Kinetic Spectrophotometric Determination of Oxalic Acid Based on the Catalytic Oxidation of Bromophenol Blue by Dichromate

 A sensitive catalytic method is developed for the spectrophotometric determination of oxalic acid. It is based on the catalytic action of oxalic acid on a new indicator reaction – the oxidation of Bromophenol Blue by dichromate in dilute sulfuric acid medium. The reaction rate is monitored spectrophotometrically by measuring the absorbance at 600 nm after quenching the reaction with sodium hydroxide. A calibration graph from 0.1 to 8.0 μg mL⁻¹ of oxalic acid and a detection limit of 0.04 μg mL⁻¹ was obtained. The applicability of this method was demonstrated by the determination of oxalic acid in water extracts from vegetables such as spinach, mushrooms and fresh kidney beans. Received October 18, 1999. Revision June 14, 2000.     

Flow Injection Catalytic Determination of Vanadium using the Indicator Reaction between Victoria Blue B and Bromate and A Citric Acid Activator

ABSTRACT

A flow injection catalytic method is proposed for determination of trace vanadium based on its catalytic action on a new indicator reaction between Victoria blue B (VBB) and potassium bromate in the presence of citric acid as an activator and in dilute sulfuric acid medium. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of VBB injected at the maximum absorption wavelength of 618 nm. The detection limit is 0.5 ng ml^?1 and is independent of the initial valence state of vanadium. The relative standard deviation is 1.5% obtained from 11 standard solutions each containing 40 ng ml^?1 of vanadium. The sampling rate is about 15 samples per hour. This method is very simple and has been applied to the determination of trace vanadium in some natural waters with recoveries of 93-103%.     

表面活性剂增敏阻抑动力学光度法测定痕量草酸

在稀盐酸介质中，微量草酸对H2O2氧化靛红的褪色反应有显著的阻抑作用，非离子表面活性剂Triton X-100对此体系有强烈的增敏作用，据此建立了表面活性剂增敏阻抑动力学光度分析测定微量草酸的新方法。方法的线性范围是0．005-0．50mg/L，检出限为0．005mg/L。方法简便，快速，灵敏度高，用于菠菜和尿样中草酸含量的测定，结果满意。     

食品及生物样品中痕量草酸的荧光动力学法测定

拟定了一个荧光动力学测定痕量草酸根的新方法。在硫酸介质中，草酸催化重铬酸钾氧化罗丹明６Ｇ使其荧光猝灭。方法线性范围为０．８－１４．０ｍｇ／Ｌ，直接用于菠菜，人尿中草酸根的测定，获得满意结果。     

茶叶中微量硒的催化光度法测定

用催化光度法测定了23个茶叶样品中向量硒的含量,平均回收率97.2%.变异系数2.13%.     

甲苯胺蓝褪色指示反应动力学光度法测定痕量铁

研究了在硫酸介质中 ,痕量铁催化 H2 O2 和 K2 Cr O7联合氧化甲苯胺蓝褪色反应及其动力学条件 ,建立了催化动力学测定痕量铁的新方法。检出限为9.6 6× 10 -9g· m L-1 ,测定的线性范围为 0～ 0 .6μg/2 5 m L。方法已用于矿泉水、莱服子、菊花、大米和花生中铁的测定     

溴酸钾氧化酸性品红催化光度法测定亚硝酸根

研究了在强酸介质中亚硝酸根催化溴钾氧化酸性品红的褪色反应及其动力学条件，建立了高灵敏测定痕量亚硝酸根的新催化光度法。方法灵敏度为３．７×１０＾－１１ｇ／ｃｍ＾２亚硝酸态氮，线性范围为０．０６－０．４２μｇ／１０ｍＬ，用于测定唾液及硝钾中亚硝酸根。     

痕量草酸的催化荧光分析

在０．０４ｍｏｌ／Ｌ Ｈ２ＳＯ４介质中及８０℃条件下,草酸对Ｋ２Ｃｒ２Ｏ７氧化罗丹明Ｂ这一荧光猝灭反应具有较强的催化作用。以自来水冷却中止反应,采用荧光法研究了催化测定草酸的各种影响因素,建立了一个测定范围和检出限分别为０．０３－３μｇ／ｍＬ和０．０１μｇ／ｍＬ草酸的催化荧光分析法,用于尿样分析,结果满意。     

催化光度法测定水中痕量铜

采用抗坏血酸还原性铬蓝Ｋ的反应,在２,２’－联吡啶活化下被Ｃｕ＾２＋催化加速,建立了催化光度法测定水中痕量铜的新方法。考察了影响反应速度的最佳条件。探讨了反应机理。方法的测定范围是０．００－１．２ｎｇ／ｍＬ,检出限达１．８＊１０＾－１１ｇ／ｍＬ。方法已经用于蒸馏水,自来水中痕量Ｃｕ＾２＋的测定。     

钴(Ⅱ)催化过氧化氢氧化5-Br-TAMB的褪色反应动力学及其应用

研究了NaAc-HAc介质中钴(Ⅱ)催化H_2O_2氧化5-Br-TAMB的褪色的反应,测定了反应动力学参数,探讨了反应机理,并建立了测定痕量钴的新方法。本法检出限为1.8×10~(-10)g/mL,钴(Ⅱ)浓度在0～124.7 ng/12.5 mL范围内与1g(A_0/A)呈良好的线性关系。该体系已用于人发、茶叶中钴的测定,结果满意。     

动力学分光光度法测定微量草酸的研究

本文详细讨论了草酸对锡－苯基荧光酮－溴化十六烷基三甲基铵三元络合物显色反应的催化动力学条件，建立了动力学光度法测定微量草酸的新方法，本法Ｓａｎｄｅｌｌ灵敏度为７．４ｎｇ／ｃｍ＾２，草酸浓度在０－１．０μｇ／ｍＬ范围有良好线性关系，方法可直接用于菠菜中草酸含量的测定。     

溴酸钾氧化茜素绿催化光度法测定痕量亚硝酸根

基于酸性介质溴酸钾氧化茜紊绿反应,提出了测定痕量亚硝酸根新的催化光度法.本法的Sandell灵敏度为9.4×10~(-5)μg/cm~2亚硝酸态氮,测定亚硝酸根量的线性范围为0.01～0.12μg/ml,可用于水样中亚硝酸根测定。     

催化动力学光度法测定痕量锌的研究

利用氨三乙酸为活化剂,锌催化过氧化氢氧化维多利亚蓝B褪色的指示反应,催化光度法测定痕量锌。方法具有一定的选择性。测量的线性范围为0.05~5.50μg.L-1,检出限为2.6×10-11g.mL-1,本法可直接用于头发、茶叶、火腿、牛肉等样品中痕量锌的测定,结果令人满意。     

Catalytic Kinetic Determination of Micro Amounts of Oxalic Acid by Second-Order Derivative Oscillopolarography

ＩｎｔｒｏｄｕｃｔｉｏｎＯｘａｌａｔｅｉｎｎｏｒｍａｌｕｒｉｎｅｉｓｍａｉｎｌｙｆｏｒｍｅｄｂｙｔｈｅｍｅｔａｂｏｌｉｔｅｏｆｅｘｔｒｉｎｓｉｃｆｏｏｄａｎｄｉｎｔｒｉｎｓｉｃｇｌｕｃｏｓｅａｎｄｐｒｏｔｅｉｎ .Ｔｈｅｈｉｇｈｏｘａｌｉｃａｃｉｄｃｏｎｃｅｎｔｒａｔｉｏｎｉｎｕｒｉｎｅｉｓｔｈｅｍｏｓｔｄａｎｇｅｒｏｕｓｆａｃｔｏｒｒｅｓｕｌｔｉｎｇｉｎｋｉｄｎｅｙｓｔｏｎｅａｎｄｕｒｉｎｅｔｒａｃｔｓｔｏｎｅ[1] .Ｔｈｅｙａｒｅｆｏｒｍｅｄｐｒｉｍａｒｉｌｙｂｅｃａｕｓｅｏｆｔｈｅｅｒ ｒｏｒｏ…     

固蓝盐B分光光度法测定药物中抗坏血酸

探讨了一种简便的选择性高的药物中抗坏血酸的测定方法。该方法是基于在酸性介质中抗坏血酸和固蓝盐B的反应,产物的最大吸收为420nm.摩尔吸光系数为1.31×10~4L·mol~(-1)·cm~(-1).方法已应用于某些药物中抗坏血酸的测定,结果与碘量法一致,回收率为98.4％～105％,相对标准偏差低于3.7％。     

动力学催化光度法测定痕量亚硝酸根

磷酸和棉红在１００℃下反应生成天蓝色物质（λｍａｘ＝６７５ｎｍ）,该物质在痕量亚硝酸根的催化下被ＫＢｒＯ３氧化褪色,研究了反应的条件,测定了动力学参数,建立了测定痕量亚硝酸根的方法,方法检出限是４＊１０＾－１０ｇ／ｍＬ,测定范围是０．４０－２０．００μｇ／Ｌ,用于水体中痕量亚硝酸根的测定,结果满意。     

溴酸钾氧化酸性铬蓝K催化光度法测定痕量铜的研究

研究了在稀硫酸介质中，痕量铜催化溴酸钾氧化酸性铬蓝Ｋ的褪色反应，建立了一种高灵敏，高选择性测定痕量铜的新方法，方法的线性范围为０．００１２～０．１４ｍｇ／Ｌ，检出限为４．２×１０＾－７ｇ／Ｌ，用于水，茶叶和粮食中铜的测定，结果满意。     

高碘酸钾氧化丁基罗丹明B催化动力学光度法测定微量芦丁

在氢氧化钠介质中 ,微量芦丁对高碘酸钾氧化丁基罗丹明B褪色反应有明显的催化作用 ,据此建立了测定芦丁含量的催化动力学光度法。讨论了动力学反应参数。该方法的线性范围为 0 .0 2～ 2 .0mg L ;检出限为 1.0× 10 - 2 mg L。方法简便 ,快速 ,灵敏度高 ,用于芦丁片剂中芦丁含量的测定 ,结果令人满意。     

Micro Determination of Ammonia by a Kinetic Spectrophotometric Method

 A simple and sensitive kinetic spectrophotometric method is described for the determination of micro amounts of ammonia. The method is based on the inhibiting effect of ammonia on the oxidation rate of aqua ethylenediamine-tetraacetate chromium(III) [Cr(HEDTA)(H₂O)] with N-bromo succinimide (NBS) to yield chromium(VI). The reaction was followed spectrophotometrically by measuring the rate of change in absorbance with time at 365 nm, which is the maximum absorption wavelength of chromium(VI). Using the recommended procedure, ammonia can be determined up to 153 μg ml⁻¹ with a linear calibration graph and a detection limit of 0.09 μg ml⁻¹. The method was successfully applied to the determination of ammonia in waste water samples. Recovery experiments for the analyzed samples were 97–100% with relative standard deviation, Sr (%) of ≤ 2.9% indicating high accuracy and precision of the proposed method. The interference of various cations and anions in the determination of ammonia was investigated. Received March 30, 2001 Revision September 3, 2001