动力学分光光度法快速测定高pH值

传统的pH值玻璃电极传感器在pH 1·0~12·0的范围内具有很好的准确性,但在pH<1·0和pH>12·0的条件下会产生“酸误”和“碱误”[1-3]。氢氧化钠是最常用的化学试剂之一,因此它的准确测定在各种工业过程如产品的质量控制,环境污染控制,以及设备腐蚀控制过程中等具有重要作用。已     

Simultaneous Determination of Micro Bromide and Iodide by Kinetic Spectrophotometric Method

ABSTRACT

ABSTRACTA new kinetic spectrophotometric method for the simultaneous determination of concentrations of micro bromide and iodide has been proposed. It is based on their catalytic effects on the reaction of m-cresol purple oxidized by potassium periodate in hydrochloride acid medium. The reaction rate was monitored by measuring the decrease in absorbance at 528nm and the increase in absorbance at 455nm. The total difference in absorbance of the sum of bromide and iodide is identical with determination of bromide was carried out after Cr(VI) oxidized I? to I₂, and I₂ was removed by extraction with CCI₄, and the amount of iodide was measured by subtracting the absorbance change of bromide from the total absorbance change in the presence of bromine and iodide. The optimum conditions influencing the reaction rate were studied. The linear range of determination is 0～4.0μg/ml for Br? and 0～3.0 μg/ml for I?. The detection limits are 0.032μg/ml for Br? and 0.059 μ/ml for I?. The method was successfully applied to the determination of micro amounts of bromide and iodide in food and life samples.     

新催化动力学光度法测定微量铁的研究--棓花青-O2指示反应体系

在 p H 7.0的磷酸盐缓冲体系中 ,微量铁 ( )能显著催化溶解氧氧化木立口 花青褪色。研究了该指示反应的催化动力学行为 ,建立了测定微量铁的新催化动力学分析法 ,方法线性测定范围 0 .0 5～ 0 .6μg· m L- 1 ,检出限为 0 .0 1 μg· m L- 1 。本法选择性和重现性好 ,反应体系简单易于控制。用其测定了自来水、人发及面粉等样品中的铁 ,结果满意。     

化学计量学-动力学分光光度法同时测定两种糖皮质类激素

在碱性介质中,高锰酸钾能将糖皮质类激素(醋酸泼尼松和地塞米松)氧化,而本身被还原成绿色的锰酸钾,基于这一反应,本文提出了同时测定醋酸泼尼松和地塞米松的化学计量学-动力学分光光度法.研究发现反应体系在610 nm处有一个吸收峰,实验以该波长为检测波长,优化实验条件.在该条件下,检测醋酸泼尼松和地塞米松的线性范围分别为0....     

Kinetic Spectrophotometric Determination of Ranitidine

Two spectrophotometric methods were developed for the determination of ranitidine. The first method was a kinetic spectrophotometric method based on the catalytic effect of ranitidine on the reaction between sodium azide and iodine in an aqueous solution. The calibration graph was linear from 4–24 μg/mL. The drug was determined by measuring the decrease in the absorbance of iodine at 348 nm using a fixed time method. The decrease in the absorbance after 1 minute from the initiation of the reaction was related to the concentration of drug. The detection limit of the procedure was 0.76 μg/mL. The proposed procedure was successfully utilized in the determination of the drug in pharmaceutical preparations with mean recovery in the range of 99.83 ? 101.16%. The second method is a colorimetric method, which depends on the measurement of absorbances of tris (o‐phenanthroline) iron(II) [method 2A] and tris (bipyridyl) iron(II) [method 2B] complexes at 512 nm. The complexes obeyed Beer's law over the concentration range of 2–16 μg/mL and 4–40 μg/mL for methods 2A and 2B, respectively. The developed method has been successfully applied for the determination of ranitidine in bulk drugs and pharmaceutical formulations. The common excipients and additives did not interfere in its determination.     

Determination of Sulfide in Spring and Wastewater by a New Kinetic Spectrophotometric Method

A simple, rapid, and sensitive method has been developed for the determination of trace amounts of sulfide based on its reaction with thionine. The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of the dyestuff at 600 nm by the fixed time method. After optimization of the measuring conditions the calibration curves were found linear up to 38.0 ppm (four regions), and the theoretical limit of detection was 0.076 ppm and the relative standard deviation for determination of 1.0 ppm sulfide (n = 10) was found to be 2.7%. The proposed method was applied successfully to the determination of sulfide in spring water and wastewater samples.     

Spectrophotometric Determination and Kinetic Studies of Condensation of Aromatic Aldehydes with 2-Thiobarbituric Acid

The condensation reaction of 2-thiobarbituric acid with aromatic aldehydes in ethanol has been investigated spectrophotometrically at 30-50°;C. The reaction was catalyzed by HCl solutions. The reaction follows overall second order kinetics, first order each in reactant. Activation parameters have been calculated from the dependence of the rate constants on temperature. The rate of condensation increases with the presence of electron donating groups on the aromatic ring of the aldehyde. The rate-determining step involves dehydration of the aldol intermediate. Based on this reaction, determination of 13 aromatic aldehydes in a concentration range of 0.149-76 mu;g/ml is proposed.     

Spectrophotometric Method for the Rapid Determination of Microgram Amounts of Ethionamide

Abstract

Spectrophotometric Method for the Rapid Determination of Microgram Amounts of Ethionamide

A simple and sensitive method for the determination of microgram amounts of ethionamide is described. Ethionamide is converted to corresponding 2-ethyl-γ-pyridyl thiohydroxamic acid which gives a purple violet colour (Λmax 510 nm) with ferric chloride in acidic medium. This forms the basis for the quantitative determination of ethionamide in its pure form and in tablet form. The influence of substrates, commonly employed as excipients, is studied. An attempt has been made to determine ethionamide in the presence of other antitubercular drugs.     

Selective Kinetic Spectrophotometric Determination of Nitrite in Food and Water

Abstract

A highly selective and sensitive method for the kinetic spectrophothometric determination of sub-microgram amounts of nitrite has been development based on its reaction with Nile blue 2B in acidic medium. The reaction is monitored spectrophotometrically at 595 nm at a fixed time of 4.5 min. The change in absorbance at 595 nm is related to the concentration of nitrite in the range 0.005 - 1.100 μg.ml^?1 The detection limit is 0.001 μg.ml^?1. The relation standard deviation is 1% for 0.020 μg.ml^?1 of nitrite for ten replicate measurements. Most common anions and cations do not interfere. The procedure was applied to the determination of trace amounts of nitrite in sausage and water.     

动力学光度法测定痕量镉的研究

本研究了氨水介质中，痕量镉阻抑过氧化氢氧化偶氮胂１褪色的新指示反应及其动力学条件，建立了动力学光度法测定痕量镉的新方法，方法检出限为２．７×１０＾－１２ｇＣｄ＾２＋／ｍｌ，测定范围为０－１．０μｇＣｄ＾２＋／２５ｍｌ。     

Spectrophotometric Determination of Ampicillin with Some Nitro Compounds

Abstract

A spectrophotometric procedure for the determination of ampicillin (Amp.) in pure solutions and in its pharmaceutical preparations has been developed. This new method offers advantages of simplicity, rapidity and stability in comparison with the official BP (1980) method. The proposed method is based on the formation of a colour condensation product through the reaction of ampicillin and nitrobenzene derivatives in an alkaline aqueous-acetone medium 40% (v/v). Beer's law is obeyed in the range 0.5–28 μg ml^?1. The colours were produced within 20 min. after heating at 60±5°C and stable for at least 6 h. The method is relatively accurate (recovery 100±2%) and precise (RSD 1.9%) and can be used successfully for the preparation of capsules, syrup and ampoules.     

Novel Spectrophotometric Method for Determination of Macro-paracetamol via Reaction with Bromine

The reaction between Br2 and paracetamol(p-AAP) leads to the formation of a coloured product, which can be used for spectrophotometric determination of the p-AAP content in its pure form and in different pharmaceutical preparations with p-AAP. The stoichiometric composition of the reaction was found to be n(p-AAP)∶n(bromine)=1∶3. The effects of pH and time on the spectra of p-AAP-bromine redox reaction product were studied. The interference of different additives on the measured spectra of the obtained product was also studied. The results obtained by the present method were compared with those obtained by the standard method. The F- and t- test values were calculated for both of the applied procedures and they met a confidence level of 99%. The proposed procedure actually needs no separation of these drugs from their sources before analysis and was unaffected by interference of other phenolic compounds. The proposed method is simpler and faster than the repoeted ones.     

阻抑动力学光度法测定痕量间二硝基苯的研究

研究发现 ,在硫酸介质中 ,痕量间二硝基苯能灵敏地阻抑 Fe3+催化高碘酸钾氧化甲基兰褪色。研究了该阻抑褪色反应的最佳条件及动力学参数 ,建立了一种测定痕量间二硝基苯的新方法。该法测定线性范围为 0 .0～ 8.0μg/L,检出限为 1 .6× 1 0 - 6 g/L。用于环境水样中间二硝基苯的测定 ,结果满意     

Extractive Spectrophotometric Determination of Ondansetron by Ion-Pair Formation with Bromocresol Green

Abstract

An empirical spectrophotometric procedure for the determination of the antiemetic ondansetron is carried out. The method is based on the formation of a 1:1 ion pair with bromocresol green in the pH range over 3.2 – 4.4, extraction into chloroform layer and spectrophotometric measurement at 420.8 nm. The calibration graph is linear over the range 0.1 – 20 μg ml^?1 ondansetron, with a relative standard deviation of 2.7%; the influence of foreign substances is also studied. The method is applied to ondansetron determination in human urine.     

Kinetic Spectrophotometric Determination of Famotidine in Pharmaceutical Preparations

A kinetic method for the accurate and sensitive determination of famotidine has been described. The method is based on the alkaline oxidation of famotidine with potassium permanganate at a fixed time of 10 min. The formed manganate ion is measured at 610 nm. The concentration of famotidine is calculated using the calibration equation for the fixed time method. Beer's law was obeyed in the range of 1–10 μg/mL and the R.S.D. (n = 10) was 0.47%. The method has been applied successfully to commercial tablet dosage form.     

动力学分光光度法测定痕量亚硝酸根和硫氰酸根的研究

基于亚硝酸根对溴酸钾氧乙基橙反应的催化作用及硫氰酸根对此反应的抑制作用，建立了动力学光度法测定痕量亚硝酸根和硫氰酸根的新方法，测定亚硝酸根的线性范围为５－１００μｇ／Ｌ，测定硫氰酸根的线性范围为３－１２μｇ／Ｌ，用于湖水和蔬菜中的亚硝酸根量及化学试剂和尿中的硫氰酸根测定，结果满意。     

A New Simple and Sensitive Spectrophotometric Procedure for Determination of Adrenaline

Abstract

A new spectrophotometric procedure is described for the determination of ppm concentrations of adrenaline. The procedure is based on formation of Tris(O-phenanthroline)iron(II) complex (ferroin) upon reaction of adrenaline with an iron(III)-O-phenanthroline mixture in slightly acidic medium. The ferroin complex is then spectrophotometrically measured at 510 nm. In addition to being facile and rapid, the procedure is sufficiently selective and accurate, being particularly suitable for the assay of adrenaline in pharmaceutical formulations; the standard deviation didnot exceed 0.64%.     

Two-Wavelength Spectrophotometric Determination of Food Color Mixtures with the Function Generator

Abstract

Though the two-wavelength spectrophotometric determination¹ without the function generator permitted measurement of one component contained in two-component mixtures without sample pretreatment, it required proper wavelength selection and could not analyze some kinds of samples. The method of two-wavelength spectrophotometric determination with the function generator herein reported has succeeded in eliminating these limitations thus permitting the analysis of many kinds of samples. This method has further made it possible to measure one component contained in three-component mixtures.     

Kinetic Spectrophotometric Determination of Thiols and Ascorbic Acid

Abstract

This paper describes a kinetic spectrophotometric method for the determination of L‐ascorbic acid (AA) and thiols (RSH). Absorbance of Fe(II)‐phen complex formed during the reaction of AA or RSH with Fe(III)‐phen was continuously measured at 510 nm by double‐beam spectrophotometer with flow cell. For determination some thiols, the catalytic effect of Cu²⁺ ions was used. AA and RSH can be determined in concentration ranges from 4.0×10^?6 to 4.0×10^?5 M and from 8.0×10^?6 to 8.0×10^?5 M, respectively. The applicability of the proposed method was demonstrated by determination of chosen compounds in pharmaceutical dosage forms.