表面活性剂CTMAB对阴极溶出伏安法测定硒的增敏作用的研究

硒(N)在pH 2. 09的Britton-Robinson缓冲溶液中,于一0. 59V (VS,SCE)处有一阴极溶出峰,当阳离子表面活性剂澳化十六烷基三甲钱(CTMAB)存在时,能使该阴极溶出峰峰高增高约l0倍.峰高与硒(N)浓度在2. 53 X 10-a ^-1. 52 X 10-' mol/L范围内呈线性关系,检出限为5.27X10-'mol/L(富集5min ).本文详细讨论了测定硒(N)的最佳条件及增敏机理,用该法测定了国家标准参考物质—海洋生物贻具、人发中的硒,结果令人满意.     

卡托普利在汞电极表面的电化学行为

用循环伏安法、阴极溶出伏安法和电毛细管曲线测量等方法研究了卡托普利在汞电极表面的电氧化机理。实验结果表明,酸性溶液中卡托普利比较稳定,而在中、碱性溶液中卡托普利不稳定。在酸性溶液中有质子参与电极过程,卡托普利在电极表面发生单电子转移,生成汞（Ｉ）－硫化合物,该化合物在电极表面有强吸附,并进一步转化成汞（Ⅱ）－硫化合物。按照实验结果,计算了卡托普利的扩散系数和电极反应速率常数,提出了卡托普利电化学氧     

Mǒsbauer study of the field induced uniaxial anisotropy in electro-deposited FeCo alloy films

Thin ferromagnetic films with in-plane magnetic anisotropy are promising materials for obtaining high microwave permeability.The paper reports a Mo¨ssbauer study of the field induced in-plane uniaxial anisotropy in electro-deposited FeCo alloy films.The FeCo alloy films were prepared by the electro-deposition method with and without an external magnetic field applied parallel to the film plane during deposition.Vibrating sample magnetometry and Mo¨ssbauer spectroscopy measurements at room temperature indicate that the film deposited in external field shows an in-plane uniaxial anisotropy with an easy direction coinciding with the external field direction and a hard direction perpendicular to the field direction,whereas the film deposited without external field does not show any in-plane anisotropy.Mo¨ssbauer spectra taken in three geometric arrangements show that the magnetic moments are almost constrained in the film plane for the film deposited with applied magnetic field.Also,the magnetic moments tend to align in the direction of the applied external magnetic field during deposition,indicating that the observed anisotropy should be attributed to directional ordering of atomic pairs.     

Determination of ultra trace amount of enrofloxacin by adsorptive cathodic stripping voltammetry using copper(II) as an intermediate

In this work, a simple and sensitive electroanalytical method was developed for the determination of enrofloxacin (ENRO) by adsorptive cathodic stripping voltammetry (ADSV) using Cu(II) as a suitable probe. The complex of copper(II) with ENRO was accumulated at the surface of a hanging mercury drop electrode at −0.10 V for 40 s. Then, the preconcentrated complex was reduced and the peak current was measured using square wave voltammetry (SWV). The optimization of experimental variables was conducted by experimental design and support vector machine (SVM) modeling. The model was used to find optimized values for the factors such as pH, Cu(II) concentration and accumulation potential. Under the optimized conditions, the peak current at −0.30 V is proportional to the concentration of ENRO over the range of 10.0-80.0 nmol L⁻¹ with a detection limit of 0.33 nmol L⁻¹. The influence of potential interfering substances on the determination of ENRO was examined. The method was successfully applied to determination of ENRO in plasma and pharmaceutical samples.     

Creatinine sensor based on a molecularly imprinted polymer-modified hanging mercury drop electrode

Molecularly imprinted polymers (MIP) have been elucidated to work as artificial receptors. In our present study, a MIP was applied as a molecular recognition element to a chemical sensor. We have constructed a creatinine sensor based on a MIP layer selective for creatinine and its differential pulse, cathodic stripping voltammetric detection (DPCSV) on a hanging mercury drop electrode (HMDE). The creatinine sensor was fabricated by the drop coating of dimethylformamide (DMF) solution of a creatinine-imprinted polymer onto the surface of HMDE. The modified-HMDE, preanodised in neutral medium at +0.4 V versus Ag/AgCl for 120 s, exhibited a marked enhancement in DPCSV current in comparison to the less anodised (≤+0.3 V) HMDE. The creatinine was preconcentrated and instantaneously oxidised in MIP layer giving DPCSV response in the concentration range of 0.0025-84.0 μg mL⁻¹ [detection limit (3σ) 1.49 ng mL⁻¹]. The sensor was found to be highly selective for creatinine without any response of interferents viz., NaCl, urea, creatine, glucose, phenylalanine, tyrosine, histidine and cytosine. The non-imprinted polymer-modified electrode did not show linear response to creatinine. The imprinting factor as high as 9.4 implies that the imprinted polymer exclusively acts as a recognition element of creatinine sensor. The proposed procedure can be used to determine creatinine in human blood serum without any preliminary treatment of the sample in an accurate, rapid and simple way.     

电解液流速对锌镍单液流电池性能的影响

通过电化学测试、 扫描电子显微镜观察和X射线衍射分析研究了电解液流速、 电流密度和锌沉积面容量三者关系及对锌镍单液流电池充放电性能和负极锌沉积形貌的影响. 结果表明, 锌沉积面容量是影响锌镍单液流电池充放电效率和负极锌沉积形貌的最主要因素, 电解液流速不宜过高或过低. 随着锌沉积面容量的增大, 电池的充放电效率和循环稳定性对电流密度的变化更为敏感, 适宜的电解液流速范围变窄. 锌沉积面容量在25 mA·h/cm²以上, 锌沉积皆呈海绵状. 在较低锌沉积面容量下, 电解液流速也较低时, 海绵锌沉积较为均匀致密. 而在高的锌沉积面容量下, 海绵状锌沉积的团簇和颗粒变大, 不均匀性加重, 仅在适中的电解液流速(7.1 L/min)下, 锌沉积部分致密规整, 电池具有较好的充放电性能.     

不同能级加速过滤电弧沉积四面体非晶碳膜的结构和性能

采用过滤阴极真空电弧技术，通过施加0—2000 V衬底负偏压使沉积离子获得不同能级的入射能量，在单晶硅上制备了四面体非晶碳薄膜.拉曼光谱分析表明，薄膜的结构为非晶sp³骨架中镶嵌着平面关联长度小于1 nm的sp²团簇.原子力显微镜研究表明：在低能级、富sp³能量窗口和次高能级，薄膜中sp³的含量越多，其表面就越光滑，应用sp³浅注入生长机制能够圆满地解释薄膜表面形态与离子入射能量之间的关系；但在高 关键词： 四面体非晶碳 过滤阴极真空电弧 能级     

椭偏法表征四面体非晶碳薄膜的化学键结构

采用自主研制的双弯曲磁过滤阴极真空电弧(FCVA)技术,在不同衬底负偏压下制备了四面体非晶碳(ta-C)薄膜。通过分光光度计和椭偏(SE)联用技术精确测量了薄膜厚度,重点采用椭偏法对不同偏压下制备的ta-C薄膜sp3 C键和sp2 C键结构进行了拟合表征,并与X射线光电子能谱(XPS)和拉曼光谱的实验结果相对比,分析了非晶碳结构的椭偏拟合新方法可靠性。结果表明,在-100V偏压时薄膜厚度最小,为33.9nm;随着偏压的增加,薄膜中的sp2 C含量增加,sp3 C含量减小,光学带隙下降。对比结果发现,椭偏法作为一种无损、简易、快速的表征方法,可用于ta-C薄膜中sp2 C键和sp3 C键含量的准确测定,且在采用玻璃碳代表纯sp2 C的光学常数及拟合波长选取250～1700nm时的椭偏拟合条件下,拟合数值最佳。     

Electrochemical Behavior of 6-Mercapto-Purine at Hanging Copper Amalgam Dropping Electrode and Its Trace Determination by Differential Pulse Adsorption Cathodic Stripping Voltammetry

Abstract

The electrochemical behavior of 6-MP was studied by cyclic voltammetry at a hanging copper amalgam dropping electrode (HCADE). It was found that 6-MP could form a complex with the Cu(II) stripped from the HCADE, showing a new peak at ?0.19V in the medium of 0.1mol/L LiClO₄-0.5mol/L HClO₄ solution. The mechanism of the reaction was proposed. This new peak was sensitive and could be used for the determination of trace 6-MP by differential pulse adsorption cathodic stripping voltammetry (DPAdCSV). The linear range was from 3.6×10^?10 to 5.3×10^?6 mol/L, and the detection limit was about 1.2×10^?10 mol/L (S/N=3). The method was also successfully applied to the determination of 6-MP in pharmaceutical tablets.     

Determination Of Nucleic Acid Bases At Nanomolar Concentrations By Means Of Cathodic Stripping Voltammetry

Abstract

It is shown that nucleic acid bases and some of their derivatives can be determined by means of cathodic stripping voltammetry (CSV). The limit of detection of adenine is about 2 × 10^?9 M. Presence of an excess of DNA does not interfere with the determination of free bases. CSV may be used also for the determination of nucleosides and nucleotides derived from purine bases.