Education in analytical chemistry in the U.S.S.R.

Analytical Chemistry is taught at over 600 schools of higher education in the U.S.S.R. Contents of general and special courses are described in this article. The main problems and objectives of education at universities are mentioned.     

The detection of nicotine in a Late Mayan period flask by gas chromatography and liquid chromatography mass spectrometry methods

Several ancient Mayan vessels from the Kislak Collection of the US Library of Congress were examined for the presence of alkaloids. One of them, a codex‐style flask, bears a text that appears to read yo‐'OTOT‐ti 'u‐MAY, spelling y‐otoot 'u‐may 'the home of its/his/her tobacco'. Samples extracted from this Late Classic period (600 to 900 AD) container were analyzed by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) methods. Nicotine was identified as the major component of the extracts. LC/MS analyses also yielded signals due to nicotine mono‐oxides. The identities of the compounds were determined by comparison of the chromatographic and/or mass spectral characteristics with those from standards and literature data. High‐resolution high mass accuracy tandem mass spectrometry (MS/MS) spectra of protonated nicotine and nicotine mono‐oxides were measured to verify and to correct previous product ion assignments. These analyses provided positive evidence for nicotine from a Mayan vessel, indicating it as a likely holder of tobacco leafs. The result of this investigation is the first physical evidence of tobacco from a Mayan container, and only the second example where the vessel content recorded in a Mayan hieroglyphic text has been confirmed directly by chromatography/mass spectrometry trace analysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Paul Schuftan and the early development of gas-adsorption chromatography

The life and activities of Paul Schuftan, a pioneer in gas-adsorption chromatography are discussed and placed in the context of the early evolution of gas chromatography.     

The early development and rapid growth of gas chromatographic instrumentation in the United States

The role of the American instrument companies involved in the development and manufacturing of gas chromatographic (GC) instruments up to about 1962 is reviewed. In addition, the origin of some supply houses is discussed and the role of the instrument companies in the dissemination of technical information is emphasized. Finally, some data are given on the worldwide GC market, and its expected evolution in the near future is outlined.     

Hold-up time in gas chromatography. V. Dependence of the retention of n-alkanes on the chromatographic variables in isothermal gas chromatography

The chromatographic behaviour of n-alkanes and other homologous series in isothermal gas chromatography has been shown to depart from the "linear" representation of the logarithms of the adjusted retention times vs. carbon number. One of the expressions proposed to describe this behaviour is tR(z)=A+exp(B+CzD). In this paper, a regression analysis shows that three of the parameters of the equation depend on different chromatographic variables such as hold-up time, average linear gas velocity, volume and polarity of the stationary phase and temperature of the column. The fourth parameter (D), responsible for the departure from the "linearity", does not depend on any chromatographic variable, and represents a gradual decrease of the contribution of the methylene groups to the general properties of n-alkanes, with no relation to the chromatographic phenomenon.     

Polymer battery R&D in the U.S.

Polymer electrolytes that have been developed for battery applications fall into two general classes, neat or “pure” polymer and plasticized or gel in which the polymer is combined with a conducting organic electrolyte. The polyethylene oxide (PEO) and its modifications are typical of the “pure” polymer electrolytes. They have poor conductivity at room temperatures, but at elevated temperatures, their conductivity is of the order of 10⁻³ to 10⁻⁴ S/cm. The PEO electrolytes have found application in the high temperature (>60°C) lithium metal anode battery systems. The high temperature necessary for good operation makes them unsuitable for use in small consumer appliances. The polymer electrolyte battery development activities have resulted in several high performance battery systems now just entering the market. Not all of the developments have resulted in commercial cell production. The commercialization activities of high performance lithium‐ion (Li‐Ion) batteries have been based on two general plastic polymer systems: poly‐vinylidene difluoride‐hexafluoropropylene copolymer (PVdF‐HFP) and polyacrylates. The polymer cells are expected to have advantages in manufacturing, flexibility, thin cell formats and lightweight packaging. Important parameters in PVdF gel electrolyte performance include the electrolyte type (combination of organic carbonates), temperature, and HFP copolymer content. Li‐Ion coin cells fabricated with a polyolefin separator with either liquid electrolyte or with the PVdF gel polymer electrolyte have equivalent performance.     

The overload phenomenon in gas chromatography

The usual concepts of the dynamics of an overloaded solute band fail to explain several phenomena such as the typical “leading-tail” shape and retention deviations exhibited by overloaded peaks, and why these defects are more commonly observed in short columns. These and other related deviations from theory can be rationalized by a non-classical approach to the overloading phenomenon.     

The acid-base properties of solochrome violet R. S.

Summary The acid base properties of solochrome violet R.S. has been studied with the object of testing its use as an acid base indicator or as a colorimetric reagent. The pk values of 4.35, 7.4, and 9.45 corresponding to the three steps of ionisation of the free acid were evaluated by the aid of the relation between log (acid)/(salt) and ph values obtained during the course of the potentiometric titration of the free acid with a free base. The dye has proved to be a suitable indicator in titrating some mineral and organic acids as well as a colorimetric reagent for the microdetermination of vanadium.     

Metabolic fingerprinting investigation of Artemisia annua L. in different stages of development by gas chromatography and gas chromatography-mass spectrometry

Artemisia annua L. is an annual herb native of Asia and this plant has been famous for the discovery of the anti-malarial drug artemisinin since 1971. In this work, to investigate variety of whole metabolites, metabolic fingerprinting analysis of A. annua L. was carried out by GC and GC-MS coupled with trimethylsilyl derivatisation. Principal component analysis and partial least squares discriminant analysis were employed to classify GC data of A. annua L. samples at five developmental stages. The results indicated that there was no distinct difference of metabolites between control (001) and transgenic strain (F4) from the tender seedling stage to adult seedling stage, but clear differences were detected at pre-flower budding stage, flower budding stage and full flowering stage. Three precursors of artemisinin biosynthesis were studied at five developmental stages and found that a possible bottleneck exists in the conversion from artemisinic acid or dihydroartemisinic acid to artemisinin.     

Simultaneous C-H-N and S microdetermination by combustion and gas chromatography

Summary A method based on flash-combustion of the sample in a flow of temporarely oxygen-enriched helium, catalytic oxidation and reduction of the combustion gases within the same reactor, gas-chrom- matographic separation and thermal-conductivity detection of the end-products, has been developed in order to determine C-H-N-S simultaneously in organic and inorganic substances, with a 0.1–2 mg sample. To develop this method, optimization of analytical parameters was necessary because of the chemical and physical behaviour of oxides of sulphur in the analyser. Therefore flashcombustion in a tin container, use of a tungstic oxide oxidative layer close to a copper reductive layer, setting the copper temperature at 850° C and selective halogen adsorption are the main features. The temperature of 850° C for the copper gives a quantitative yield of SO₂ in spite of the reaction between sulphur oxides and cupric oxide, and also gives quantitative reduction of the nitrogen oxides. The individual components of the combustion mixture are separated by means of a Porapak QS column and detected in the sequence Na, CO₂, H₂O and SO₂, the signals being automatically integrated and printed. Detector response for SO₂ is linear from someg up to 10 mg.

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Zusammenfassung Zur gleichzeitigen Bestimmung von C, H, N und S in 0,1 bis 2 mg anorganischer oder organischer Substanz wurde ein Verfahren entwickelt, wobei die Substanz in zeitweilig sauerstoff-angereichertem Helium verbrannt, die Verbrennungsprodukte im selben Reaktionsrohr zunächst katalytisch oxydiert, dann reduziert werden. Anschließend werden die Endprodukte gas-chromatographisch getrennt und mittels Wärmeleitfähigkeitsmessung bestimmt. Zur Entwicklung dieses Verfahrens mußten die analytischen Parameter wegen des chemischen und physikalischen Verhaltens der Schwefeloxide optimiert werden. Daher werden Flammenverbrennung in einem Zinngefäß, Verwendung von Wolframoxid als oxydierende Schicht unmittelbar neben Kupfer als reduzierender Schicht, die auf 850° C gehalten wird, sowie selektive Adsorption der Halogene als wichtigste Schritte betrachtet. Die Temperatur von 850° C gewährleistet quantitative Ausbeute an SO₂ im Gegensatz zur Reaktion zwischen Schwefeloxiden und Kupferoxid und führt auch zur quantitativen Reduktion der Stickstoffoxide. Die einzelnen Teile des Verbrennungsgemisches werden mit einer Säule aus Porapak QS getrennt und in der Reihenfolge N₂, CO₂, H₂O und SO₂ nachgewiesen, wobei die Signale automatisch integriert und gedruckt werden. Der Detektorausschlag für SO₂ ist von einigen Mikrogramm bis 10 mg linear.

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Dedicated to Prof. H. Lieb for his 90th birthday.

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Presented at the International Symposium on Microchemical Techniques, May 23–27, 1977, Davos, Switzerland.