Determination of quinol in volumetric analysis

Summary A short review is given of the literature concerning volumetric determination of quinol. Comparison of various titration procedures and their possible application shows that the cerimetric determination must be preferred for the standardization of pure quinol solutions; when determining the amount of quinol in mixtures, however, one must usually be content with a titration procedure using dichromate, vanadate, ferricyanide and zinc or bromate-bromide, which each have their special applications. In these cases it is recommended to compare the results of the method chosen with the results of a cerimetric determination using a pure quinol solution.

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Zusammenfassung Es wird ein kurzer Überblick über die Möglichkeiten zur volumetrischen Hydrochinonbestimmung gegeben. Ein Vergleich verschiedener Verfahren zeigt, daß zur Titerstellung reiner Hydrochinonlösungen die Cerimetrie am besten geeignet ist. Zur Hydrochinonbestimmung in Mischungen muß jedoch eine Titration mit Dichromat, Vanadat, Hexacyanoferrat(III) und Zink oder Bromat-Bromid verwendet werden, von denen jede ihre besondere Anwendungsmöglichkeiten besitzt. In diesen Fällen ist es empfehlenswert, die erhaltenen Werte mit denen einer cerimetrischen Bestimmung an einer reinen Hydrochinonlösung zu vergleichen.

     

Conformational analysis of benzenediols: pyrocatechol,resorcinol and hydroquinone

Molecular orbital calculations are carried out for pyrocatechol, resorcinol and hydroquinone. The structural parameters, stable conformations, potential barrier heights, dipole moments and charges for these molecules are discussed. Only one stable isomer for pyrocatechol, three for resorcinol and two for hydroquinone are established.     

Alkylation of pyrocatechol and resorcinol by camphene

Alkylation of pyrocatechol and resorcinol by camphene in the presence of the organoaluminum catalysts aluminum phenoxide and aluminum isopropoxide was studied. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 205–208, May–June, 2007.     

Titrimetric determination of quinol

A critical review is presented of the literature on the titrimetric determination of quinol. For the standardisation of pure quinol solutions the cerimetric titration procedure can be recommended, but in the presence of various organic contaminants vanadate, hexacyanoferrate(III) plus zinc and dichromate are the best titrants.     

Quantitative enantiomeric analysis of chlorcyclizine,hydroxyzine, and meclizine by capillary electrophoresis

A simple capillary zone electrophoresis method was developed for the quantitative enantiomeric analysis of piperazine antihistamines with teratogenic suspicion in animals. Enantioseparation of chlorcyclizine, hydroxyzine, and meclizine was performed in glycine buffer (0.6 mol L^-1; pH 3.00) with sulfated -cyclodextrin (5 mg mL^-1) as a chiral selector; and the separated drugs were monitored by ultra-violet detector. The lower quantitation of the individual enantiomer is attainable at 10 µmol L^-1, using an achiral piperazine drug (cyclizine) as internal standard. The method is simple and rapid with a short run time (<5 min) for the analysis of chlorcyclizine, hydroxyzine or meclizine enantiomers.     

气相色谱法同时测定西草净、丁草胺和噁草灵

 采用气相色谱法,以癸二酸二正丁酯为内标物,对新研制的复合型稻田除草剂26％丁··西乳油进行了一次性定量分析。色谱条件为5％SE-302m×3mm的玻璃柱,柱温为210℃,检测温度为230℃。方法的回收率为98．62％～100．77％,线性相关系数大于0．999。方法准确、简便、快速。     

Rotamers and vibrations of resorcinol obtained by spectral hole burning

(1 + 1)REMPI and hole-burning spectra of resorcinol are recorded. Under the conditions of free-jet expansion only two rotamers significantly contribute to the spectrum. The bands of the REMPI spectrum can be assigned as electronic origins and vibrational transitions of the two rotamers. In order to determine the stabilities of the rotamers ab initio Hartree-Fock calculations using the 6–31G(d, p) and 6–311 + + G(d, p) basis sets are carried out. The data of a complete vibrational analysis at the 6–31G(d, p) level are compared with experimental infrared and Raman frequencies. The REMPI signals are assigned using the normal vibrations calculated for the electronic ground state.     

Quantitative thermal analysis,II

Some problems on adjustment of the equipment and on data evaluation, in view of the equations derived earlier for the calculation of specific heat and heat of transformation are discussed. It is shown that quantitative determinations are possible also if the adjustment is non-ideal and that both air and an inert material, respectively, may be used as reference material.

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Zusammenfassung Gewisse Probleme des Adjustierens der Ausrüstung und der Auswertung der Daten in Hinsicht auf die früher abgeleiteten Gleichungen zur Errechnung der spezifischen und Umwandlungswärmen wurden besprochen. Man bewies, daß quantitative Bestimmungen auch bei nichtidealem Adjustieren möglich sind bzw. daß Luft und Inertstoff gleichwie als Referenzstoffe dienen können.

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Résumé On discuté divers problèmes relatifs à la mise au point de l'appareillage et à l'évaluation des données, dans l'optique des équations déduites précédemment pour le calcul de la chaleur spécifique et de la chaleur de transformation. On montre qu'il est possible de faire des déterminations quantitatives même si la mise au point n'est pas idéale et que l'on peut utiliser comme substances de référence l'air aussi bien qu'un corps inerte.

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Quantitative thermal analysis,III

The effect of some experimental factors on quantitative determinations of heat of transformation are discussed. It is shown on the example of solid phase invariant processes that by using the equation derived earlier by the authors, a number of factors, viz. mass, bulk density, thermal conductivity and specific heat of the sample, as well as the position of the junction of the thermocouple, need not be taken into account.

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Zusammenfassung Der Einflu\ verschiedener experimentaler Faktoren auf die quantitative Bestimmung der UmwandlungswÄrme wurde besprochen. Am Beispiel von invarianten VorgÄngen in fester Phase wurde gezeigt, da\ bei Anwendung einer von den Verfassern früher abgeleiteten Gleichung gewisse Faktoren, wie Masse, Schüttgewicht, thermische LeitfÄhigkeit und spezifische WÄrme der Probe, weiterhin Lage der Verkoppelung des Thermoelements nicht zu berücksichtigen sind.

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Résumé On a discuté l'influence de divers facteurs expérimentaux sur la détermination quantitative de la chaleur de transformation. On a montré sur l'exemple des processus invariants en phase solide et en utilisant une équation déduite précédemment par les auteurs, que l'on ne doit pas prendre en consideration des facteurs comme masse, densité apparent, conductivité thermique et la chaleur spécifique de la matière examinée, en outre la position de la sondure du thermocouple.

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顺序注射阻抑动力学光度法测定环境水样中的间苯二酚

在酸性条件下,利用间苯二酚能抑制罗丹明B和溴酸根反应速率的原理,联用顺序注射技术建立了非平衡态快速测定痕量间苯二酚的新方法.优化了顺序注射流路参数、试剂用量,考察了共存物的影响.在最佳条件下,该法测定间苯二酚的线性范围为0.20～3.00 μg/mL,检出限为0.09 μg/mL,每小时可测定40个样.     

Quantitative analysis of sodium by (p, γ) reactions

Thick target excitation yield of prompt gamma-rays from sodium bombardment by fast protons are measured and tabulations are given. The application of the prompt gamma-ray technique to elemental determination of sodium in solid sample is developed, sensitivity limits are discussed. Example of concentration determinations and depth profile analysis in glass, mineral, and biological sample are given.     

Quantitative analysis of phosphorus by (p, γ) reactions

Measured values of the intensities of characteristic γ-rays emitted under the bombardment of protons on a thick target of phosphorus are tabulated. The intensity of each characteristic γ-ray is measured and used for quantitative analysis of phosphorus in any sample with a sensitivity of 50 to 1000 ppm.     

Spectrophotometric determination of phenol and resorcinol by reaction with p-aminophenol

Based on the reaction with p-aminophenol, a series of procedures have been developed for the spectrophotometric determination of phenol and resorcinol. Three basic approaches have been studied: (i) a batch procedure, using the dissolved oxygen as oxidant, (ii) a stopped-flow procedure by use of KIO(4) as oxidant and (iii) a flow injection (FI) procedure developed in the presence of KIO(4). Phenol can be accurately determined at 626 nm, in the stopped-flow mode, after a reaction time of 45 min in 0.005M NaOH, 0.004M KIO(4) and 500 mug/ml of PAP. The development of a manifold, which incorporates a sample parking, is a convenient approach which makes it possible to measure, in the stopped-flow mode, four solutions in one hour. The limit of detection of this method corresponds to 64 ng/ml of phenol Resorcinol can be determined by FI at 540 nm in 0.006M NaOH, 0.0002M KIO(4) and 50 mug/ml PAP with a limit of detection of 6.6 ng/ml and a sample throughput of 300 injections per hour. A combination between the FI procedure for the determination of resorcinol and the stopped-flow procedure for phenol determination provides accurate results in the analysis of spiked samples containing both phenol and resorcinol.     

Kinetics and mechanism of oxidation of quinol by alkaline hexacyanoferrate(III)

The reaction between quinol and alkaline hexacyanoferrate(III) at constant ionic strength gives p-benzoquinone. The rate of the reaction was first order in the concentrations of substrate, oxidant and alkali. The slow step of the reaction involves the formation of the p-benzosemiquinone radical, which was detected by esr spectroscopy as a five-line spectrum with peak intensity ratios of 14641.

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Quantitative analysis of silicon-oxynitride films by EPMA

Thin films of silicon oxynitride with diverse compositions were prepared by de-magnetron sputtering of silicon, utilising oxygen and nitrogen gas flows and the sputtering power to vary the composition. In order to investigate the composition of these films, a method of analysis by electron probe micro analysis with energy dispersive detection was developed and the figures of merit were compared to the wavelength dispersive method used by other authors. The precision and repeatability of the results are evaluated and the accuracy is checked by comparison with Rutherford backscattering and nuclear reaction analysis. Energy dispersive X-ray spectrometry was proven to be applicable to analyse silicon oxynitride films of any composition yielding quantitative results for nitrogen and oxygen as well as silicon. Besides the good analytical performance, electron probe micro analysis with energy dispersive X-ray spectrometry has turned out to be a non-destructive, quick, easy to use and cost effective tool for the routine analysis of light elements in thin films.