铜膜差分脉冲阳极溶出伏安法测定药物中铋的含量

研究了铜膜电极代替汞膜电极测定重金属铋的差分脉冲溶出伏安法。实验了同位镀膜法测定铋的条件。在最佳实验条件下,Bi3+浓度在5×10-8~2×10-5mol/L范围内,其溶出峰峰高与浓度呈线性关系,检出限达到1×10-8mol/L。测定了一些药物中铋的含量,结果准确。     

二氧化碳和氧气的快速电化学方法联合测定

根据Ｏ２和ＣＯ２在二甲亚砜（ＤＭＳＯ）介质中Ｐｔ电极上的伏安特性，采用微电极并结构计算机控制的电位调制技术，建立了快速联合测定ＣＯ２和Ｏ２的调制电位脉冲库仑法和调制电位脉冲电流法，取得了满意的结果。一次测量时间快达４０ｍｓ。ＣＯ２检测范围０￣１０％（体积百分比）；Ｏ２检测范围不受限制。通过编程设计特定的调制电位－时间波形，可保持连续检测的长期稳定性。     

Voltammetric behaviour of bromhexine and its determination in pharmaceuticals

A complete electrochemical study and a novel electroanalytical procedure for bromhexine quantitation are described. Bromhexine in methanol/0.1 mol L⁻¹ Britton–Robinson buffer solution (2.5/97.5) shows an anodic response on glassy carbon electrode between pH 2 and 7.5. By DPV and CV, both peak potential and current peak values were pH-dependent in all the pH range studied. A break at pH 5.5 in E_P versus pH plot revealing a protonation–deprotonation (pK_a) equilibrium of bromhexine was observed. Spectrophotometrically, an apparent pK_a value of 4.3 was also determined.

An electrodic mechanism involving the oxidation of bromhexine via two-electrons and two-protons was proposed. Controlled potential electrolysis followed by HPLC–UV and GC–MS permitted the identification of three oxidation products: N-methylcyclohexanamine, 2-amino-3,5-dibromobenzaldehyde and 2,4,8,10-tetrabromo dibenzo[b,f][1,5] diazocine.

DPV at pH 2 was selected as optimal pH for analytical purposes. Repeatability, reproducibility and selectivity parameters were adequate to quantify bromhexine in pharmaceutical forms. The recovery was 94.50 ± 2.03% and the detection and quantitation limits were 1.4 × 10⁻⁵ and 1.6 × 10⁻⁵ mol L⁻¹, respectively. Furthermore, the DPV method was applied successfully to individual tablet assay in order to verify the uniformity content of bromhexine. No special treatment of sample were required due to excipients do not interfered with the analytical signal. Finally the method was not time-consuming and less expensive than the HPLC one.     

Synthesis and characterisation of bis(pentafluorophenyl)antimony(V) cations, [(C6F5)2SbL3]

Pentacoordinate complex cations of the general formula [(C₆F₅)₂SbL₃]³⁺ stabilized as solid salts in combination with tetraphenylborate (BPh₄), tetrafluorobroate (BF₄) anions, where L=DMSO, Ph₃AsO, PyO, DMF, α-, β- and γ-picoline have been isolated. The newly formed complexes were characterized by elemental analysis, molar conductance measurements, solid-state IR and and NMR. From these results, a five-fold coordination around antimony was required.     

Direct and simultaneous voltammetric analysis of heavy metals in tap water samples at Assiut city: an approach to improve the analysis time for nickel and cobalt determination at mercury film electrode

Tap water samples (Assiut city, lie in the middle north of upper Egypt, approx. 370 km from Cairo, January-March, 2002) were taken from the eight sampling sites of different locations at Assiut city. The samples are analyzed to determine the total content of cadmium, copper, lead and zinc by differential pulse anodic stripping voltammetry (DPASV) while nickel and cobalt are determined by a new simple differential pulse adsorptive stripping voltammetry (DPAdSV), using dimethylglyoxime (DMG) as the complexing agent. This method uses sodium sulfite as the supporting electrolyte, which facilitates the removal of oxygen interference without the traditional necessity of purging with inert gas. The effect of various parameters was studied using DPASV (for Cd, Pb, Cu and Zn) and AdSV (for Ni and Co) methods. Subsequently, under the so found experimental conditions, the stability of calibration curves and the detection limits (μg/l) have been determined. The data achieved (for all metals utility) are comparable to those measured by the graphite furnace atomic absorption spectrophotometric (GF-AAS) method. The effects of the interferences between these metal ions have been investigated. Moreover, the effect of storage was discussed and the obtained results were compared favorably with standard official methods. Statistical analysis of the database exhibits applicability and the accuracy of the techniques. The results obtained from the two techniques (Voltammetry and GF-AAS) are in very good agreements in the most tap water samples.     

Resolution of global signals using ratio differential pulse polarograms: Determination of p-nitroaniline and p-nitrotoluene in their mixture

Ratio differential pulse polarograms obtained by dividing the multianalyte and single analyte signals are proposed as a tool for resolution of global signals and quantification of the analytes from a qualitatively known mixture by differential pulse polarography (DPP) and related electroanalytical techniques. The influences of shape and position of the resolving function (DP polarograms of individual analyte) on the efficiency of resolution are discussed on simulated and experimental results. The method is applied for the determination of p-nitroaniline (NA) and p-nitrotoluene (NT) from their mixture in N,N′-dimethylformamide solutions with 0.1 M tetrabutylammonium iodide as supporting electrolyte, using an external calibration diagram and internal standard addition methods. NA and NT give one-electron DP polarographic peaks with 93 mV of peak separation and, therefore, show significant overlapping which depends on the concentration ratio of NA and NT in the mixture. The method is especially suitable for quantification of one analyte in the presence of a large excess of another analyte, because by division the component in excess is removed and the pseudo-ratio DPP of the minor component is clearly revealed in a way which is not possible by deconvolution using polynomial division or deconvolution by Fourier transforms.     

Decomposition of vegetables for determination of Zn,Cd, Pb and Cu by stripping voltammetry

A simple and accurate digestion method using nitric acid, perchloric acid and hydrogen peroxide has been developed for use in trace analysis for heavy metals in vegetables by differential pulse anodic stripping voltammetry. The recovery of the metals from the samples is lower if the hydrogen peroxide is omitted from the digestion mixture. Standard reference materials have been analysed satisfactorily by this method.     

新的脉冲进样AAS法测定“麻杏石甘汤”中的微量金属元素

本文研制了一种新的脉冲进样装置，用于火娄原子吸收分光光度法测定中药煎剂中的Ｃａ，Ｍｇ，Ｆｅ，Ｍｎ，Ｚｎ五种金属元素含量，实验表明，利用此种装置可以同时获得两种进样方式的分析结果，线性范围比常规法宽两倍，耗样量，精密度及分析速度均优于常规法。     

有机锗(锗-132)的示差脉冲极谱研究

用示差脉冲极谱法,在pH1.30H_2SO_4和3,4-二羟基苯甲醛(DHB)底液中,获得了有机锗(Ge-132)和无机锗Ge(Ⅳ)二个配位吸附极谱波,波峰分别为E_P2-0.62V和E_pl=-0.47V(υs.AgCI/Ag),Ge-132浓度在2.6×10_(-5)～3.1×10_（-3）mol/L范围内,Ge(Ⅳ)浓度在 3.1×10_（-5）～2.1×10_（-4）mol/L范围内分别与峰电流星线性关系.利用该示差脉冲极谱法可同时测定Ge-132和Ge(Ⅳ),用于有机锗营养口服液中Ge-132和Ge(Ⅳ)的测定结果满意.还探讨了Ge-132极谱波的性质,测定了有关动力学参数.     

Fast electron transfer repair of oxidizing OH adduct of dGMP by chlorogenic acid

ＥｘｔｅｎｓｉｖｅｓｔｕｄｉｅｓｏｆｒａｄｉａｔｉｏｎｏｒｃｈｅｍｉｃａｌｉｎｊｕｒｙｏｆｂｉｏｌｏｇｉｃａｌｔａｒｇｅｔｍｏｌｅｃｕｌｅｓｄｅｍｏｎｓｔｒａｔｅｔｈａｔＯＨｒａｄｉｃａｌ,ｔｈｅｍｏｓｔｒｅａｃｔｉｖｅｏｘｙｇｅｎｓｐｅｃｉｅｓ,ｒｅａｃｔｓｗｉｔｈｂｉｏｌｏｇｉｃａｌｍａｃｒｏｍｏｌｅｃｕｌｅｓ,ｓｕｃｈａｓＤＮＡ,ｉｎｄｕｃｉｎｇｂａｓｅａｌｔｅｒａｔｉｏｎｓ,ｂａｓｉｃｓｉｔｅｓ,ａｎｄｓｔｒａｎｄｂｒｅａｋｓ,ｒｅｓｕｌｔｅｄｉｎｖａｒｉｏｕｓｐａｔｈｏｇｅｎｅｓｉｓ,ｓｕｃｈ…