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101.
应用电位滴定法测量了烷基巯基四氮茚等一系列感光乳剂稳定剂的银盐溶度积和酸离解常数,其中有些化合物的常数属首次报道;所得数据表明:含巯基的四氮茚的银盐溶解度小于4-羟基-1,3,3a,7-四氮茚类化合物.同时应用Harmmett方程考察了感光乳剂稳定剂或防灰雾剂的性质,结果表明:从苯衍生物导出的σ值也可应用于预测杂环化合物的某些特性. 相似文献
102.
高灵敏示波电位动力学分析法测定茶单宁 总被引:5,自引:0,他引:5
本文利用KBrO3和KBr的氧化还原反应与茶单宁的溴代反应间的速度差异,将动力学分析法与示波电位法结合起来,提出了测定痕量茶单宁的新方法。在0.032mol/LHCl介质中,KBrO3和KBr浓度为0.0005和0.001mol/L时,方法的检出限为3.8μg/L,相对标准偏差为2.8%。调整上述试剂浓度,可使测定范围延伸几个数量级(从ng级到mg级)。该方法灵敏、简便、快速,且不受颜色等干扰。用于饮料、体液和茶树样品中茶单宁的测定,结果与酒石酸铁比色法相差—7.9%~5.5%。 相似文献
103.
104.
105.
活化高分子膜免疫电极检测乳腺癌抗原 总被引:4,自引:0,他引:4
报道了一种灵敏度高和使用简便的免疫电极,用于测定乳腺癌抗原(CA15-3)。CA15-3抗体固定在用羟胺活化的聚氯乙烯(PVC)-牛血清白蛋白(BSA)基体膜上。当抗体膜与CA15-3血清结合形成抗原体复合物膜后,将该复合物膜固定在自制Ag-AgCI基体电极顶端,利用毫伏计测定膜电位。该法可在15-240U/mL范围测定CA15-3,线性关系良好,回归方程:△E=-8、84 13、97Ig[CA15-3],相关系数0.9998。人血清中其他常见抗原对CA15-3测定基本无干扰。同时,探讨了免疫膜的电位响应机理。 相似文献
106.
Construction of a Triphenyltetrazolium Liquid Membrane Ion Selective Electrode and its Analytical Application to the Assay of Vitamin C 总被引:2,自引:0,他引:2
Panayotis G. Veltsistas Theodosios I. Sikalos Mamas I. Prodromidis Christos D. Papadimitriou Miltiades I. Karayannis 《Mikrochimica acta》2000,135(1-2):113-117
The construction of a liquid triphenyltetrazolium cation (TT+) ion-selective electrode (ISE) based on [TT+]3[P(W3O10)4] salt dissolved in 2-nitrotoluene is described. The liquid membrane electrode exhibits a rapid and almost Nernstian response
to triphenyltetrazolium cations in the concentration range from 2×10−4 to 1×10−2 mol l−1. The Nernstian slope is 56–58 mV decade−1 which remains constant for at least two months. The response is virtually unaffected by pH changes in the range 3–12. Major
interferents are periodate and malate. Deviation from linearity is also observed in the presence of bromide, iodide and thiocyanate,
due to their precipitation with triphenyltetrazolium cations. Analytical applications such as direct potentiometry for the
determination of TT+ in aqueous solutions and indirect potentiometry for the assay of ascorbic acid (vitamin C) in pharmaceutical preparations
are described. Ascorbic acid in the range of 150–500 mg l−1, under specified experimental conditions, can be determined with mean relative error of 1.9%.
Received February 25, 2000. Revision April 4, 2000. 相似文献
107.
《Analytical letters》2012,45(6):1081-1095
Abstract A simple potentiometric method is described for mercurimetric titration of barbiturates using a solid-state iodide ion-selective electrode. The optimum titration conditions involve the use of a borate buffer of pH 9–10 as a medium and mercury(II) perchlorate of pH 1.7–1.9 as a titrant. Under these conditions, titration curves with two sharp consecutive inflection breaks are obtained. The first inflection corresponds to quantitative and stoichiometric reaction of barbiturates with mercury(II) and the second break is due to the reaction of the buffer with the titrant. No interferences are caused by Cl?, Br?, PO4 3- and many excipients and diluents commonly used in the drug formulations. Determination of barbiturates in various pharmaceutical preparations gives reproducible results with an average recovery of 99.1% of the nominal (st.dev. 0.3 %) and the method offers significant advantages over the titrimetric method of the British Pharmacopoeia. 相似文献
108.
Mohammad Reza Abedi Mohammad Reza Ganjali Parviz Norouzi 《International journal of environmental analytical chemistry》2013,93(5):353-362
2,5-Dioxo-4-imidazolidinyl was used as an excellent sensing material in the preparation of a PVC membrane for a Ce(III)-selective sensor. The electrode shows a good selectivity for the Ce(III) ion with respect to most common cations including alkali, alkaline earth, transition, and heavy metal ions. The developed sensor exhibits a wide linear response with a slope of 19.6?±?0.3 mV per decade over the concentration range of 1.0?×?10?6 to 1.0?×?10?1 M, while the illustrated detection limit is 5.7?×?10?7 M of Ce(III) ions. Moreover, it is concluded that the sensor response is pH-independent in the range of 3.1–9.8. The applications of the recommended electrode include the determination of concentration of Ce(III) ions in soil and sediment samples, validation with CRM's, and the Ce(III) ion potentiometric titration with EDTA as an indicator electrode. 相似文献
109.
The determination of peroxidase activities is the basis for enzyme‐labeled bioaffinity assays, peroxidase‐mimicking DNAzymes‐ and nanoparticles‐based assays, and characterization of the catalytic functions of peroxidase mimetics. Here, a facile, sensitive, and cost‐effective solvent polymeric membrane‐based peroxidase detection platform is described that utilizes reaction intermediates with different pKa values from those of substrates and final products. Several key but long‐debated intermediates in the peroxidative oxidation of o‐phenylenediamine (o‐PD) have been identified and their charge states have been estimated. By using a solvent polymeric membrane functionalized by an appropriate substituted tetraphenylborate as a receptor, those cationic intermediates could be transferred into the membrane from the aqueous phase to induce a large cationic potential response. Thus, the potentiometric indication of the o‐PD oxidation catalyzed by peroxidase or its mimetics can be fulfilled. Horseradish peroxidase has been detected with a detection limit at least two orders of magnitude lower than those obtained by spectrophotometric techniques and traditional membrane‐based methods. As an example of peroxidase mimetics, G‐quadruplex DNAzymes were probed by the intermediate‐sensitive membrane and a label‐free thrombin detection protocol was developed based on the catalytic activity of the thrombin‐binding G‐quadruplex aptamer. 相似文献
110.
Aparna Sil & Ashwini K. Srivastava 《Supramolecular chemistry》2013,25(5):343-351
Complexation of Cu(II), Zn(II), Ni(II), Co(II), Pb(II), Cd(II), Cr(III) and Fe(III) ions with 15-crown-5, benzo-15-crown-5, 18-crown-6, dibenzo-18-crown-6, dicyclohexano-18-crown-6, dibenzo-24-crown-8, 5,6,14,15-dibenzo-1,4-dioxa-8,12-diazacyclopentadeca-5,14-diene, 1,4,10-trioxa-7,13-diazacyclopentadecane and cyclam has been investigated in 75% (v/v) DMF+water using the silver(I) ion as an auxiliary cation at 0.05?M ionic strength adjusted with tetrabutylammonium perchlorate (TBAP) by competitive potentiometry. Stability constant values obtained for the metal ion–aza macrocyclic complexes are higher than those for the oxa crowns. Shifts in the peak potential and reduction in the peak current in the differential pulse polarography (DPP) method were also used to determine the stability constants of some of the metal ions with aza and tosylated-aza macrocycles using TBAP as supporting electrolyte in 75% (v/v) DMF+water and 90% (v/v) DMSO+water media. Stability constant values determined both by shifts in the potential and by reduction in the peak current were found to be in good agreement with each other. 相似文献