甲基紫电极催化动力学电位法测定亚硝酸根

基于在稀磷酸介质中亚硝酸根对溴酸钾氧化甲基紫的反应具有明显的催化作用 ,应用自制的甲基紫选择性电极跟踪反应液中甲基紫浓度的变化 ,建立了一种测定亚硝酸根的催化电位新方法。该方法在室温下进行 ,操作方便 ,样品溶液不受颜色限制。在选择的最佳条件下 ,检出限为 7 6× 1 0 -7g/L ,线性范围为8 0× 1 0 -7～ 8.0× 1 0 -5g/L。用于肉制品中亚硝酸根含量的测定 ,结果满意     

催化动力学电位法测定微量锰的研究

用结晶紫选择性电极（自制）以催化电位法对测定微量锰进行了研究。该方法测定标的线性范围为７～７４μｇ／Ｌ，对标准钢样中的锰含量测定结果满意，且操作方便。     

孔雀绿电极催化电位滴定法测定中草药中的锰

以氨三乙酸存在下锰（Ⅱ）催化高碘酸钾氧化孔雀绿的反应作指示反应，用孔雀绿选择性电极作指示电极，对于用催化电位滴定法测定微量锰进行了研究，选择了适宜的实验条件，并测定了中草药中的锰的含量，所得结果与原子吸收法一致。     

罗丹明B电极催化电位法测定微量锰的研究

本文基于在邻二氮菲（活化剂）存在下，Ｍｎ（Ⅱ）对高碘酸根氧化罗丹明Ｂ退色反应的催化作用，对于用罗丹明Ｂ电极（自制）以催化电位法测定微量锰进行了研究。实验表明，该方法测锰的线范围为１１－４８ｎｇ／ｍｌ。选择性较好，温度控制方便。本文在未经分离的情况下测定了标准钢样品的锰含量，结果满意。     

氯离子选择性电极电位法测定光气含量

光气是医药、染料、农药等有机合成的重要原料,也是剧毒的气体。因此,对光气的分析测定也是十分重要。分析光气的方法颇多,诸如气相色谱法、高压液相色谱法、吸光光度法等。但用离子电极法国内外报道者甚少,曾查阅到日本专利报道过用玻璃电极法测光气,由于文献不全未进行验证。本文根据氯离子的电化学特性采用氯离子电极探讨了光气含量的氯离子选择性电极电位测定法。对光气合成或环境保护监测具有一定的实用和参考价值。     

铜的催化动力学电位法测定

本文报道了利用碘离子选择电极监测Ｈ２Ｏ２－ＫＩ氧化还原反应体系被Ｃｕ（Ⅱ）催化的反应速度，建立了测定Ｃｕ（Ⅱ）的催化动力学方法，其线性范围为１０－８０ｎｇ／ｍＬ，该法用于铝合金标样中铜的测定，结果非常接近标准样品的标准值，相对标准偏差为０．３６％，回收率在９８．３％－１０５．６％之间。     

离子选择性电极电位法测定钼矿石和钨矿石中氟

采用过氧化钠熔融钼矿石、钨矿石样品,乙二胺四乙酸钠和5-磺基水杨酸混合溶液浸取盐分,将样品溶液静置12h,吸取上层清液,以乙二胺四乙酸钠-硝酸钾组成的混合溶液作为总离子强度缓冲剂,控制溶液pH值为5.1,使用pF-1型氟离子选择电极,以饱和甘汞电极作参比电极测定溶液的平衡电位值。采用标准曲线法测定钼矿石和钨矿石中氟。钼矿石标准物质测定值的相对标准偏差(n=11)为3.36%,经4种国家一级钼矿石、钨矿石标准物质的分析验证,测定结果与标准值吻合。     

结晶紫选择电极的制备及催化电位法测定碘的研究

根据磷酸介质中碘离子催化高碘酸钠氧化结晶紫的氧化还原反应,应用自制的结晶紫选择电极跟踪紫的 度变化,对催化电位法测定碘进行了研究。测定碘离子 的线性范围为０．２０－５．５μｇ／２５ｍＬ,方法检出限为４．１＊１０＾－９ｇ／ｍＬ。该方法应用于测定食盐和饮用水中碘含量,ＲＳＤ〈４．１％,平均回收率为９５．１％。     

Determination of L-Ascorbic Acid by Adsorption Potentiometry with Carbon Paste Electrode

Abstract

This paper reports the potentiometric measurement of ascorbic acid in the solution of 0.10 mol/L NaOH-0.1 mol/L NaCl using carbon paste (the mixture of spectroscopic graphite powder and di-iso-octyl phthalate) electrode(room temperature 15°C), with the linear range 7.0 × 10^?7 × 4.0 × 10^?5mol/L, average response slope 95mV/decade and detection limit 1 × 10^?7mol/L. Phenol, sulfite, Mn²⁺ and so on pose no interference to the measurement of ascorbic acid. This method is characterized by fine selectivity, reproducibility and accuracy. The potential response behavior is caused chiefly by chemisorption of ascorbic acid to the surface of the carbon.

Each year yields a number of papers concerning the determination of ascorbic acid by various methods, including gas chromatographymass spectrometry¹, capillary electrophoresis², spectrophotometry³, voltammetry⁴, titrimetric method⁵, biosensor⁶ and so on, Each method has its merits and defects in analyzing different samples. M. Petersson⁷ worked out the potentiometric sensor for determining ascorbic acid by modifying monolayer of ferrocene upon the surface of half-oxidized platinum electrode with an average response slope 50±8.8mV/decade, but this sensor suffers from inadequate selectivity. In our study, carbon paste electrode (without ionophore) is applied in the determination of ascorbic acid by potentiometry with an average response slope 95mV/decade. This method displays fine selectivity, accuracy, convenience and rapidity of determination.     

The Determination of Sodium in Alumina Using a Sodium Selective Ion Electrode

Abstract

A method has been developed for the determination of sodium in alumina using a selective ion electrode. The alumina sample is dissolved in ammonium hydrogen fluoride in platinum crucibles or sintered with boric acid using either platinum, nickel, or zirconium crucibles. Either dissolution technique completely extracts all available sodium. After dissolution, and in the presence of citrate to prevent aluminum hydroxide precipitation, the pH is adjusted to 8.7 with ammonium hydroxide, and the sodium concentration is determined by a sodium selective ion electrode.     

催化动力学电位法测定痕量亚硝酸根

基于稀硫酸介质中，亚硝酸根对溴酸钾氧化碘化钾有催化作用，用碘离子选择电跟踪I^-，建立了测定痕量亚硝酸根的催化动力学电位法。在适宜条件下，该指示反应为一级反应，反应速度可用电位的变化（ΔE）表示。当时间固定时，ΔE与亚硝酸根浓度在0－0．12mg/L范围内呈线性关系，检出限为2．0μg/L。该法用于水样中痕量亚硝酸根的测定，结果满意。     

Lithium Ion Selective Electrode Based on Ionomycin Methyl Ester

Abstract

An ion-selective electrode based on ionomycin methyl ester, a derivative of the naturally occurring carboxylic polyether antibiotic ionomycin, is described which exhibits high Li⁺ selectivity. The selectivity coefficients of the electrode based on ionomycin methyl ester, log K^pot _LiNa and log K^pot _LiK are -1.3 and -1.9, respectively.     

Determination of Sulphur in Solid and Liquid Samples by Potentiometric Titration with Ion Selective Electrode.

Abstract

This paper describes a potentiometric method for the determination of sulphur in solid and liquid samples, using a sulphide ion selective electrode after the reduction distillation step. The determination of sulphide in solid and liquid samples without prior treatment was carried out by direct and titration potentiometric methods.

The reproducibility of the method and the recovery of sulphate in solid samples was investigated using analytical reagent grade 99% sodium sulphate. Portions of aproximately 100 mg of reagent were subjected to the reduction distillation process. After the ion selective electrode showed a stable value of the potential, indicating that all the sulphate had been reduced to sulphide, the potentiometric titration with lead nitrate solution was performed. A mean recovery of 98% of sulphate was found. The potentiometric titration method described in this work, can be applied to determine S⁼ in solid samples with the advantage that it does not require sample solubilization or extraction prior to the determination. The method yields an almost total reduction of sulphur and also a good precision.     

Determination of Total Fluoride in Oral Products by Using of Potentiometry With Ion Selective Electrode: A Critical Study

ABSTRACT

In this work, a critical study of the determination of fluoride in oral products with an ion selective electrode was performed. The influence of the type of fluorine compound in the sample as well as the practical factors involved in the analysis were investigated. Fluoride could be determined, directly, in samples where it is in the form of NaF or SnF₂. However, in samples where it is as MFP (sodium monofluorophosphate) an acid treatment was needed for removal of fluoride from the PO₄F^2? ion. In both cases, problems were noted related to the continuous use of the electrode, caused by the adsorption of fluoride ions onto the electrode surface. This problem was solved by using of KOH and Al₂(SO₄)₃ solutions. Good results were obtained for the analysis of real commercial samples.