Kinetic-Spectrophotometric Determination of Molybdenum(VI) Based on Its Catalytic Effect on the Thionine-Hydrazine Reaction

Abstract

A kinetic method for the determination of trace amounts of Mo(VI) (0.05-4 μg ml^?1) based on its catalytic effect on the reduction of thionine by hydrazine monochloride in strongly acidic media is reported. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of thionine at 605 nm after a fixed time (5 min.). The detection limit of the method is 23 ng ml^?1 and the relative standard deviation (RSD) for 0.05 μg ml^?1 of Mo(VI) is 1.2% (n=7). The method is almost free from interferences, especially from large amounts of tungsten. The procedure was successfully applied to the determination of trace amounts of molybdenum in steel.     

痕量硒的催化褪色法测定

研究了在盐酸介质中，以EDTA作掩蔽剂，痕量硒(Ⅳ)强化催化氯酸钾氧化2-(5-硝基-2-吡啶偶氮)-5-二乙氨基苯酚（5-NO2-PADAP）褪色反应及其动力学条件，建立了催化动力学测定痕量硒的新方法。方法检出限为0.0183цg/L Se(Ⅳ)，该法用于测定人发中痕量硒，结果令人满意。     

Catalytic Spectrophotometric Determination of Titanium(IV) Using Methylene Blue‐Ascorbic Acid Redox Reaction

A highly selective and sensitive catalytic method for the determination of trace amounts of titanium(IV) was developed. The method is based on the catalytic effect of titanium(IV) on the methylene blue‐ascorbic acid redox reaction. The reaction was followed spectrophotometrically by measuring the change in absorbance of methylene blue at 665 nm, 5 minutes after the initiation of the reaction. In this study experimental parameters were optimized and the effect of the presence of various cations and some anions on the determination of titanium(IV) was examined. The calibration graph was linear in the range of 3‐25 ng mL^?1 of titanium(IV). The relative standard deviation for the determination of 10 and 20 ng mL^?1 of titanium(IV) were 2.64% and 1.51%, respectively (n = 8). The detection limit calculated from three times of standard deviation of blank 3S_b was 0.6 ng mL^?1. The method was successfully applied to the determination of titanium(IV) in tap water and ore samples.     

阴离子表面活性剂缔合乙基硫堇光度法测定硫化物的研究

研究了二乙氨基对苯胺与硫化物形成乙基硫堇的显色反应,十二烷基磺酸钠可提高测定S2-的灵敏度。该缔合物在675nm处有最大吸收,摩尔吸光系数为4.25×104L·mol-1·cm-1,S2-测定的线性范围为0～0.8μg/mL。该方法用于天然水中微量硫化物的测定,结果满意。     

催化动力学光度法测定富硒茶叶中痕量硒

本文研究了Se催化过氧化氢氧化甲基橙反应体系测定痕量Se的方法。硒浓度在0～65．7μg／L范围内与褪色反应率lg(A0／A)呈线性关系。方法检出限为0．76μg／L。用于茶叶中硒的测定，结果较满意。     

丁基罗丹明B-高碘酸钾动力学光度法测定铑

报道了以铐催化高碘酸钾氧化丁基罗丹明B为基础的动力学测定痕量铑的方法,详细研究了动力学条件,建立了动力学光度测定痕量铑的新方法,铑浓度在0～180μg/L范围内与log(A_o/A)呈线性关系,检出限为2.84×10~(-7)g/L,该反应对Rh(Ⅲ)或丁基罗丹明B为一级反应,表观活化能为64.04kJ/mol.本方法用于某些催化剂中铑的测定,其相对标准偏差为1.76%～3.46%,回收率为96.8%～104.7%.     

Catalytic Spectrophotometric Determination of an Ultra-Trace Amount of Lead by Reduction of Resazurin by Sodium Sulfide

Abstract

A Kinetic spectrophotometric method for the determination of ultra-trace amounts of lead(II) is described. This method is based on the catalytic action of this ion on the reduction of resazurin by sulfide. The course of the chemical reaction is followed spectrophotometrically by the measurement of reduction in absorbance of resazurin at 605 nm. The calibration range of Pb(II) is dependent on the sulfide concentration.

With this method 1 ng m1^?1 lead can be detected. The method is used for determination of Pb(II) in KNO₃ (Fluka) and in water.     

催化动力学光度法间接测定水中痕量硫离子

在氨水介质中,硫离子可阻抑Fe(Ⅲ)催化过氧化氢氧化二甲酚橙褪色,并且催化体系和阻抑体系在570 nm处吸光度的差值与硫离子浓度呈线性关系,据此建立了阻抑动力学光度法间接测定痕量硫离子的新方法。方法的线性范围为0.0020~0.044mg/L,检出限为1.6×10-9g/mL,对0.040 mg/L硫离子进行10次平行测定的相对标准偏差为2.1%。方法用于废水中硫离子的测定,结果满意。     

Kinetic-Spectrophotometric Determination of Traces of Osmium by Its Catalytic Effect on the Oxidation of Pyrogallol Red by Hydrogen Peroxide

Abstract

A Kinetic-spectrophotometric method for the determination of ultra-trace amounts of osmium(VIII) is described. It is based on the catalytic action of osmium(VIII) on the oxidation of pyrogallol red with hydrogen peroxide, yielding a colorless product in neutral medium. The reaction is followed spectrophotometrically by measuring the rate of change in absorbance at 540 nm and 30°C. Os(VIII) in the range 0.005 -100 ng.ml^?1 can be determined. The proposed method is hardly subject to interferences. The relative standard deviation is 1.5% for 1 ng.ml^?1 of Os(VIII). The kinetic parameters of the catalyzed and uncatalyzed reactions are reported. The detection limit is 1 pg.ml^?1.     

Kinetic Spectrophotometric Determination of Vanadium (V) Based on its Inhibitory Effect on the Thionine – Ascorbic Acid Reaction

ABSTRACT

A simple and sensitive kinetic method for the determination of vanadium(V) based on its inhibitory effect on the reduction of thionine by ascorbic acid at pH=5 is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of thionine at 598 nm after a fixed time (10 min). The calibration graph is linear in the range of 10 ? 120 ng ml^?1 of vanadium(V) and the detection limit is 6 ng ml^?1. The relative standard deviation (RSD) for 80 ng ml^?1 of V(V) was 0.96% (n=10). The method was successfully applied to the determination of vanadium in a certified reference sample.     

微乳液增敏催化荧光光度法测定叶酸的研究

报道了在微乳液介质中,当pH=3.5,以353 nm为激发波长,444 nm为发射波长,在该波长处测定钯(Ⅱ)作为催化剂催化KIO4与叶酸之间反应的荧光强度,从而间接测定叶酸的新方法.在最佳条件下,测定叶酸的线性范围为1.0×10-6～6.0×10-5 mol/L,检出限为1.0×10-7 mol/L,相对标准偏差小于2.20%,加标回收率在97%～105%范围内.CTMAB微乳液的引入可提高体系的灵敏度.结果表明,该方法具有很高的灵敏度、选择性和稳定性,可直接用于各种样品中叶酸的测定.     

催化光度法测定煤矸石中微量铜的研究

在乙酸－乙酸钠介质中痕量铜对抗坏血酸还原二溴对甲基偶氮羟（２－Ｂｒ－ｐＭＡＣ）褪色反应有催化作用,催化程度与Ｃｕ（Ⅱ）量线性相关。借此建立了测定痕量Ｃｕ（Ⅱ）的分光光度法。实验表明,有色溶液所最大吸收波长为５８６ｎｍ,方法检出限为０．０４８μｇ／Ｌ,Ｃｕ（Ⅱ）量在０￣０．８μｇ／５０ｍＬ范围内符合比耳定律,可用于测定煤矸石中的微量铜。     

Flow Injection Determination of Trace Amounts of Iodide with Spectrophotometric Detection by its Catalytic Effect on the 4, 4' – Bis (Dimethylamino) Diphenylmethane-Chloramine T Reaction

ABSTRACT

A simple and accurate flow injection spectrophotometric procedure was developed for the determination of iodide based on its catalytic effect on the oxidation of 4, 4'-bis (dimethylamino) diphenylmethane (tetrabase) by Chloramine T in a weakly acidic solution. The optimum analytical conditions have been established. The linear range of the detection is 4-110 ng/mL, with a limit of detection 3 ng/mL. The method has been used to determine iodide traces in water.     

抗坏血酸的催化动力学光度法测定

建立了一种测定抗坏血酸的方便、快速、高灵敏度的催化动力学光度法。对氨基苯磺酸与亚硝酸根进行重氮化反应生成重氮盐,抗坏血酸对重氮盐的分解有催化作用。利用加入8－羟基喹啉与该重氮盐反应生成偶氮染料来终止反应。在波长495nm处,用1cm比色皿以水作参比测定其吸光度,最佳测定酸度为pH9.0。吸光度与空白体系的差值△A与抗坏血酸的质量浓度呈线性关系。该法测定抗坏血酸的线性范围为0．16－6．3mg/L,检出限为0.005mg/L。利用该法测定了维生素C片剂及荔枝晶中的抗坏血酸含量,并与碘量法进行对照,结果基本吻合。     

催化动力学褪色光度法测定痕量钒

研究了在H3PO4介质中,钒(V)对KBrO3氧化偶氮氯磷mA褪色反应的催化作用及柠檬酸的活化作用,建立了测定钒的新方法。实验发现,无柠檬酸时体系为准零级反应,表观活化能为54.3kJ/mol。在柠檬酸存在下则为准一级反应,表观活化能为30.9kJ/mol,钒的量在0~5.0×10-8g/mL范围内与log(A0/A)呈线性,检出限为5.6×10-11g/mL。在NH4F及尿素存在下,大多数常见离子无干扰。可用于钢样中微量钒的直接测定。     

Bis(2,4,6‐trimethylphenyl)tellurium(IV) Dicyanide: the First Crystal Structure for a Tellurium Cyanide of the Type R2Te(CN)2

The reaction of Mes₂TeF₂ (Mes = 2,4,6‐trimethylphenyl) with trimethylsilyl cyanide yields the corresponding tellurium(IV) dicyanide Mes₂Te(CN)₂. Isolation of suitable crystals allows the determination of the first crystal structure of a compound of the type R₂Te(CN)₂.     

催化光度法测定煤矸石中痕量锡

在浓度为０．０５ｍｏｌ／Ｌ的Ｈ３ＰＯ４介质中,痕量锡对ＮａＨ２ＰＯ２还原罗彤明Ｂ９ＲｈＢ）褪色反应有催化作用,褪色速度ｎ含量线性相关,建立了催化吸光光度法测定痕量Ｓｎ的方法。褪色反应随温度同而加快在沸水浴中５ｍｉｎ,△Ａ可达最大值,流水冷却后吸光度保持１２ｈ基本不变,溶液的最大吸收波长为５５５ｎｍ。方法检出限为０．０３５μｇ／Ｌ,吸光度变化ｎ的质量浓度在０～１．０μｇ／５０ｍＬ范围内符合比耳定律。     

Effect of Temperature on the Binding and Distribution Characteristics of Thionine in Sodium Dodecylsulfate Micelles

The interaction between thionine (a cationic thiazine dye) and anionic surfactant sodium dodecylsulfate in aqueous solution at different temperatures has been studied spectrophotometrically. The absorption spectra were used to quantify the dye/surfactant binding constants and surfactant/water partition coefficients of the dye by applying mathematical models that consider partitioning of the dye between the micellar and aqueous pseudo-phases. The Benesi-Hildebrand equation was applied to calculate the binding constants of thionine to sodium dodecylsulfate micelles over a temperature range of 293 to 333 K. To evaluate the thermodynamic aspects of the interaction of thionine with sodium dodecylsulfate micelles, Gibbs energy, enthalpy and entropy changes were determined. The effect of temperature on the critical micelle concentration of sodium dodecylsulfate in the presence of thionine was also studied and discussed. The binding affinity of thionine to the sodium dodecylsulfate micelles significantly decreased with increasing temperature because of the thermal agitation.