A micro and ultramicro test for sulphur dioxide

Summary A very sensitive reaction for sulphur dioxide is proposed for use on the micro and ultramicro scales. Interference by cyanide, sulphide, and thiosulphate can be prevented. Sulphite can be distinguished from bisulphite.

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Zusammenfassung Eine sehr empfindliche Reaktion zum Nachweis von Schwefeldioxid im Mikro- und Ultramikromaßstab wurde vorgeschlagen. Störungen durch Cyanid, Sulfid und Thiosulfat lassen sich vermeiden. Sulfit kann von Hydrogensulfit unterschieden werden.

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Résumé On propose une réaction très sensible pour la recherche de l'anhydride sulfureux à l'échelle micro et ultramicro. On peut éviter l'interférence avec les cyanures, les sulfures et les thiosulfates. On peut distinguer les sulfites des bisulfites.

     

Multiple determinations in the micro Dumas nitrogen method

Summary A multiple analysis method for the Dumas nitrogen determination has been described. The furnace is provided with eight combustion tubes arranged in a circle around the axis of the furnace. An improved nozzle-type nitrometer, without ground joints, has been designed. The multiple determinations are simultaneously carried out as in usual method, permitting thirty two analyses in a 7-hour working day. The standard deviation-error of estimate from 88 analyses in routine work is ±0.12% N.

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Zusammenfassung Ein Verfahren zur gleichzeitigen Durchführung mehrerer Stickstoffbestimmungen nachDumas wurde beschrieben. Der Verbrennungsofen kann acht Verbrennungsrohre in gleichmäßiger Entfernung von seiner Längsachse aufnehmen. Ein verbessertes Düsenazotometer ohne Schliffverbindungen wurde konstruiert. Die Analysen werden gleichzeitig in der üblichen Art durchgeführt, so daß im 7stündigen Arbeitstag 32 Bestimmungen möglich sind. Die mittlere Abweichung von 88 Analysen im Routinebetrieb betrug ± 0,12% N.

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Résumé On a décrit une méthode d'analyse multiple pour le dosage de l'azote selonDumas. Le four est muni de huit tubes á combustion disposés suivant un cercle autour de l'axe du four. On a construit un nitromètre perfectionné de type à étranglement, sans joints rodés. On effectue simultanément les dosages multiples comme dans la méthode habituelle, ce qui permet de réaliser trente deux analyses en une journée de travail de 7 heures. L'écart type calculé à partir de 88 analyses dans un travail en série est de ±0,12% N.

     

State-of-the-art in organic elemental micro and ultramicro analysis

Summary Nernst developed a quartz torsion microbalance in 1903. In consequence of this pioneering work, Emich in the Technical University of Graz, Austria, had systematized a series of chemical operations in microscale as well as a microchemical analysis. Further advances in technique and method of organic microanalysis had been accomplished by Pregl in Graz in 1912. His work had been strongly supported by a new microbalance which was known as Kuhlmann microbalance. Pregl's original methods of analysis were arranged and published in 1916 as Die quantitative organische Mikroanalyse. It is still noteable that the Nobel prize of 1933 had been presented to Dr. Pregl. In accordance with a combination of electronic microbalance and computer techniques, organic elemental microanalysis has grown to include advanced instrumentation and on-line computation. Successful adaptation of microchemical analysis has expanded today not only to pure organic compounds, but on industrial intermediates, polymers, food additives and many other compositions. The paper includes a discussion of the relative merits of traditional and modern analytical techniques together with the progression of microbalances. Recent developments in organic micro and ultramicro analysis in Japan are also described.     

Detection of gases on the micro and ultramicro scales

Summary Micro and ultramicro techniques have been worked out for the detection of gases liberated in chemical reactions. One of the methods is performed on the stage of a microscope. The apparatus used is simple and easily made, and the methods are rapid, simple, and reliable. The minimum amount detectable is less than 1 ng, and the sample volume required varies from 1–100 nl. A simple piston attachment for transfer of liquids is also described. A stereoscopic microscope with coordinate movement of its optics is strongly recommended. The application of the techniques to the detection of ammonia and cyanide is described.

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Zusammenfassung Mikro- und Ultramikroverfahren zum Nachweis von Gasen, die bei chemischen Reaktionen frei werden, wurden ausgearbeitet. Eines der Verfahren wird auf dem Mikroskoptisch durchgeführt. Das dazu nötige Gerät ist einfach und leicht herstellbar. Die Verfahren sind rasch, einfach und zuverlässig. Die nachweisbare Mindestmenge ist geringer als 1 ng, die benötigte Probemenge beträgt 1 bis 100 nl. Ein einfaches Gerät zur Übertragung der Flüssigkeiten wurde beschrieben. Ein Stereomikroskop mit koordinierter Optik wird nachdrücklichst empfohlen. Die Anwendung auf den Nachweis von Ammoniak und Cyanid wurde beschrieben.

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Résumé On a mis au point les techniques de détection à l'échelle micro et ultramicro des gaz libérés dans les réactions chimiques. L'une des réactions s'effectue sur la platine d'un microscope. L'appareillage utilisé est simple et préparé rapidement; les méthodes sont rapides, simples et sûres. On peut déceler moins de 1 ng et le volume-échantillon nécessaire varie de 1 à 100 ml. On décrit également un dispositif simple avec piston pour transférer le liquide. On recommande fortement l'emploi d'un microscope stéréoscopique avec mouvement coordonné de son optique. On décrit l'application des techniques de détection de l'ammoniaque et des cyanures.

     

Construction of small data bases for trace element determinations

Construction of a small data base intended as a model for personal use in the area of trace element determinations is described. A MELCOM 7000 computer is used and several types of on-line conversational retrieval systems are discussed.     

Rapid method for trace determination of organochlorine pesticides and polychlorinated biphenyls in yogurt

A new multiresidue method was developed for the analysis of 19 organochlorine pesticides and 6 polychlorinated biphenyls in yogurt. The sample was extracted twice with acetone by homogenization with an Ultra-Turrax dispersing unit, and the combined extracts were filtered. The extract was then purified by reversed-phase C18 columns and subjected to further cleanup with neutral alumina columns. The residues were determined by gas chromatography with electron capture detection. After the method was optimized, it was validated by determination of recovery percentages, precision (repeatability and reproducibility), and sensitivity (detection and quantitation limits) with yogurt samples fortified at 10 and 1 microg/kg concentration levels. The recovery of 23 organochlorine residues ranged from 77 to 95% at a level of 10 microg/kg, from 74 to 102% at a level of 1 microg/kg, and between 54 and 61% for dieldrin and alpha-endosulfan. The method is repeatable and reproducible, with relative standard deviation values <19% for all residues except dieldrin. Detection and quantitation limits were between 0.02 and 0.62 microg/kg. The analytical method proposed was quick, accurate, repeatable, and reproducible for the determination of organochlorine residues in yogurt samples.     

Organic quantitative analysis. XL — Conductometric micro and ultramicro determination of carbon

Summary A rapid method is described for the determination of 0.3–3 mg of carbon in organic samples by catalytic combustion in the presence of Co₃O₄, and conductometric measurement of the amount of carbon dioxide produced. Interfering elements are dealt with in the usual way, and the carbon dioxide is absorbed in a specially designed absorption vessel. The accuracy and precision of the method are practically constant over the whole range of 0.3–3 mg carbon, and are at least as good as those of the gravimetric micro methods; the method is therefore particularly useful since it gives excellent results with both micro and ultramicro sample weights.

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Zusammenfassung Ein rasches Verfahren für die Bestimmung von 0,3 bis 3 mg Kohlenstoff in organischen Substanzen durch katalytische Verbrennung über Co₃O₄ und konduktometrische Messung des Kohlendioxids wurde beschrieben. Störende Elemente werden wie üblich behandelt. Das Kohlendioxid absorbiert man in einem speziellen Gefäß. In dem angegebenen Bereich ist die Genauigkeit des Verfahrens praktisch gleichbleibend gut und dem gravimetrischer Mikromethoden vergleichbar. Das Verfahren ist besonders deswegen nützlich, weil es sowohl mit Mikro- wie mit Ultramikroeinwaagen ausgezeichnete Ergebnisse liefert.

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Résumé On décrit une méthode rapide pour le dosage de 0,3 à 3 mg de carbone dans les échantillons organiques par combustion catalytique en présence de Co₃O₄ et mesure conductimétrique de la quantité de gaz carbonique produite. Les éléments qui interfèrent sont éliminés de la manière habituelle et le gaz carbonique est absorbé dans un vase à absorption spécialement conçu. L'exactitude et la précision de la méthode sont pratiquement constantes dans tout le domaine de 0,3–3 mg de carbone et sont au-moins aussi bonnes que celles des micro-méthodes gravimétriques; la méthode est donc particulièrement utile puisqu'elle donne d'excellents résultats avec des poids d'échantillon micro et ultramicro.

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XXXIX: Chemický prmysl, to be published.     

An automatic potentiometric analyzer for atmospheric hydrogen fluoride determinations

An automatic potentiometric analyzer for the determination of atmospheric hydrogen fluoride is described. Hydrogen fluoride is collected from the air, which is pumped at 25 l min^-1, in a thin layer of sodium carbonate in a spiral absorber, and measured every hour by washing the absorber with a citrate buffer and measuring the fluoride with a fluoride-selective electrode. The analytically useful range is 0.1–15 μg HF m^-3.     

Rapid method for the determination of trace fluoride and activation of ion-selective electrode.

A method for activating ISE is proposed that can allow determination of the fluoride concentration at ng mL(-1) level with good precision and accuracy. Fluoride ISE is activated in 0.5 mol L(-1) HClO4 medium and then fluoride is determined in the same medium. The linear range for the determination of fluoride is between 1.00 x 10(-2)-1.00 x 10(-7) mol L(-1), and the detection limit of the method is 1.0 ng mL(-1). The advantage of this method is that it is free from the use of TISAB solution while being, time-saving and labor-saving. A mechanism study of the activation of FISE in HClO4 medium is explained. The method has been used for the determination of trace fluoride in milk and flour with satisfactory results.     

A chemiluminescence photometer for trace chromium(III) determinations

The design of a simple chemiluminescence photometer is described. The sample is injected into a spectrophotometric cell containing the reagents, and the resultant chemiluminescence peak is recorded along with the peak height and peak area. The instrument includes a temperature-controlled cell holder with stirring capabilities. The determination of p.p.b. levels of chromium(III) is described. Chromium(III) enhances the chemiluminescence reaction of luminol and hydrogen peroxide in basic solutions. Useful calibration curves are obtained from 4 · 10^-9 to 10^-4 M Cr(III); 5 · 10^-10 M is the detection limit. Chromium(III) is determined in natural water samples and NBS Orchard leaves.     

New method for the spectrophotometric determination of ultramicro amounts of copper

A deep yellow colour is formed by the reaction with phenol and chloramine-T in the presence of copper, and this reaction is used for the photometric determination of copper. An aqueous solution of copper and the reagents at pH 11.5-11.6 is heated. The molar absorptivity at 410 mmu, is 2.32 x 10(6). The method has been used satisfactorily to determine ultram amounts of copper in high-purity silicon.     

Recent developments in atomic spectrometry methods for elemental trace determinations

Summary Methods for atomic spectrometry are discussed in view of progress for elemental trace analysis and with special reference to progress in power of detection and in analytical reliability as well as with respect to economic aspects. Optical methods basing on atomic emission, absorption and fluorescence principles as well as related techniques (optogalvanic spectroscopy and coherent forward scattering), X-ray spectrometry and mass spectrometry are treated. The state-of-the-art, trends of development and new techniques such as special sample introduction for plasma spectrometry, glow discharges, laser enhanced ionization spectrometry with a thermionic diode, X-ray spectrometry with total reflection, plasma and glow discharge mass spectrometry are drawn up. Their potential interest from the point of power of detection, multielement capacity, interferences, capabilities for micro- and local analysis and speciation is compared with that of other methods for elemental analysis.

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Neue Entwicklungen atomspektrometrischer Methoden für die Elementspurenanalyse

Zusammenfassung Für die atomspektrometrischen Methoden wird der Fortschritt im Hinblick auf Nachweisvermögen, analytische Zuverlässigkeit und Kosten diskutiert. Optische Methoden wie die Emissions-, Atomabsorptionsund Fluorescenzspektrometrie, aber auch verwandte Techniken (Optogalvanik und kohärente Vorwärtsstreuung), neue röntgenspektrometrische Methoden und massenspektrometrische Verfahren werden behandelt. Es werden der Stand der Technik, die Entwicklungstendenzen und neue Techniken wie spezielle Probenzuführungsmethoden für die Plasmaspektrometrie, Glimmentladungen, die laserinduzierte Ionisationsspektrometrie, die Röntgenfluorescenzspektrometrie mit Totalreflektion und der Einsatz des induktiv gekoppelten Plasmas und von Glimmentladungen als Ionenquellen für die Massenspektrometrie dargestellt. Das Nachweisvermögen, die Multielementkapazität, die Interferenzen, die Möglichkeiten für Mikro- und Verteilungsanalysen sowie für die Bestimmung der Bindungsform bei den Methoden der Atomspektrometrie werden mit denen anderer Methoden für die Bestimmung der chemischen Elemente verglichen.

     

高频燃烧红外吸收法测定钢铁中超低碳硫

通过对气体净化,坩埚处理,试样处理及称样量选择,助熔剂种类及用量等因素的优化,建立了钢铁中超低含量碳硫的测定方法,实验结果表明：比较器水平设为1%,分析时间设为45 s,坩埚在1350 ℃下预烧45 min,选择钨作为助熔剂且使用前在140 ℃烘3 h,助熔剂用量为1.5 g,称样量为0.5 g时,是分析钢铁中碳硫含量在0.01～0.001 %的最佳条件,方法重复性好,准确度高,在实际操作中切实可行。     

Rapid automatic potentiometric method for analytical control in the manufacture of extraction phosphoric acid

A rapid automatic method for determination of free sulphuric acid in the manufacture of extraction phosphoric acid from apatite has been developed. It is based on potentiometric titration combined with the Gran approach for linearization of the titration curve. The analysis is done with an automatic potentiometric titrator controlled by an HP-85 microcomputer. BASIC software activates the system to perform the data acquisition and calculations, and the whole operation takes only 7-8 min.     

Application of neutron activation analysis for trace element determinations in biological materials

Over the past three decades, more and more interest has been focused on trace eleemnts in biological materials. This increasing interest has gone hand in hand with the continuous improvement of analytical techniques. Neutron activation analysis has proven to be a most suitable method for the quantitative determination of a wide variety of trace (0.01–100 μg g^?1) and ultratrace (<0.01 μg g^?1) elements in biological materials. This technique has even played a preponderant role in this field.     

Evaluation of septa quality for automatic SPME-GC-MS trace analysis

The vials used for the preparation of breath samples for automated solid-phase microextraction-gas chromatography-mass spectrometry analysis are crimped with septa. These septa often emit specific volatile organic compounds (VOCs) confounding the measurement results of breath samples. In the current paper, 14 different brands of magnetic caps with silicone-polytetrafluoroethylene (PTFE), butyl-PTFE, or butyl rubber septa were tested. The total emission of septa over a 4 h period was also evaluated. The tested septa emitted 39 different compounds, which are mainly hydrocarbons, alcohols, and ketones. Acetone and toluene are the most abundant out-gassing products. The concentration of acetone was in the range from 55 to 694 ppb for butyl-PTFE septum (brand 14) and butyl rubber (brand 10), respectively. The measured toluene amount was 69-1323 ppb for the septum brand 14 and brand 8 (silicone-PTFE), respectively. Generally, the butyl rubber septa released higher amounts of contaminants in comparison to the silicone ones.