/MS)和热裂解色谱质谱(PYGC/MS)方法进行了鉴定,PYGV/MS方法可检出PU的一些组成单元的化学结构,但PYGC/MS中大多数的峰,无法从常规的标准化合物的质谱数据库中检索到,而MALDI-MS方法,可明确测出PU试样各种单元的组合、聚合度及PU长链的序列分布,质量数范围可达2300.     

可生物降解的冷冻机油

用CEC(欧洲协作委员会 )生物降解性试验方法研究了与R - 1 34a相匹配的冷冻机油———改性聚醚 (PAG)系列和多元醇酯 (POE)系列的生物降解规律 ,并经过适当的调配 ,使之不但满足于压缩机的运转要求 ,还符合环保要求     

纳米级β-磷酸钙的合成

通过Ca(OH)2/H3PO4/H2O体系合成了一系列的纳米级β-磷酸钙,研究了反应物浓度、反应时间对β-磷酸钙中Ca/P比的影响,应用IR,TEM,XRD对其形态和组成进行了表征并和Ca(NO3),4H2O/(NH4)2HPO4/H2O体系所制得的β-磷酸钙进行了比较.研究表明:两种方法都可以直接制备纳米级β-磷酸钙,烧结后晶体结构更完善.     

简单一级反应数据处理的一个新模型

利用产物和反应物某一物理性质的差别来测定反应速率、确定动力学参数是常用的方法.过氧化氢催化分解、蔗糖水解等典型的物理化学实验都是以物理性质代替浓度进行动力学测定,最后确定反应速率常数的.     

Trans-membrane electron transfer in red blood cells immobilized in a chitosan film on a glassy carbon electrode

We have studied the trans-membrane electron transfer in human red blood cells (RBCs) immobilized in a chitosan film on a glassy carbon electrode (GCE). Electron transfer results from the presence of hemoglobin (Hb) in the RBCs. The electron transfer rate (k _s) of Hb in RBCs is 0.42 s^?1, and <1.13 s^?1 for Hb directly immobilized in the chitosan film. Only Hb molecules in RBCs that are closest to the plasma membrane and the surface of the electrode can undergo electron transfer to the electrode. The immobilized RBCs displayed sensitive electrocatalytic response to oxygen and hydrogen peroxide. It is believed that this cellular biosensor is of potential significance in studies on the physiological status of RBCs based on observing their electron transfer on the modified electrode.

Adsorptive removal of La(III) from aqueous solutions with 8-hydroxyquinoline immobilized GMZ bentonite

Due to the low permeability, high swelling capacity and good retardation properties, bentonite has been considered as the main component of buffer/backfill material for high level radioactive wastes repository all over the world. The adsorptions of metal ion were widely investigated recently. In this presentation, we provide an easy-to-use method to immobilize 8-hydroxyquinoline onto the surface of bentonite for the use of adsorption studies of La(III) from the aqueous solution. The effects of various parameters such as contact time, pH of the solution, ionic strength and metal ion concentration on the adsorption were investigated by the batch experiments. The biggest adsorption capacity is 41.7 mg/g, higher than the value reported by our previous work which is performed by the raw bentonite. Langmuir isotherm fits the experimental data well and the adsorption follows pseudo-second-order kinetic model. In summary, 8-hydroxyquinoline immobilized GMZ bentonite is an effective adsorbent for the removal of La(III) from aqueous solutions.     

Colorimetric and visual determination of melamine by exploiting the conformational change of hemin G-quadruplex-DNAzyme

We report on the detection of trace quantities of melamine (MA) by a colorimetric method that exploits the conformational change of hemin G-quadruplex-DNAzyme. The addition of MA to hemin G-quadruplex-DNAzyme structure containing thymine bases causes the thymine in the DNAzyme to interact with MA via a stable triple H-bond and leads to a conformational change. This, in turn, affects the peroxidase-like activity of hemin which is determined colorimetrically at 450 nm by adding 3,3’,5,5’-tetramethylbenzidine and hydrogen peroxide. The method was applied to the colorimetric determination of MA over a wide range of concentrations (0.2 to 24 μM) with a detection limit of 80 nM. The effect also can be detected with bare eyes. The method was successfully applied to the determination of MA in spiked milk powder.

Crystal structures, magnetic, dielectric and ferroelectric properties of two copper(II) complexes with m-nitrobenzoic acid

Reactions of CuCl₂, m-nitrobenzoic acid (HNBA) and NaOH with 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) in aqueous ethanol afforded two Cu(II) complexes Cu(bpy)(NBA)₂, 1, and [Cu(phen)(H₂O)₂(NBA)](NBA), 2. The monomolecular Cu(bpy)(NBA)₂ moieties are both bridged by hydrogen bonding interactions and interlayer π ^*–π ^*stacking interactions to form a 3D (3,4,6)-connected supramolecular architecture with the Schäfli symbol of (4⁴·6²)(4⁴·6⁶·8⁵)(6³)₂. Complex 2 crystallizes in a noncentrosymmetric space group P2₁ where all molecules show the same orientation along the polar b axis. Preliminary investigations suggest that 2 exhibits ferroelectric hysteresis loops at room temperature with remanent polarization (P _r) of ca. 0.09 μC cm^?2 and coercive electric fields of 2.53 kV cm^?1, respectively. It may be a potential ferroelectric with a relatively large spontaneous polarization (P _s) of 0.22 μC cm^?2. Furthermore, permittivity property measurements reveal a dielectric constant (ε _r) of 6.36. Variable-temperature (2–300 K) magnetic susceptibility measurements showed the presence of weak ferromagnetic interactions between the Cu(II) ions for both 1 and 2.