开设综合化学实验的探索与实践

1　开设综合化学实验的必要性　　化学是 1门实验科学 ,实验课在化学教学中占有特殊的地位。传统的教学模式中 ,化学系的学生在低年级做各基础课实验 ,高年级做专门化实验和毕业论文。各基础课具有自身的基础理论、实验操作技能 ,学生在这些实验课中是分别学习的 ,各门课的知识和技能也是分别学习和掌握的 ,学生缺乏大量有关知识和技能的融会贯通 ,缺乏各种实验方法和技术的综合应用能力 ;而高年级的专门化实验又由于专业划分过细 ,知识分割过窄 ,使学生学得的知识过窄 ,实验方法和技能也较单一 ,尽管基础扎实 ,但缺少创新意识和能力。所以 …     

铬天青S的极谱

本文用极谱法和循环伏安法研究了铬天青S和电还原。在Britton-Robinson缓冲溶液中,在PH4-11时,铬天青S可产生两个受扩散控制的一电子还原波。其中第一波(峰)相当于由氧化态还原为中间态;第二波(峰)相当于由中间态不可逆地还原为还原态。根据实验结果提出了电还原机理。     

Dynamic coating for resolving rhodamine B adsorption to poly(dimethylsiloxane)/glass hybrid chip with laser-induced fluorescence detection

In this paper a method was described about dynamic coating for resolving rhodamine B (RB) adsorption on a hybrid poly(dimethylsiloxane) (PDMS)/glass chip. The results showed that when the non-ionic surfactant Triton X-100 was higher than 0.5% (v/v) into the phosphate buffer, the adsorption of RB appeared. Besides, some separation conditions for RB were investigated, including concentration of Triton X-100, concentration and pH value of running buffer, separation voltage and detection site. Through comparing electroosmotic flow, plate numbers and other parameters, an acceptable separation condition was obtained. Under optimized conditions, the precisions of RB detection (R.S.D., n = 10) were 2.62% for migration time, 4.78% for peak height respectively. Additionally, RB concentration linearity response was excellent with 0.9996 of correlation coefficient between 1 and 100 μM, and a limit of detection (S/N = 3) was 0.2 μM. Finally, we separated rhodamine B isothiocyanate and lysine deriving from the fluorescent probe, and the result displayed that the dynamic coating method was applicable by CE separations using PDMS/glass chip.     

Multielemental NAA of geological micro-grain samples for origin identification

Thirty two elements were determined in five pieces of presumed cosmic dust samples with the weights of 5 to 25 g by neutron activation analysis (NAA). All the interferences from fission, threshold reactions and -spectra were corrected for and different counting geometries normalized. Enrichment factors with reference to C1-chondrite are about 200 and 100 for lithophile refractory elements (e.g., V, Th, Hf and W) and rare earth elements (REE), respectively. Deficiencies were observed for Co, Cr, Mg and Na, etc. The C1-chondrite normalized REE patterns are close to those of extraterrestrial materials, with no anomaly of Eu, indicating an extraterrestrial origin of the grain samples analyzed.     

巯基化合物在铁氰化铟薄膜修饰玻碳电极上的电催化氧化及其液相色谱安培测定

在酸性介质中，铁氰化铟薄膜修饰玻碳电极（ＩｎＨＣＦ／ＧＣ）大大催化了巯基化合物的氧化。比较了不同制备方法所得修饰电极的稳定性。全氟代磺酸Ｎａｆｉｏｎ涂敷于修饰电极表面增强了其在流动体系中的稳定性。液相色谱分离检测了半胱氨酸、还原型谷胱甘肽和Ｎ－乙酰半胱氨酸。线性范围达２个数量级。检测限为１．７ｎｇ、１０．０ｎｇ和６．０ｎｇ。     

2,2′联吡啶在水/硝基苯界面对Co(Ⅱ)的相转移催化

循环伏安法研究表明2,2′-联吡啶催化Co(Ⅱ)通过水/硝基苯界面的相转移伴有化学反应发生。水相或有机相的伴随化学反应直接影响Co(Ⅱ)与2,2′-联吡啶逐级配合物的相转移的循环伏安行为,并观察到类似于金属电极/电解质溶液界面出现的不可逆渡,不同的配合物,相转移机制不同。     

Controlled rearrangement of adsorbed undecanol films on mica surfaces induced by an atomic force microscopy tip

An undecanol film adsorbed on a mica surface was found to rearrange and spread in a position-controlled way induced by a tapping mode atomic force microscopy (AFM) probe. AFM images of varying scanning times showed that before forming an ordered monolayer the undecanol molecules were adsorbed on the mica surface in the disordered and disorganized status. With the proceeding of scanning, these undecanol molecules gradually formed an ordered and flat film. Such behavior was caused by the formation of a stable film and had never been reported for other alcohols.     

Direct detection of acetaminophen in urine by liquid chromatography with electrochemical detection using dual electrodes. Preliminary application to a single-dose pharmacokinetic study

A method for the direct determination of acetaminophen in urine based on liquid chromatography with series dual-electrode detection has been developed. No sample pretreatment steps are required except for filtration. The method gives a linear range from 0.5 to 300 μg ml^?1 and a detection limit of 0.2 μg ml^?1 (10 μl). The analysis time of the assay is less than 7 min. The pharmacokinetics of acetaminophen in urine from a subject who had orally ingested 450 mg (table form) of the drug were studied and various pharmacokinetic parameters were determined.