FIA determination of pyruvate in serum based on direct chemiluminescence oxidation

Chemiluminescence was observed by mixing acidic potassium permanganate solution with pyruvate in the presence of quinine. A new simplified method for pyruvate determination based on this phenomenon was established. The chemiluminescence intensity is a linear function of the concentration of pyruvate in the range of 2 × 10^–6 to 1 × 10^–3 g/mL with a detection limit of 0.8 μg/mL and a relative standard deviation of less than 2.3%. The method has been successfully used to determine pyruvate in serum.     

FIA determination of pyruvate in serum based on direct chemiluminescence oxidation

Chemiluminescence was observed by mixing acidic potassium permanganate solution with pyruvate in the presence of quinine. A new simplified method for pyruvate determination based on this phenomenon was established. The chemiluminescence intensity is a linear function of the concentration of pyruvate in the range of 2 × 10^–6 to 1 × 10^–3 g/mL with a detection limit of 0.8 μg/mL and a relative standard deviation of less than 2.3%. The method has been successfully used to determine pyruvate in serum. Received: 3 April 1998 / Revised: 20 July 1998 / Accepted: 17 September 1998     

Mechanism of the oxidation of organic sulphides by permanganate ion

The kinetics of the oxidation of number of aryl methyl, alkyl phenyl, dialkyl and diphenyl sulphides by permanganate ion to yield the sulphoxides, have been studied. The reaction is first order with respect to the sulphide and permanganate and is independent of hydrogen ion concentration. The reaction exhibited negative polar reaction constants and a small degree of steric hindrance. The lack of solvent isotope effect and the observed solvent effect ( m = 0.39 for McSPh) are explained by an electrophilic attack of permanganate-oxygen on the sulphide yielding a polar transition state. A moderate anchimeric assistance was observed in the oxidation ofo-C00Me ando-C00H substituted methyl phenyl sulphide. A mechanism involving a one-step electrophilic oxygen transfer from permanganate ion to the sulphide and a polar product-like transition state, has been proposed.     

Determination of thiourea and its methyl derivatives by hypoiodite oxidation, and iodine monochloride end point; iodine bromide end point in the titration of thiourea with iodate

Summary Procedures have been described for the quantitative determination of thiourea and its methyl derivatives, wherein iodate, permanganate, and ceric sulphate have been used as direct titration solution, either following preoxidation by alkali hypoiodite via (ICI + KOH) or in case of thiourea, by iodine bromide method. Apart from using standard oxidants the methods have an added advantage of a high conversion factor due to oxidation of sulphur to sulphate. Alternative physical methods of detecting the end point is an added feature of these procedures.The authors wish to express their grateful thanks to Dr. S. S. Joshi, D. Sc. (London), for his kind interest in the work.     

Analysis of mixtures of citric and oxalic acids based on their oxidation with potassium permanganate and manganese(III) sulfate

A determination of mixtures of citric and oxalic acids has been developed based on quantitative oxidation of the two substances with excess potassium permanganate to carbon dioxide and water and on quantitative oxidation of oxalic acid to carbon dioxide and water and of citric acid to carbon dioxide and formic acid with excess manganese(III) sulfate. The content of the two substances in mixtures can be calculated from the different consumption in these two oxidimetric determinations; a single standard solution of potassium permanganate can also be used for the preparation of manganese(III) sulfate.     

The determination of organic substances by the oxidation with permanganate: XVIII. The oxidation of malonic acid

The oxidation of malonic acid with permanganate was studied under various acidity conditions. Analytical procedures, based on oxidation with excess reagent in a sodium carbonate medium and titration of the oxalate or manganese dioxide formed or of unconsumed permanganate, are proposed. On the basis of successive oxidation in sodium carbonate and sulfuric acid media, a titration determination, involving complete oxidation of malonic acid to carbon dioxide and water, was developed.     

Analytical applications of crown ethers : I. Oxidation and determination of benzaldehyde

The use of dicyclohexyl-18-crown-6 (DCC) as charge transfer reagent for the oxidation of benzaldehyde in organic solvents by aqueous solution of potassium permanganate is presented. The oxidation in the presence of a catalyst is found to be quantitative and suitable for the determination of benzaldehyde. Results for the determination of benzaldehyde in benzene and cyclohexane are given.     

Synthesis of Derivatives of (4-Methyl-2-Quinolylthio)acetic and (4-Methyl-2-Quinolylthio)propionic Acids

An efficient synthesis has been developed for derivatives of (4-methyl-2-quinolylthio)acetic and (4-methyl-2-quinolylthio)propionic acids by the reaction of 4-methyl-2-thioxoquinoline with methyl methacrylate, the amide of methacrylic acid, acrylonitrile, ethyl bromoacetate, and ethyl acrylate. The hydrolysis of the resultant intermediates by (quinolylthio)acetic and (quinolylthio)propionic acids gave the corresponding acid products, which are also formed in the reaction of 4-methyl-2-thioxoquinoline with chloroacetic and acrylic acids. The reaction of 4-methyl-2-thioxoquinoline with allyl bromide was studied. The potassium permanganate oxidation of the resultant 2-allylthio-4-methylquinoline led to (4-methyl-2-quinolylthio)acetic acid.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 403–406, April, 2005.     

高锰酸钾-甲醛化学发光体系测定甲氧氯普胺

基于在甲醛的作用下,高锰酸钾对甲氧氯普胺的氧化作用而产生化学发光的现象,建立了一种新的用流动注射-化学发光法测定甲氧氯普胺含量的方法.该方法测定甲氧氯普胺的线性范围为0.2~100 mg/L,检出限为0.1 mg/L.对于8 mg/L的甲氧氯普胺标准溶液连续11次测定的相对偏差为1.2%.该方法可用于对制药废水、片剂和针剂中甲氧氯普胺含量的测定.     

Chemiluminescence (CL) emission generated during oxidation of pyrogallol and its application in analytical chemistry. I. Effect of oxidant compound

An investigation of chemiluminescence (CL)-emission generated by the oxidation of pyrogallol using various inorganic oxidant compounds is reported in this F.I.A.-merging zone application. The oxidant compounds that showed measurable CL-emission were permanganate, periodate, hypochlorite anions, cerium(IV) and hydrogen peroxide. The different oxidant compounds showed CL-emissions at different pH-ranges. The CL-emission was limited by the inner filter effect and this was more intense for oxidants of selective oxidation. Kinetic effects were also found in the case of oxidation by permanganate. Plots of CL-emission against pH give evidence of speciation and or deactivation mechanism effects. The analytical parameters for the determination of the oxidants are given. Sensitivities of 895 600, 19 500, 33 723, 10 680 and 56 703 mV M(-1) were found for the determination of permanganate, cerium(IV), periodate, hypochlorite and hydrogen peroxide, respectively. The calibration curves of the oxidant determination were generally S-shaped; the S-shaped calibration curve of periodate was closer to a straight line relationship while that of hypochlorite was almost a straight line; detection limits in the range of 10(-4) M oxidant concentration were found for nearly all oxidants. The analytical parameters for determination of pyrogallol by the CL-emission generated through oxidation by the different oxidants at optimum conditions were 1.16x10(6) mV M(-1) for permanganate; 0.086x10(6) mV M(-1) for cerium(IV); 0.91x10(6) mV M(-1) for periodate; 0.012x10(6) mV M(-1) for hypochlorite; and 0.25x10(6) mV M(-1) for hydrogen peroxide. The detection limit was 1.0x10(-4) M. The nearly straight-line relationship (initial part of the plot) for CL-emission with oxidant concentration gives an indication that the CL-reaction of pyrogallol oxidation by hypochlorite proceeds through a process that involves energy transfer while the pronounced S-shaped curve produced by permanganate gives the indication that the reaction proceeds through a process that does not involve energy transfer according to the mathematical model of CL-emission that controls the F.I.A.-merging zone technique of the flow apparatus used in this work. The sequence of completeness of the oxidation process by each oxidant was MnO(4)(-)>H(2)O(2)>IO(4)(-)>OCl(-); the stoichiometric quantity of the oxidant per pyrogallol molecule for the rapid part of the overall oxidation by each different oxidant was attempted; this is an index-value of the oxidation state of the fluorescent excited molecule. Finally, the impact of the above findings for further analytical applications is discussed.     

Investigation of the detection limit for the determination,by pyrolysis-capillary GC,of the thickness of ultra thin PMMA layers coated on to PET film

The determination of nanometer thick layers of poly(methyl methacrylate) coated on to the surface of poly(ethylene terephthalate) film has been investigated by high resolution pyrolysis gas chromatography without sample pretreatment or modification of the instrumentation used. A good linear relationship was observed between the quantity of the characteristic pyrolysate and the thickness of the poly(methyl methacrylate) layer; the detection limit was sufficient to enable the quantitation of poly(methyl methacrylate)-to-poly(ethylene terephthalate) film thickness ratios of 1:20000 in composite materials.     

Determination of the purity of methyl nitrite

The purity of methyl nitrite prepared by the esterification of methanol with aqueous nitrous acid was determined by absorbing gaseous samples in solutions of acidic potassium permanganate and hydriodic acid. Nitrate formed in the oxidation reaction was determined by steam distillation, and iodomethane formed in hydriodic acid was determined by gas-liquid chromatography. The method was used to evaluate purification procedures.     

Effect of organosilicon chain-transfer agents on the heat resistance of vinyl polymers

The effect exerted on the resistance of polymers to thermal oxidation degradation by organosilicon hydrides used as chain-transfer agents in polymerization of styrene, methyl methacrylate, and vinyl acetate was examined.     

进口甲基丙烯酸甲酯中阻聚剂快速测定方法及其作用机理研究

建立了气相色谱法和高效液相色谱法快速测定甲基丙烯酸甲酯(MMA)中阻聚剂.气相色谱采用HP-INNOWAX色谱柱分离样品中杂质,液相色谱采用XDB-C18柱同时配置XDB-C18保护柱,直接对样品进行分析.结果表明,气相色语法和高效液相色谱法均具有线性关系好、回收率高等优点,方法的相对标准偏差(RSD)分别为0.53%...     

Correlations between radical distributions and structural defects of squalane and poly(methyl methacrylate) glasses in the oxidation kinetics of radicals

The kinetics have been studied for two processes whose limiting stage is the diffusion of molecular oxygen: (i) oxidation of radicals after irradiation; and (ii) quenching of phenanthrene phosphorescence. The processes were studied in glassy squalane and poly(methyl methacrylate) matrices. Comparison between the kinetic properties of these processes allowed us to conclude about predominant stabilization of radicals near structural defects of glass. In squalane this manifests itself in anomalously high value of reaction radius for oxidation of radicals and in poly(methyl methacrylate) in quantitative difference in the parameters of distribution in rate constants for processes (i) and (ii).     

Preparations of 4‐Substituted 3‐Carboxypyrazoles

The scopes of three synthetic methods reported for the preparation of an array of 3‐pyrazolecarboxylates featuring substituents on position 4 were investigated. The first one is based on the potassium permanganate oxidation of methylpyrazoles. The second starts with the condensation between DMF dimethylacetal and ethyl pyruvate and is followed by the addition of hydrazine hydrochloride. The last one makes use of the cycloaddition of diazomethane on acrylate esters followed by a bromine‐based oxidative rearrangement into 4‐substituted 3‐pyrazole esters.     

Chemiluminescence during the oxidation of alcohols by permanganate: application to the determination of ethanol in gin

Chemiluminescence is observed during the oxidation of ethanol with potassium permanganate under very acidic conditions. Factors affecting the chemiluminescence signal are discussed. Based on this chemiluminescence reaction, a method for the determination of alcohol in gin was developed. The method, which has a detection limit of 0.3% (v/v) and a relative standard deviation of about 1% at 40.0% (v/v), was used in the determination of ethanol in three different brands of gin with no sample preparation.     

Sorption of cobalt on modified clinoptilolites

A method of radioactivation analysis has been developed for the substoichiometric determination of cobalt, copper and manganese in glass and glass-making materials. The substoichiometric extraction of cobalt with α-nitroso-β-naphthol was studied and simple procedures are suggested for the determination of the three elements. Cobalt is extracted substoichiometrically as α-nitroso-β-naphtholate into chloroform from solution of pH 6.2, copper as dithizonate in carbon tetrachloride from weak acidic solution, and manganese as tetraphenylarsonium permanganate into chloroform after oxidation to permanganate. Contents from 2 ppm to 3 ppb of cobalt, copper and managanese were analysed in glass-making materials, and it is shown that the method for their determination is reliable and superior in accuracy and reproducibility.     

On the maximum spreading diameter of impacting droplets on well-prepared solid surfaces

This paper presents a systematic study of liquid droplet impact on three polymer surfaces: poly(methyl methacrylate), poly(methyl methacrylate/n-butyl methacrylate), and poly(n-butyl methacrylate). Changing from one surface to the next represents an incremental variation in solid surface tensions of 5-6 mJ/m2. These surfaces were prepared through careful experimental procedures that were used for the determination of solid surface tensions from contact angles. Our data for the maximum spreading diameter of water and formamide impacting on these surfaces were compared with those predicted from literature models. Of the models selected, we modified the model of Pasandideh-Fard et al. [Phys. Fluids 1996, 8, 650] and the results yielded a least error of only 5.09 +/- 5.05% in the determination of the maximum spreading diameter. The improved model was also compared with literature data, and good agreement was found. Of course, any such comparisons would rely on accurate experimental impact dynamics data on carefully prepared surfaces.