钴/玻碳离子注入修饰电极伏安法测定呋喃妥因的研究

呋喃妥因 (NFT)在 0 .1mol/LHAc NaAc (pH 4 .0 )溶液中于钴 /玻碳 (Co/GC)离子注入修饰电极上产生一灵敏的伏安还原峰 ,峰电位为 - 0 .2 6V(vs.Ag/AgCl) ,峰电流与NFT浓度在 6 .0× 10 -8～ 5 .0× 10 -6mol/L范围内呈线性关系 (r =0 .9987) ,检出限为 1.0× 10 -8mol/L。用线性扫描伏安法和循环伏安法研究了NFT的伏安行为、吸附特性和电极反应机理。测定了电子转移数 (n =4 )、转移系数 (α =0 .5 8)和参与反应的质子数 (X =4 )等电化学参数。结果表明该电极过程为一具有吸附性的不可逆过程。该法用于片剂中NFT含量的测定 ,得到满意的结果。用标准加入法测得该法的回收率为 94 .0 %～ 98.5 %。     

Performances of Aluminum-cobalt Co-substituted α-Ni(OH)2 Electrodes

Aluminum-cobalt co-substituted α-Ni(OH)2 was prepared by means of the titration method in a buffer solution, the structure was characterized by XRD analysis. With above mentioned α-Ni(OH)2 as the positive electrode of a nickel-metal hydride cell, the discharge performances were examined by constant-current charge-discharge experiments. In comparison with the electrodes made of aluminum substituted or cobalt substituted Ni(OH)2 materials, the aluminum-cobalt co-substituted composite electrodes possess an excellent electrochemical performance and are of practical significance.     

新试剂4-(2-吡啶偶氮)-邻苯三酚的合成及其与钴(Ⅱ)的显色反应

报道了水溶性新显色剂4 (2 吡啶偶氮) 邻苯三酚(PAPG)的合成。在溴化十六烷基三甲基铵(CTMAB)存在下的碱性介质中,试剂与Co(Ⅱ)形成稳定的蓝紫色配合物,其最大吸收波长(λmax)625nm,对比度(Δλ)171nm,表观摩尔吸光系数(ε625)1.47×104L·mol-1·cm-1。钴的质量浓度在0～0.72mg L范围内服从比耳定律。已用于维生素B12中钴的测定。     

显色剂1-(2-苯并噻唑)-3-(5,7-二溴-8-喹啉)-三氮烯的合成及与钴的显色反应

合成了新显色剂 1- (2 -苯并噻唑 ) - 3- (5 ,7-二溴 - 8-喹啉 ) -三氮烯 (BTDBQT) ,并研究了在阳离子表面活性剂存在下与钴的显色反应。在 p H9.5— 10 .5的硼酸盐缓冲介质中 ,钴与该试剂形成 1∶ 2的蓝色铬合物 ,其最大吸收波长在 6 42 nm处 ,表观摩尔吸光系数为 1.0 5× 10 5L· mol-1·cm-1,钴 ( )的浓度在0— 2 4 0 μg/ L范围内符合比耳定律。显色反应具有良好的选择性 ,常见离子除铜、镍外 ,基本不干扰测定。已应用于维生素 B12 和水系沉积物中微量钴的测定     

Single crystal studies on Co-containing τ-borides Co23−xMxB6 (M=Al, Ga, Sn, Ti, V, Ir) and the boron-rich τ-boride Co12.3Ir8.9B10.5

Single crystals of the cubic τ-Borides Co_23-xM_xB₆ (M=Al, Ga, Sn) were synthesised from the elements at temperatures between 1200 and 1500 °C. According to the structure refinements one (Ga, Sn: 8c) or two (Al: 4a and 8c) of the four independent metal sites show a mixed occupation Co/M resulting in the compositions Co_20.9Al_2.1B₆, Co_21.9Ga_1.1B₆, and Co_21.4Sn_1.6B₆, respectively. Melts with Indium gave access to Co₂₃B₆ as the first binary τ-boride (a=10.4618(13) Å, 104 refl., 14 param., R₁(F)=0.0132, wR₂(F²)=0.0210). With M=Ir mixed occupations occur for all sites and the boron content varies. The composition for the boron-poor single crystal was Co_16.2Ir_6.8B₆. A higher Ir-content enables the uptake of additional boron resulting in a composition Co_12.3Ir_8.9B_10.5. This can be explained be the substitution of metal atoms on the 8c-site by B₄-tetrahedra. A boron-rich phase was observed for the first time for a τ-boride of cobalt. All compositions were confirmed by EDX measurements.     

A procedure for determination of cobalt in water samples after dispersive liquid–liquid microextraction

In this work, a procedure for preconcentration of cobalt using dispersive liquid–liquid microextraction (DLLME) with the reagent Br-TAO as complexing reagent was developed. The procedure is based on a ternary system of solvents, where appropriate amounts of the extraction solvent, disperser solvent and the chelating agent Br-TAO are directly injected into an aqueous solution containing Co(II). A cloudy mixture is formed and the ions are extracted in the fine droplets of the extraction solvent. After extraction, the phase separation is performed with a rapid centrifugation, and cobalt is determined in the enriched phase by FAAS. Under the optimized conditions, the detection limit obtained was 0.9 µg L^{− 1}. The enrichment factor and the consumptive index were 16 and 0.31 mL, respectively. The accuracy of the method was tested by the determination of cobalt in certified reference material of spinach leaves, NIST 1570a. The proposed procedure was successfully applied to the determination of cobalt in water samples.     

Cobalt Sulfate as a Recyclable Catalyst for Chemoselective Synthesis of Diacetates from Aldehydes

A mild and efficient method for diacetylation reaction was developed,by which diacetate could be achieved through the reaction of aldehyde with acetic anhydride,in the presence of cobalt sulfate,with an admirable yield,at room temperature,without solvent.The catalyst could be recycled six times without a distinct loss of activity.     

A microband lactate biosensor fabricated using a water-based screen-printed carbon ink

The present study demonstrated for the first time that screen-printed carbon microband electrodes fabricated from water-based ink can readily detect H₂O₂ and that the same ink, with the addition of lactate oxidase, can be used to construct microband biosensors to measure lactate. These microband devices were fabricated by a simple cutting procedure using conventional sized screen-printed carbon electrodes (SPCEs) containing the electrocatalyst cobalt phthalocyanine (CoPC). These devices were characterised with H₂O₂ using several electrochemical techniques. Cyclic voltammograms were found to be sigmoidal; a current density value of 4.2 mA cm⁻² was obtained. A scan rate study revealed that the mass transport mechanism was a mixture of radial and planar diffusion. However, a further amperometric study under quiescent and hydrodynamic conditions indicated that radial diffusion predominated. A chronoamperometric study indicated that steady-state currents were obtained with these devices for a variety of H₂O₂ concentrations and that the currents were proportional to the analyte concentration. Lactate microband biosensors were then fabricated by incorporating lactate oxidase into the water-based formulation prior to printing and then cutting as described. Voltammograms demonstrated that lactate oxidase did not compromise the integrity of the electrode for H₂O₂ detection. A potential of +400 mV was selected for a calibration study, which showed that lactate could be measured over a dynamic range of 1-10 mM which was linear up to 6 mM; a calculated lower limit of detection of 289 μM was ascertained. This study provides a platform for monitoring cell metabolism in-vitro by measuring lactate electrochemically via a microband biosensor.     

A New Transition Metal Tetracyanidoborate: Synthesis,Structure and Properties of Co[B(CN)4]2·2H2O

The reaction of tetracyanidoboronic acid, H[B(CN)₄], with CoCO₃ or Co(OH)₂ in aqueous solution leads after slow evaporation of water to single crystals of Co[B(CN)₄]₂ · 2H₂O. The compound has been characterized by single crystal X‐ray diffraction ( , a = 12.2922(9), c = 9.2235(7) Å, Z = 4). The Co²⁺ ion is octahedrally coordinated by four nitrogen atoms of four different tetracyanidoborate CN groups occupying the four equatorial positions and two molecules of water occupying the remaining corners of the octahedron. The single crystal X‐ray structure, the vibrational spectra, and the thermal properties are compared with other known tetracyanidoborates with divalent cations.     

Synthesis and X‐ray Crystal Structure of Bis[oxamide dioximato‐κ2N,N′](oxamide dioxime‐κ2N,N′)cobalt(III) Perchlorate Hexahydrate

Co(OAc)₂ reacts with oxamide dioxime (H₂oxado) in water in the presence of ClO₄^– ions to produce [Co(Hoxado)₂(H₂oxado)]ClO₄ · 6H₂O ( 1 ), where Hoxado^– is the anion of H₂oxado, derived from the deprotonation of one of the two hydroximinic groups, and in which oxidation of Co^II to Co^III (in air) had occurred. 1 is the first example of a salt in which the cation, [Co(H₂oxado)₃]³⁺, is doubly deprotonated to generate the chiral cation, [Co(Hoxado)₂(H₂oxado)]⁺. The central cobalt cation is pseudo‐octahedrally coordinated by six nitrogen atoms. In the solid state, the complex cations form centro‐symmetric dimers via O–H ··· O bridges. The bulk structure is consolidated by an extended three‐dimensional network of O–H ··· O and N–H ··· O bridges that interconnect the ionic constituents and the water molecules.