Studies on oxygen determination in organic microanalysis. II. On the microanalysis of oxygen by decrease in the quantity of anhydro-iodic acid

Summary Oxygen in organic compounds is determined by means of the decrease in weight of anhydro-iodic acid. Anhydro-iodic acid is stable in air and can be used for a long time. Satisfactory analyses are obtained.

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Zusammenfassung Sauerstoff kann in organischen Verbindungen durch Messung des Gewichtsverlustes der Anhydrojodsäure bestimmt werden. Diese ist an der Luft beständig und bleibt lange Zeit verwendungsfähig. Zufriedenstellende Analysenergebnisse werden erhalten.

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Résumé Le dosage de l'oxygène dans les composés organiques est effectué par la détermination de la diminution de poids de l'acide anhydroiodique. L'acide anhydroiodique est stable à l'air et peut être employé pendant des temps très longs. Des résultats satisfaisants ont été obtenus par les auteurs.

     

The microanalysis of fluorine-containing organic compounds. II. the determination of fluorine

Summary The compound is decomposed by fusion with metallic sodium or potassium in a nickel bomb of special design, and the fluorine is titrated with thorium nitrate solution. Several modifications of this titration procedure were first examined as a means of completing the determination, but only one was found suitable, i. e. back-titration of a comparison solution with a standard sodium fluoride solution.When nitrogen and sulphur, which form cyanide and sulphide ions, are present, the procedure has to be modified slightly to overcome their interference.

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Zusammenfassung Organische Fluorverbindungen werden durch Schmelzen mit metallischem Natrium bzw. Kalium in einer Nickelbombe besonderer Konstruktion zerstört und das Fluor mit Thoriumnitratlösung titriert. Einige Modifikationen dieses Titrationsverfahrens wurden zunächst geprüft, aber nur eine davon erwies sich endgültig als für die Bestimmung geeignet: die Rüektitration einer Vergleichalösung mit einer Standardlösung von Natriumfluorid.Bei Gegenwart von Stickstoff und Schwefel bilden sich Cyanidbzw. Sulfidionen, deren störender Einfluß durch eine kleine Abänderung des Verfahrens ausgeschaltet werden muß.

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Résumé Les composés organiques fluorés sont décomposés par fusion avec le sodium métallique ou le potassium dans une bombe de nickel de construction spéciale et le fluor est titré avec le nitrate de thorium en solution. Plusieurs modifications de ce mode de titrage furent d'abord examinées pour terminer le dosage, mais un seul fut trouvé convenable, le titrage par retour d'une solution de comparaison avec une solution de fluorure de sodium.Quand l'azote et le soufre qui forment des ions cyanhydriques et suifhydriques sont présents, le procédé doit être légèrement modifié afin d'empêcher leur interférence.

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The paper byR. Belcher andR. Goulden, Mikrochem.37, 679 (1951) is considered as Part I of this series.     

Basic investigations for laser microanalysis: II. Laser-induced fluorescence in laser-produced sample plumes

Laser-induced fluorescence in laser-ablated standard steel samples was measured, in order to study the atomization and propagation properties of the plasma plume and the analytical figures of merit of the method. As an example, measurements were performed exciting silicon, chromium or boron atoms by pulsed dye laser radiation.     

Amplification reactions in microanalysis. A survey

Amplification reactions have been known for a long time, even if not always under this name. They are an alternative to analyze very small amounts of substance. Definitions and basic terms are given and the various possibilities for such reactions so far known are discussed, not all of the methods described here are of practical use.     

Surface microanalysis with slow electrons.

Microanalysis on the 10-nm level using imaging, diffraction, and spectroscopy of slow photo-emitted and reflected electrons is discussed. The instrumentation that uses a cathode lens is briefly reviewed, and a number of applications illustrate the power of this microanalysis method.     

X-ray microanalysis of human cementum.

An energy dispersive x-ray microanalysis study was performed throughout the total length of cementum on five impacted human teeth. Mineral content of calcium, phosphorous, and magnesium were determined with an electron probe from the cemento-enamel junction to the root apex on the external surface of the cementum. The concentration profiles for calcium, phosphorous, and magnesium were compared by using Ca/P and Mg/Ca atomic percent ratio. Our findings demonstrated that the Ca/P ratio at the cemento-enamel junction showed the highest values (1.8-2.2). However, the area corresponding to the acellular extrinsic fiber cementum (AEFC) usually located on the coronal one-third of the root surface showed a Ca/P media value of 1.65. Nevertheless, on the area representing the fulcrum of the root there is an abrupt change in the Ca/P ratio, which decreases to 1.3. Our results revealed that Mg(2+) distribution throughout the length of human cementum reached its maximum Mg/Ca ratio value of 1.3-1.4 at.% around the fulcrum of the root and an average value of 0.03%. A remarkable finding was that the Mg/Ca ratio pattern distribution showed that in the region where the Ca/P ratio showed a decreasing tendency, the Mg/Ca ratio reached its maximum value, showing a negative correlation. In conclusion, this study has established that clear compositional differences exist between AEFC and cellular mixed stratified cementum varieties and adds new knowledge about Mg(2+) distribution and suggests its provocative role regulating human cementum metabolism.     

高效液相色谱法测定化妆品中9种防晒剂

采用高效液相色谱法测定化妆品中二苯酮-3、3-亚苄基樟脑、4-甲基苄亚基樟脑、奥克立林、PABA乙基己酯、丁基甲氧基二苯酰基甲烷、甲氧基肉桂酸乙基己酯、水杨酸乙基己酯、胡莫柳酯等9种防晒剂的含量。样品用甲醇提取,以Ultimate XB-C18色谱柱为固定相,用甲醇和水以不同比例混合的溶液为流动相进行梯度洗脱,用二极管阵列检测器测定。9种防晒剂在一定的质量浓度范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在12.5~100mg·kg-1之间。以空白样品为基体进行加标回收试验,所得回收率在87.9%~95.7%之间,测定值的相对标准偏差(n=6)在3.4%~4.5%之间。     

Electrophoretically mediated microanalysis of beta-galactosidase on microchips.

Electrophoretically mediated microanalysis (EMMA) is a method of accomplishing chemical analyses, typically in an open-tubular capillary, due to the difference in the electrophoretic mobility between the particular reagents. This work reports on combining this technique onto microfabricated systems. Two methods of this technique were applied, constant potential and zero potential EMMA onto chips. A dosage response curve was run using this constant potential mode that resulted in a linear response over three orders of substrate concentration magnitude. The chemical system used here is beta-galactosidase (beta-Gal) as the enzyme and fluorescein mono-beta-D-galactopyranoside (FMG) as the substrate. The zero potential mode was used to amplify product turnover using various incubation times. Using this technique and a 10 min incubation, approximately 40000 enzyme molecules could be detected. The zero potential mode is also used in conjunction with an internal standard to show how one can quantitate using this method. The power and ease of utility of this technique is described.     

混合吸附剂在环境监测中分析苯系物的性能考察

探讨了单一吸附剂和混合吸附剂对大气中苯系物的回收率,同时对比了一些洗液,发现用二氯甲烷代替二硫化碳可取得更好的结果,因为前者不仅回收率高于后者,且更有利于减少环境污染。     

交联聚苯乙烯型多孔吸附剂的中孔性质研究

采用77K温度下的氮气吸附方法,测定了经悬浮聚合制备的不同交联度的交联聚苯乙烯多孔吸附剂的吸附/脱附等温线.根据BET吸附模型计算了比表面,由吸附量计算了总的孔体积,由孔体积和比表面计算出平均孔径,并依据脱附等温线采用BJH方法计算孔径分布.结果表明,交联度对交联聚苯乙烯多孔吸附剂的孔结构均具有显著影响.随着交联聚苯乙烯多孔吸附剂的交联度升高,其孔径变小,比表面增大,而且低交联度吸附剂的中孔接近圆柱形,高交联吸附剂的中孔形状接近“墨水瓶”形.显然,交联度对孔性质的影响与孔结构在交联聚苯乙烯多孔吸附剂制备和后处理过程中的稳定性密切相关.交联度低时,初期形成的小孔不能保持稳定,在后续聚合及后处理过程中合并为大孔,结果造成低交联吸附剂大孔径、低比表面的现象.通过对孔径分布的研究,揭示了不同吸附剂在中孔范围内的孔特征,并对其形成机制进行了分析.     

Secondary electron microanalysis

Secondary electron microanalysis is described as a nonconventional method to observe microareas at sample surfaces. The method is characterized by a high lateral and depth resolution and additionally by a typical sensitivity to localized electric potentials and electron work functions. The limits of the method for measurement at high vacuum conditions in conventional scanning electron microscopes are described in connection with electron-sample interactions. Examples for investigations of distributions of localized electric potentials, electron work functions at semiconductors, ferroelectrics and electric ceramics are given.     

Salt doping in electronprobe microanalysis

A new method of electronprobe microanalysis (EPMA) is suggested. It is based on creating ionic conductivity in frozen water solutions and in polymer films by doping them with a salt. This procedure is effective to prevent surface charging and allows imaging of nonconducting samples by scanning electron microscopy (SEM) as well as X-ray microanalysis. Specifically, this procedure makes it possible to perform EPMA of samples with xerogel matrices, which were used for molecular laser microprobe mass spectrometry analysis, and consequently to provide complex microprobe examination of samples. Received: 24 January 1996 / Revised: 4 July 1996 / Accepted: 16 July 1996     

Electrophoretically mediated microanalysis

This review describes the existing developments in the use of the capillary electrophoretic microanalytical technique for the in-line study of enzyme reaction, electrophoretically mediated microanalysis (EMMA). The article is divided into a number of parts. After an introduction, the different modes, basic principle, procedure, and some mathematical treatments of EMMA methodology are discussed and illustrated. The applications of EMMA for enzyme assay and for non-enzymatic determination are summarized into two tables. In addition to classical capillary electrophoresis (CE) instrument EMMA, special emphasis is given to a relatively new technique: EMMA on CE microchip. Finally, conclusions are drawn.     

Ultrastructure and microanalysis of silica bodies in Dactylis Glomerata L.

Silica bodies of orchard grass (Dactylis glomerata L.) were analysed by transmission electron microscopy and X-ray microanalysis. Silica bodies are inserted into the epidermis of the leaf and consist of a rather compact amorphous silica and low carbon. In particular regions of the interface between silica body and cell wall, silica is crossed by electron opaque strands, which are similar to filaments of the cell wall and most probably represent cellulose fibrils. The presence of a higher carbon content in this region than in the compact silica supports this notion. Cells with silicified walls or lumen were found apart from typical silica bodies. They most likely represent early or intermediate stages of silica body formation. Some epidermal cells showed silica deposits between protoplast and cell wall with small but regularly detected nitrogen and phosphorus peaks indicating a particular extracellular chemical composition probably involved in silica accumulation.     

Advances in capillary electrophoretically mediated microanalysis

Recent developments in the use of capillary electrophoretic techniques for the in-line study of enzyme reactions and derivatization protocols are reviewed. The article is divided into two parts: (i) in-line enzyme reactions and (ii) in-line derivatization. The first part introduces electrophoretically mediated microanalysis (EMMA) and discusses and illustrates the different modes of EMMA. A literature overview is provided, starting from 1996, and the investigated enzymes are classified into two tables based on the mode of engagement (i.e., continuous or transient) of the developed EMMA-based assay. The second part starts with an introduction of the procedures and the nomenclature used in the area of in-line derivatization protocols based on EMMA. Reported derivatization procedures are discussed and classified in tables, according to the functional group that is derivatized.     

Recent advances in electron-probe x-ray microanalysis

The review covers four main topics: analysis for light elements (Be-F); the use of digital x-ray mapping by wavelength-dispersive x-ray analysis; the use of software for automation of stage and beam control, selective feature analysis, spectrum processing and element identification by the use of expert systems; and the development of quantification models for bulk specimens.     

Nuclear microanalysis of titanium

Application of charged particle activation analysis (CPAA) for the detection of traces of titanium has been demonstrated. Experimental samples containing traces of titanium varying from ppm to ppb levels were prepared by coprecipitating it with aluminium hydroxide, subsequently converted to Al₂O₃. Titanium in Al₂O₃ were irradiated with 40 MeV -particles in the Variable Energy Cyclotron, Calcutta. The element was detected through the product radioisotopes,⁴⁸V,⁴⁷Ca,⁴⁷Sc,⁵¹Cr,⁴⁹Cr and⁴⁸Cr, produced from various nuclear reactions such as (, pxn), (, xn), etc. Suitability of Al₂O₃ as diluent matrix for the element has been verified.