Spectrophotometric Determination of Trace Amounts of Vanadium(Ⅴ) by Means of Its Catalytic Effect on Oxidation of Azomethine-H by Bromate

A new selective and sensitive kinetic method for determination of trace amounts of vanadium(Ⅴ) (0.5～40ng/ml) based on its catalytic effect on the oxidation of azomethine H by bromate at pH 4.2 and 25 ℃ was reported and its reaction mechanism was studied.The reaction was monitored spectrophotometrically by measuring the increase in absorbance of oxidation product of azomethine H at 436 nm after a fixed time ( 5 min ).The detection limit of the method is down to 2.0×10 -10 g/ml and the relative standard deviation (RSD) for 30 ng/ml of V(Ⅴ) is 0.26 % ( n =6). The effect of foreign ions on V(Ⅴ) determination was also discussed,and the method is mostly free from interferences of other ions.The proposed method was successfully applied to the determination of trace amounts of vanadium in water samples.

Dual-wavelength dual-indicator catalytic kinetic spectrophotometry for determination of trace Ru(Ⅲ)

A new dual-wavelength dual-indicator catalytic kinetic spectrophotometric method for the determination of trace Ru(III)was studied.This method was based on Ru(III)-catalyzing oxidation of Arsenazo I and indigo carmine by potassium bromate in sulfuric acid.The absorbances of the catalytic and noncatalytic systems were measured at 510 and610 nm,respectively.Under the optimum conditions,the linear range of determination is 0–0.12 lgáml-1and the detection limit is 1.21 9 10-4lgáml-1.The method was applied for the determination of trace Ru(III)in ore samples with satisfactory results.

A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species (Se(Ⅳ), Se(Ⅵ)) at trace levels in natural lake and river water samples

A novel catalytic kinetic method is proposed for the determination of Se（Ⅳ）, Se（Ⅵ）, and total inorganic selenium in water based on the catalytic effect of Se（Ⅳ） on the reduction of Celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2-20 and 20-200 μg·L-1 of Se（Ⅳ） for the fixed-time method at 30℃. The experimental and theo- retical detection limits of the developed kinetic method were found to be 0.21 and 2.50 μg·L-1 for the fixed-time method （3 min）. All of the variables that affect the sensitivity at 645 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se（Ⅳ） determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus as long as chelating agents of thiourea and thiosulphate. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The relative standard deviations （RSDs） for ten replicate measurements of 2, 10, and 20 μg·L-1 of Se（Ⅳ） change between 0.35% and 5.58%, while the RSDs for ten replicate measurements of 3, 6, and 12 μg·L-1 of Se（Ⅵ） change between 0.49% and 1.61%. Analyses of a certified standard reference material （NIST SRM 1643e） for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. The Se（Ⅳ）, Se（Ⅵ）, and total inorganic selenium in lake and river water samples have been successfully determined by this method after selective reduction of Se（Ⅵ） to Se（Ⅳ）.

Mechanistic Study and Kinetic Determination of Cu(Ⅱ) by the Catalytic Kinetic Spectrophotometric Method

A highly sensitive and selective catalytic kinetic spectrophotometric method for the determination of Cu(Ⅱ) is proposed. It is based on the catalytic effect of Cu(Ⅱ) on the oxidation of glutathione(GSH) by potassium hexacyanoferrate(Ⅲ) in acidic medium at 25.0℃. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of oxidant at 420 nm using the fix-time method. Under the optimum conditions, the proposed method allows the determination of Cu(Ⅱ) in a range of 0-35.0 ng m L^(-1) with good precision and accuracy and the limit of detection is down to 0.04 ng m L^(-1). The relative standard deviation(RSD) is 1.02%. The reaction orders with respect to each reagent are found to be 1, 1/2, and 1/2 for potassium hexacyanoferrate(Ⅲ), glutathione and Cu(Ⅱ) respectively. On the basis of these values, the rate equation is obtained and the possible mechanism is established. Moreover, few anions and cations can interfere with the determination of Cu(Ⅱ). The new proposed method can be successfully used to the determination of Cu(Ⅱ) in fresh water samples and seawater samples. It is found that the proposed method has fairly good selectivity, high sensitivity, good repeatability, simplicity and rapidity.

Catalytic-kinetic spectrophotometric determination of vanadium (V) based on the Celestine blue-bromate-vanadium (V)-citric acid reaction

A novel sensitive and relatively selective kinetic method is presented for the determination of V（V） based on its catalytic effect on the oxidation reaction of Celestine blue by potassium bromate in the presence of citric acid as an activator. The reaction was monitored spectropho- tometrically by measuring the decrease in absorbance of Celestine blue at a maximum absorption wavelength of 540 nm between 0.5 and 9 min （the fixed-time method） in an H3PO4 medium at 45℃. The effect of various parameters such as concentrations of H3PO4, citric acid, potassium bromate and Celestine blue, ionic strength, reaction temperature and time on the rate of V（V） catalyzed reaction was studied. The method is free from the most interferences, especially from large amounts of V（IV）. The decrease in absorbance is proportional to the concentration of V（V） over the entire concentration range tested （0.025-1.25 lag.mL^-1） with a detection limit of 6.80 tag.L^-1 （according to statistical 3Sblank/k criterion） and a coefficient of variation （CV） of 1.78% （for ten replicate measurements at 95% confidence level）. The proposed method suffers from a few interferences such as Cr（VI） and Hg（Ⅱ） ions. The method was successfully applied to the determination of V（V） in river water, lake water, tap water, natural drinking water samples and a certified standard reference material such as SRM-1640 with satis- factory results. The vanadium contents of natural water samples were detected by using both linear calibration curve and standard addition curve methods. The recoveries of spiked vanadium （V） into the certified standard water sample were found to be quantitative, and the reproducibility was satisfactory. It was observed that the results of the SRM 1640 were in good agreement with the certified value.

Catalytic effects of trace ruthenium on oxidation of dimethyl yellow with bromate and its application

A spectrophotometric method for the determination of ruthenium(III) is described, based on its catalytic effect on the oxidation reaction of dimethyl yellow (DMY) with potassium bromate in an acid solution medium and in the presence of an OP emulsifier (p-iso-octyl phenoxy polyethoxy ethanol) at 100 °C. This reaction was followed spectrophotometrically by measuring the decrease in the absorbance at 530 nm of the catalytic reaction of DMY. The calibration curve for the recommended method was linear in the concentration range over 0.0–1.0 μg/L and the detection limit of the method for Ru(III) was 0.01 μg/L. The method is highly sensitive, selective and very stable and has been successfully applied for the determination of trace amounts of ruthenium in some ores and metallurgy products with the relative standard deviations (RSD) over 1.6%–2.8% and a recovery over 98.7%–104.0%.

A New Reaction for Kinetic Spetrophotometric Determination of Trace Ruthenium——Catalytic Oxidation of Methyl Green by Bromate

A sensitive catalytic spectrophotometric method for the determination of ruthenium （Ⅲ） has been developed, based on its catalytic effect on the oxidation reaction of methyl green with potassium bromate in acid solution medium at 100℃. The above reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 625 nm for the catalytic reaction of methyl green. The calibration curve for the recommended reaction-rate method was linear in the concentration range over 0.00-0.80 μg/L and the detection limit of the method for Ru （III） is 0.006 μg/L. Almost no foreign ions interfered in the determination at less than 25-fold concentration of Ru （Ⅲ）. The method is highly sensitive, more selective and very stable, and has been successfully applied for the determination of trace ruthenium in some ores and metallurgy products.

Determination of Trace Titanium by Catalytic Kinetic Spectrophtometry

The optimum conditions of discoloring reaction of DBM-arsenazo oxidized by potassium bromate and catalyzed by trace titanium(Ⅳ)are studied and a new catalytic-kinetic spectrophotometric method for determination of trace titanium is developed.The linear range of determination of titanium(Ⅳ)is 0-48 ng/mL at 530 nm.The detection limit of the method is 0.084 ng/mL.The method is used for the determination of titanium in water samples and the analytical results are in excellent agreement with those by atomic absorption spectrometry.

Spectrophotometric Determination of Lodine in Soils by Chloramine T-Tetrabase System

Optimized the experimental conditions of determination of trace iodine in soil in chloramine T-Tetrabase system, and analysis the national standards material, the results showed that the measured values was to be identical with recommended values with a detection limit of 0.16 μg/g, and the relative standard deviation was less than 8%, the whole process was short in time and simple, so it was applicable to the determination of trace iodine in batches.

过氧化氢-耐尔蓝体系催化动力分光光度法测定冶炼废水中微量铜

随着水土环境的日益恶化,监控包括铜在内的重金属污染对水土环境的危害越来越受到重视,有的重金属通过食物链以有害浓度在人体内积累,严重危害人体健康。基于在柠檬酸缓冲溶液反应介质中,过氧化氢在Cu(Ⅱ)的催化下能氧化耐尔蓝褪色,其褪色程度与Cu(Ⅱ)含量成正比,从而建立了催化分光光度法测定微量Cu(Ⅱ)的新方法。选择的反应介质柠檬酸缓冲溶液具有某些表面活性剂的作用,浅析了柠檬酸缓冲溶液在工作中对耐尔蓝起增敏作用的原因,且柠檬酸作为植物提取物,具有无毒环保,易于分解,可调节酸度和化学性质稳定等优点。通过实验确定了方法的最大吸收波长为635 nm,柠檬酸缓冲溶液的最佳使用量为1.0 mL,耐尔蓝和过氧化氢的最佳用量分别为1.75和1.0 mL,反应时间和反应温度分别为11 min和90℃,Cu(Ⅱ)含量在0~0.32μg/mL内与吸光度的差值呈线性关系。对铜标准溶液和标准物质进行测定,测定结果的相对误差在2.8%~3.8%,相对标准偏差在3.8%~4.7%,表观摩尔吸光系数为5.0×10^(6)L/(mol•cm)。方法用于废水中微量Cu(Ⅱ)的测定,加标回收率在95.6%~102%。方法具有操作简便、选择性较好、有较灵敏度高、分析成本低、使用的试剂较为环保等优点。

水中碘化物的3种测定方法比较

目的:通过离子色谱法、硫酸铈催化分光光度法、电感耦合等离子体质谱法3种方法测定水中碘化物,通过实验比较,分析3种方法的优缺点。方法:选取质控样品作为实验对象,按照3种方法实验步骤测定各实验组水中碘化物浓度。结果:3种检测方法线性关系均满足实际检测要求,且相关系数R^(2)≥0.999。电感耦合等离子体质谱法检出限为0.6μg·L^(-1),加标回收率为100.8%,相对标准偏差为0.36%~0.45%;硫酸铈催化分光光度法检出限为1.2μg·L^(-1),加标回收率为84.4%,相对标准偏差为0.80%~1.91%;离子色谱法检出限为8μg·L^(-1),加标回收率为91.4%,相对标准偏差为0.23%~1.11%。结论:3种检测方法检测范围广、灵敏度高,且精密度和准确度表现良好,均可准确测定水中碘化物的含量。

Kinetic spectrophotometric method for the determination of cerium(IV) with naphthol green B

A simple and sensitive spectrophotometric method was described for the determination of cerium（IV） based on its catalytic effect on the oxidation of naphthol green B by potassium periodate in the medium of sulfuric acid. The influences of acidity, concentration of reactants, reaction time, reaction temperature, and foreign ions were discussed, and the optimum reaction conditions were established. The reaction was monitored spectrophotometrieally by measuring the decrease in absorbance of naphthol green B at 710 nm after a fixed time （8 min）. The proposed method allowed the determination of cerium（IV） in the range of 0.08-2.4 μg·mL^-1 with good precision and accuracy, and the detection limit was 0.012 μg·mL^-1. The method was applied successfully for the determination of trace cerium in hair samples without previous separation. Recovery experiments were also performed, and the recovery was between 95.7%-111.0%.

A Kinetic Spectrophotometric Method for the Determination of Iron (Ⅲ) in Water Samples

A new kinetic spectrophotometric method has been developed for the determination of iron （Ⅲ）. The method is based on the catalytic effect of iron （Ⅲ） on the oxidation of weak acid brilliant blue dye （RAWL） by KIO4 in acid medium. The advantages of the proposed method are that it is sensitive, accurate, rapid, inexpensive, can be operated under room temperature and has a large determination concentration range compared to other techniques. The obtained optimum conditions are： pH 3.15, RAWL （200 mgL^-1） 5.00mL, Potassium periodate solution （0.01 molL^-1） 0.30mL, phenanthroline （0.02 molL^-1） 1.00mL, reaction temperature 25℃ and reaction time 7 min. With this method iron could quantitively be determined in the range 0.00-0.02 mgL^-1, the detection limit being 4.10 × 10^10gmL^-1. The relative standard deviations （RSD） in five replicate determinations for 3 μgL^-1and 5 μgL^-1 iron （Ⅲ） are 3.1% and 1.9%, respectively. The method has been applied to the determination of iron （Ⅲ） in tap water samples and seawater samples （from the South China Sea）, the recovery rates being 98.0% and 100.5%, respectively.

催化光度法测定伊文思蓝褪色反应速率常数——推荐一个物理化学新实验

介绍了一个关于复杂反应动力学测量的物理化学实验。基于亚硝酸钠作用下溴酸钾氧化伊文思蓝褪色反应,通过测量不同初始反应条件下系统吸光度随时间的变化情况,推导伊文思蓝和溴酸钾的分级数,探讨亚硝酸钠对反应的加速作用,并根据不同温度下的测量数据计算表观反应活化能。本实验可依据学时安排开设为基础性实验或综合设计性实验。两个学期的教学实践表明,作为综合设计性实验,本实验可加强学生对表观速率常数、表观活化能以及催化作用的认识,并促进学生综合实验能力的培养;此外,本实验也可适当精简后作为基础性实验项目“丙酮碘化反应”的替代方案,能克服该实验中存在的反应速率较快不易记录实验数据、碘不易清洗污染比色皿等问题。

类普鲁士蓝纳米酶材料的制备及其酶催化反应动力学探究——推荐一个分析化学综合实验

将类普鲁士蓝纳米酶引入本科实验教学,设计了一个探究性的分析化学综合实验,实验内容包括三种类普鲁士蓝纳米酶材料的制备、表征和酶催化反应速率常数的测定,并将这些纳米酶材料应用于过氧化氢(H2O2)的分析检测。本实验所用试剂价廉易得、反应条件温和、实验现象直观、时间分配合理,适合本科实验教学,用于提升学生的实验技能和科研创新能力。

Catalytic kinetic spectrophotometric determination of cerium

A new procedure for the determination of cerium was established using the catalytic effect of Ce(IV) on the oxidation of tribromoarsenazo(TB-ASA) by potassium bromate.In 0.080 mol/L sulfuric acid medium,the maximum absorption peak of Ce(IV)-(TB-ASA)-KBrO3 system is at 510 nm.The amount of Ce(IV) and the difference of absorbance(△A) showed a good linear relationship over the range of 5.7×10-8-5.1×10-7 mol/L.The regression equation is △A=2.3×10-11 C(C:mol/L)+0.0196,with a regression coefficient of 0.9914 at t...

采用催化热解-冷原子吸收分光光度法测定土壤和沉积物中的总汞研究

工业的快速发展对土壤结构等造成了一定的不良影响,导致生态环境污染日渐严重,影响着经济社会的发展和进步。根据研究调查显示,汞会以各种形态存在于自然界内,而对生态环境造成的影响也存在一定的差异性。因此,在实际发展的过程中,需要测定土壤以及沉积物中汞含量,进而针对实际情况制定解决方法。可以采用催化热解-冷原子吸收分光光度法进行测量,而这主要是因为其操作较为简单,步骤较少,分析消耗时间较短,且测定数据准确性更高,因此被大范围推广和应用。

溴酸钾氧化喹哪啶红催化光度法测定痕量亚硝酸根

基于亚硝酸根对溴酸钾氧化喹哪啶红的催化作用，建立了双波长分光光度动力学测定痕量亚硝酸根的新方法。于４００ ｎｍ测定吸光度△Ａ１，５１０ ｎｍ测定吸光度△Ａ２，以△Ａ＝△Ａ１＋△Ａ２定量。线性范围０．００４～０．１５ ｍｇ／Ｌ；检出限０．００４ ｍｇ／Ｌ０、方法简便，灵敏，准确，选择性好。用于水及蔬菜样品中痕量亚硝酸根的测定，结果满意。

藉溴酸钾氧化酸性间胺黄反应催化光度测定痕量亚硝酸根和硝酸根

本文基于NO2-对KBrO3氧化酸性间胺黄而使其褪色的催化作用，以及NO3-经锌粉还原为NO2-，建立了灵敏的催化光度测定痕量NO2-、NO3-的新方法，并讨论了其动力学条件。测定范围10～90μg／L，方法简便快速、选择性好，用于水及食品中痕量NO2-、NO3-的测定，结果满意。

催化动力学光度法测定痕量铜Ⅱ

研究了在磷酸介质中 ,铜 催化过氧化氢氧化偶氮胂Ⅰ褪色反应的适宜条件与影响因素 ,建立了动力学光度法测定痕量铜 的新方法。方法线性范围为 0～ 1 0 0 μg L ,检出限为 2 .79× 1 0 - 9g mL。该催化反应对Cu 为一级反应 ,表观活化能为 65 .6kJ mol,表观反应速率常数为 9.63× 1 0 - 4s- 1 。用于水样、电镀液和发样中铜 的测定 ,相对标准偏差为 0 .7%～ 4.7% ,标准加入回收率为 97.8%～ 1 0 4.2 %。