Determination of arsenic in organic compounds

Summary Methods are described for the determination of arsenic in organic compounds. Following oxygen flask combustion using a nichrome gauze arsenic is estimated either by titration of arsenic(III) with iodine or by titration of iodine liberated from iodide by arsenic(V). An alternative colorimetric procedure involving measuring the absorbance of molybdenum blue is used following open tube digestion in the absence of halogens or sealed tube digestion in the presence of halogens.

---

Bestimmung von Arsen in organischen Verbindungen

Zusammenfassung Nach Verbrennung im Sauerstoffkolben mit einem Nickeldrahtnetz als Katalysator wird das Arsen entweder durch. Titration des As(III) mit Jod oder durch Titration des durch As(V) aus Jodid ausgeschiedenen Jods bestimmt. Ein anderes Verfahren beruht auf der kolorimetrischen Bestimmung von Methylenblau nach Verbrennung im offenen Rohr bei Abwesenheit von Halogenen oder im verschlossenen Rohr bei Anwesenheit von Halogenen.

     

Determination of nitrogen in organic compounds

Summary A simplified method is described for the electrolytic generation of oxygen for use in the micro-Dumas determination of nitrogen. A flowmeter with an adjustable range is also described.

---

Zusammenfassung Eine vereinfachte Anordnung zur elektrolytischen Sauerstoffentwicklung für die Verbrennung stickstoffhältiger Substanzen nach dem MikroDumas-Verfahren in einer Kohlendioxyd-Sauerstoff-Atmosphäre wird angegeben. Außerdem wird ein justierbarer Strömungsmesser beschrieben.

---

Résumé On décrit une méthode simplifiée pour la production électrolytique de l'oxygène utilisé dans le microdosage de l'azote suivantDumas. On décrit aussi un fluxmètre à échelle réglable.

     

Determination of fluorine in organic and organometallic compounds

Summary A method is described for the determination of fluorine in organic and organo-metallic compounds. Following oxygen-filled flask combustion in a silica flask, an aliquot of the absorbent solution is analysed for fluoride by a standard addition technique utilising a fluoride selective electrode.

---

Fluorbestimmung in organischen und metallorganischen Verbindungen

Zusammenfassung Nach Verbrennung im sauerstoff-gefüllten Quarzkolben wird ein gemessener Teil der Absorptionslösung nach der Standard-Zusatztechnik mit Hilfe einer fluorspezifischen Elektrode analysiert.

     

Determination of phosphorus in organic compounds by NMR

Summary A method is described for the microdetermination of phosphorus by FTNMR in organic compounds containing transition metals. Approximately 10 mg of compound is digested for the determination and 2 mg Cr added as relaxation agent.

---

Zusammenfassung Eine Mikromethode zur Bestimmung des Phosphors in organischen, Übergangsmetalle enthaltenden Verbindungen mit Hilfe der Fourier-Transform P³¹ kernmagnetischen Resonanz wurde beschrieben. Ungefähr 10 mg Substanz werden mit Schwefelsäure-Perchlorsäure aufgeschlossen und 2 mg Cr^III werden als Relaxans zugegeben.

     

Determination of the solubility of organic compounds

Summary Estimations of solubility are carried out by observing with a magnifying lens the substance while it is exposed to air laden with vapor of the solvent.

---

Zusammenfassung Teilchen der Substanz werden auf einem schmalen Objektträger abwechselnd einem mit dem Dampf des Lösungsmittels beladenen und einem reinen Luftstrom ausgesetzt, während sie durch ein Vergrößerungsglas beobachtet werden. Der zur Verflüssigung erforderliche Zeitraum ist offen-kundig durch den Löslichkeitsgrad bedingt.

---

Résumé Une petite particule de substance placée sur une petite lame porte-objet est soumise alternativement à un courant d'air chargé de la vapeur du solvant et à un courant d'air pur tandis qu'elle est observée à l'aide d'une loupe. Le temps nécessaire à la liquéfaction dépend évidemment du degré de solubilité de la substance.

     

Determination of carbon and hydrogen in organic fluorine compounds

A rapid determination of carbon and hydrogen in organic fluorine compounds is described. Magnesium oxide is used both as an absorbent for fluorine and as an aid to complete combustion. The time required for one determination in series is under 30 min. The method is very widely applicable.     

Determination of deuterium in organic compounds by infrared spectrophotometry

The Trenner-Arison-Walker method for the micro-analysis of deuterium in organic compounds involves oxidation of the compound with copper oxide in a sealed tube, collection of the water by vacuum distillation, and analysis of the water by infrared spectrophotometry. Experience in applying this technique to a variety of organic compounds in our laboratory has suggested a number of procedural modifications. These principally affect the methods of sample handling and water collection. Difficulties associated with temperature changes on the spectrophotometry of the deuterium-enriched water are overcome by differential analysis against natural-abundance water using a double-beam spectrophotometer.     

Determination of volatile organic compounds by headspace trap

A new analytical method for the determination of halogenated and aromatic volatile organic compounds in groundwater, mineral water, and drinking water at concentrations ranging between 1-10000 ng/L is developed. A new type of headspace sampler that combines static headspace sampling with a trap is used, yielding very low detection limits and good repeatability without carryover effects. An unexpected transformation of 1,1,2,2-tetrachloroethane into trichloroethene is observed and explained.     

Determination of volatile organic compounds in human breath for Helicobacter pylori detection by SPME-GC/MS

Helicobacter pylori living in the human stomach release volatile organic compounds (VOCs) that can be detected in expired air. The aim of the study was the application of breath analysis for bacteria detection. It was accomplished by determination of VOCs characteristic for patients with H. pylori and the analysis of gases released by bacteria in suspension. Solid-phase microextraction was applied as a selective technique for preconcentration and isolation of analytes. Gas chromatography coupled with mass spectrometry was used for the separation and identification of volatile analytes in breath samples and bacterial headspace. For data calculation and processing, discriminant and factor analyses were used. Endogenous substances such as isobutane, 2-butanone and ethyl acetate were detected in the breath of persons with H. pylori in the stomach and in the gaseous mixture released by the bacteria strain but they were not identified in the breath of healthy volunteers. The canonical analysis of discrimination functions showed a strong difference between the three examined groups. Knowledge of substances emitted by H. pylori with the application of an optimized breath analysis method might become a very useful tool for noninvasive detection of this bacterium.     

Determination of organic compounds in water using dispersive liquid-liquid microextraction

A new microextraction technique termed dispersive liquid-liquid microextraction (DLLME) was developed. DLLME is a very simple and rapid method for extraction and preconcentration of organic compounds from water samples. In this method, the appropriate mixture of extraction solvent (8.0 microL C2Cl4) and disperser solvent (1.00 mL acetone) are injected into the aqueous sample (5.00 mL) by syringe, rapidly. Therefore, cloudy solution is formed. In fact, it is consisted of fine particles of extraction solvent which is dispersed entirely into aqueous phase. After centrifuging, the fine particles of extraction solvent are sedimented in the bottom of the conical test tube (5.0 +/- 0.2 microL). The performance of DLLME is illustrated with the determination of polycyclic aromatic hydrocarbons (PAHs) in water samples by using gas chromatography-flame ionization detection (GC-FID). Some important parameters, such as kind of extraction and disperser solvent and volume of them, and extraction time were investigated. Under the optimum conditions the enrichment factor ranged from 603 to 1113 and the recovery ranged from 60.3 to 111.3%. The linear range was 0.02-200 microg/L (four orders of magnitude) and limit of detection was 0.007-0.030 microg/L for most of analytes. The relative standard deviations (RSDs) for 2 microg/L of PAHs in water by using internal standard were in the range 1.4-10.2% (n = 5). The recoveries of PAHs from surface water at spiking level of 5.0 microg/L were 82.0-111.0%. The ability of DLLME technique in the extraction of other organic compounds such as organochlorine pesticides, organophosphorus pesticides and substituted benzene compounds (benzene, toluene, ethyl benzene, and xylenes) from water samples were studied. The advantages of DLLME method are simplicity of operation, rapidity, low cost, high recovery, and enrichment factor.     

Determination of bromine in organic compounds by high-performance liquid chromatography

A method is proposed for the determination of bromine in organic compounds (which may also contain chlorine and iodine) by oxygen-flask combustion of the compound followed by pre-column reaction of bromide with acetanilide and 2-iodosobenzoic acid to form 4-bromoacetanilide which is then chromatographed on an ODS column with a mobile phase of methanol: water, 65:35 v/v, detection at 240 nm, and 4-N-acetylaminotoluene as internal standard. The method is rapid and precise (RSD 相似文献   

Determination of sulfur in organic compounds using a barium-selective electrode

A procedure was developed for determining sulfur (>1.5 abs %) in sulfur-containing organic compounds. The procedure was based on the combustion of a sample portion in a flask filled with oxygen followed by the potentiometric titration of sulfate ions with barium nitrate in a water-acetone solution. In distinction from analogous procedures, halogens and metals contained in the analyzed compound did not interfere with the determination of sulfur. The error of determination was below 3 rel %.     

Determination of cholesterol in human hair using gas chromatography-mass spectrometry

This work describes a sensitive method for determining cholesterol in human hair using GC-MS. In this study, we used a very small amount of hair, only 1 mg, to quantify cholesterol. We also can achieve more effective purification and a good recovery over 92% with solid-phase extraction using an Oasis HLB cartridge. The intra-day and inter-day precision and accuracy values were less than 7.08%. Cholesterol was determined to be in the range of 355-1693 microg/g in healthy human hair. We tested the concentration correlation between the serum and hair to examine the feasibility of using the hair cholesterol level as an index of the serum cholesterol level. The correlation between the serum cholesterol was 0.86 (r-value) in patients with hypercholesterolemia. This finding indicates that, in the clinical field, hair could replace serum in cholesterol level measurement.     

Determination of selenium and tellurium in organic compounds and organic materials — A review

Summary A review is given of methods available for determination of selenium and tellurium in organic compounds and organic materials. The various techniques for decomposition (wet digestion, combustion and bomb fusion) are covered, and the investigational work on decomposition methods is mentioned. The various types of reactions which have been used as methods of finish are also discussed. Methods which involve only physical measurements are not included.

---

Zusammenfassung Eine Übersicht über verfügbare Methoden zur Bestimmung von Selen und Tellur in organischen Verbindungen und Materialien wurde gegeben. Die verschiedenen Verfahren zur Zerstörung (nasse Veraschung, Verbrennung und Bombenaufschluß) wurden berücksichtigt und die über Zerstörungsmethoden vorliegenden Publikationen angeführt. Die für die Endbestimmung verwendeten Reaktionstypen wurden erörtert. Physikalische Meßmethoden wurden nicht eingeschlossen.

     

Determination of the solubility of organic compounds. II

Summary In general, solid particles liquify when they are exposed to air laden with the vapor of a liquid in which they are soluble. There are exceptions, however, which may be explained by assuming the formation of a solvate.

---

Zusammenfassung Feste Teilchen verflüssigen sich im allgemeinen, wenn sie Luft ausgesetzt sind, die mit dem Dampf einer Flüssigkeit geladen ist, in der sie löslich sind. Es wurden aber Ausnahmen gefunden, die möglicherweise durch die Bildung von Solvaten erklärt werden können.

---

Résumé Généralement, les particules solides se liquéfient si elles sont exposées à l'air chargé de la vapeur d'un liquide dans lequel elles sont solubles. Il existe cependant des exceptions que l'on peut expliquer en supposant la formation de solvates.

---

---

On the occasion of the hundredth return ofFriedrich Emich's birthday.

---

The authors wish to express their appreciation to ProfessorO. F. Steinbach for his suggestions and advice.     

Determination of volatile organic compounds from truffles via SPME-GC-MS

Volatile organic compounds (VOCs) of nine Tuber species and two corresponding forms are identified via solid-phase microextraction-gas chromatography-mass spectrometry analysis. Seventy-five compounds are identified. The most abundant are dimethylsulphide, 2- and 3-methylbutanal, 2-methylpropanol, and butanone.     

Determination of fluorine in organic compounds by epithermal neutron activation analysis

Classical activation analysis of fluorine by thermal neutrons has a limited application because of frequent interference from chlorine, the short half life²⁰F (11.4 s) and too high dead time of detectors. A procedure is described for fluorine determination using¹⁹F (n,p)¹⁹O reaction. Use of a boron carbide shield has no effect on the activity of¹⁹O (boron ratio −1) but considerably reduces background and interference due to¹⁸O (n, γ)¹⁹O reaction. The technique has been successfully applied to the determination of fluorine in organic compounds even in the presence of large amounts of chlorine and oxygen.     

Determination of the deuterium content in organic compounds by gas chromatography

A gas-chromatographic method was developed for determining deuterium in organic compounds at its atomic fraction of 1 to 99%. The accuracy of the method is 0.1–0.5%.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 8, 2004, pp. 1346–1350.Original Russian Text Copyright © 2004 by Egorov, Matyukhova, Demidova, Platonov, Proskuryakov.