Determination of total,and bound Se in sera by INAA

In this study we report on the comparison between the total selenium in serum (total Se) with that which is apparently bound to high molecular weight (>12,000 D) species, presumably proteins (bound Se). Nine hundred seventy seven (977) serum samples arising out of a population-based epidemiological study were prepared in duplicate for the determination of total Se by pipeting directly into irradiation vials; and separate duplicate aliquots were dialyzed against DI water for the determination of bound Se. All samples were analyzed by neutron activation analysis via^77mSe (17.4 s). A small dialyzable Se component (6%) (free Se), defined as the difference between the total Se minus the bound Se, was identified.     

Philosophical aspects of chemometrical strategy in Analytical Chemistry

Summary This paper discusses the philosophical aspects of the three main chemometrical strategies in analytical chemistry: statistical data treatment, optimization and modelling, pattern recognition. It is possible by a more general consideration of these approaches to find a proper place of different philosophical categories such as form and content, induction and deduction, concrete and general in analytical chemistry. The philosophical aspect of the considerations allows a deeper penetration into the theoretical basis of chemical analysis.

---

Philosophische Betrachtungen zu chemometrischen Strategien in der Analytischen Chemie

---

Presented at the First International Symposium on History and Philosophy in Analytical Chemistry, Vienna, November 22–23, 1985     

Multivariate Statistical Assessment of Air Quality: A Case Study

The present paper deals with the application of several chemometrical methods (cluster and principal components analysis, source apportioning on absolute principal components scores) to an aerosol data collection from Unterloibach, Austria. It is shown that seven latent factors explaining almost 80% of the total variance are responsible for the data structure and are conditionally identified as secondary aerosol, mineral dust, oil burning, lead smelter, coal burning, salt and fertilizer emission sources. Furthermore, the contribution of each identified source to the formation of the particle total mass and chemical compounds total concentration is calculated. Thus, a reliable assessment of the air quality in the region is performed. The requirements of the sustainability concept for ecological indicators in this case is easily transformed into a multivariate statistical problem taking into account not separate indicators but the specific multivariate nature of aerosol pollution.     

Natural flavours of wine: correlation between instrumental analysis and sensory perception

Summary The aroma of wine consists of 600 to 800 aroma compounds from which especially those, typical for the variety, are already present in the grapes. The aroma extracts — received by extraction with trichlorofluoromethane — are separated by gas chromatography. There are significant varietal differences between the aromagrams (fingerprint pattern). Thus the amount of some flavour compounds (key substances) shows typical dependence on the variety. Especially monoterpene compounds play an important role in the differentiation of wine varieties.The German white wines can be differentiated into three groups only by quantitative determination of 12 monoterpenes (terpene profile). These groups are: Riesling type, Muscat type and Silvaner-Weißburgunder type. Such terpene profiles are also useful for the separation of real Riesling wines from others called Riesling (e.g. Welschriesling, Kap Riesling, Emerald Riesling) but not produced from grapes of the variety Riesling. Including further components and by means of statistical methods as for example linear discriminant analysis even the different varieties within the mentioned groups (for instance the Riesling-group: Riesling, Kerner, Ehrenfelser, Bacchus, Müller-Thurgau) can be separated from each other.To identify compounds causing off-flavours the sniffing technique is the method of choice. The off-flavour is pinpointed during gas chromatography separation of the complex aroma mixture by effluent sniffing. Once allocated, the chemical nature of the off-flavours is elucidated by spectroscopic methods. Substances contributing to the green pepper taint, the strawberry note, mousiness, corkiness etc. in wine could be found in this way.     

Similarity and dissimilarity in posets

The relevance of partially ordered sets (or posets) in a wide diversity of contexts in chemistry is emphasized, and the utility of distance functions (or metrics) on such posets is noted. First a notion of scale similarity is introduced to make comparisons within certain so-called scaled posets, for which there is formulated natural comparators, which in turn lead to associated distance functions. Beyond taking note of several chemically relevant examples of these scaled posets and their consequent associated similarity measures, a second chemically relevant class of so-called shifted posets is similarly developed, with examples. Even further extension of some aspects of the current approach is indicated, and finally the multi-posetic character of chemical periodic law is suggested.     

Meeting the need for reference measurements

Summary Reference materials do fulfil a very useful function in that they provide means to check, verify and calibrate measurement procedures and instrumentation. However, the material is often idealized compared to real life samples: it is either (very) pure or does not correspond in concentration level or matrix to the real life case. It is shown how this situation could be remedied if real life samples with carefully assessed reference values could be made available regularly as unknowns to measurement laboratories. Comparison of the latter's measurements with the reference values then would provide a picture of the real performance of the particular measurement community in general and of each participating laboratory in particular. The opinion is expressed that isotope-specific methods have now matured to the stage that, if they are correctly applied under rigorous control and based on highly skilled expertise, they can provide such reference values against which laboratories can then evaluate their routine performance in regular Interlaboratory Measurement Evaluation Programmes (IMEPs).

---

Wie der Notwendigkeit von Referenzmessungen entsprochen werden kann

     

On the recognition of structural features: Some general problems illustrated by hamiltonian paths in polyhexes

Human and machine recognition skills are discussed, though not comprehensively reviewed, and some of the difficulties are illustrated by algorithms written to search for Hamiltonian paths in polyhexes. The most successful strategy for this is based upon the branching graph, a recently introduced graph-theoretical device which can aid the recognition of edges that arenot part of a Hamiltonian path. Another, more widely applicable approach that is interesting, although in this preliminary form only a little better than random methods, uses the metaphor of biological evolution, and tries to breed and grow paths subjected to natural selection.     

Understanding the properties of isospectral points and pairs in graphs: The concept of orthogonal relation

The mathematical property orthogonal relationship is used in proving the fact that isospectrality, isocodality and isocoefficiency of vertices within a graph are all equivalent. The same is true for isospectrality, strict isocodality and strict isocoefficiency of pairs (including edges) within a graph, whereas the weak versions of the latter properties are necessary but not sufficient for isospectrality of pairs. Similarly, necessary and sufficient conditions for isospectrality of vertices and pairs in different graphs are derived. In all these proofs, the concept of orthogonal relation plays a major role in that it allows the use of tools of elementary linear algebra.     

Interplay of Thermochemistry and Structural Chemistry,the Journal (Volume 13, 2002) and the Discipline

As practiced disciplines, structural chemistry and thermochemistry need not be related. In the current study they are: the contents of the journal Structural Chemistry (Vol. 13) for the year 2002 have been reviewed and then most articles that appeared therein were given a thermochemical commentary, spin or slant.     

Determination of polychlorobiphenyls and polycyclic aromatic hydrocarbons in the atmospheric aerosol of the Venice Lagoon

An analytical method for simultaneous determination of particle-associated and gaseous-phase concentrations of polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) in atmospheric aerosol samples obtained by high-volume samplers using polyurethane foam adsorbent (PUF) and quartz fibber filters (QFF) has been investigated. Quality control of the analytical procedure was carried out by blank control and by evaluating limits of detection, recoveries, accuracy, and repeatability. The proposed method was subsequently used to determine PAH and PCB in the gaseous and particulate phases of the aerosols that enter the Venice Lagoon atmosphere. The highest concentrations of PCB and PAH were predominantly in the gaseous phase. In both particulate and gaseous phases the penta-CB congeners dominated total PCB concentrations whereas phenanthrene, fluoranthene, and pyrene dominated the PAH concentrations. Total (gaseous plus particulate) PCB and PAH concentrations were higher at the site directly influenced by the industrial plants but the concentrations in marine aerosol samples were lower by a factor four only and must be taken into consideration when studying the chemical contamination of the Venice Lagoon.     

A software package for the evaluation of Zeeman AAS data using a Perkin-Elmer model 3600 data station

The Perkin-Elmer Zeeman/5000 Atomic Absorption Spectrometer is only able to perform a calibration with three single standards or a one-point standard addition. The accuracy and precision of these methods are inappropriate in ETA-AAS, a computer-based data management is essential.A software package for calibration and evaluation was developed using curve fitting by linear regression based on a leastsquares fit when absorbances were transformed by the Baule-Mitscherlich function. The total analytical range could be covered by this method whether peak area or peak height values were fitted. The maximum absorbance levels could be calculated, as well.Absorbance signals were collected and stored by the HGA-graphics software (modified by Perkin-Elmer Nederland B. V.). The Pecowriter software was used for identifying data and file manipulations. The results of the calibration and evaluation can be stored on disk and/or printed. Calibration curves can be plotted on hardcopy output. The Limit of Detection and the Characteristic Mass can be calculated.The use of the CALIBRATION program is demonstrated by the calibration curves for the determination of Pb, Cd, As, Se, Cr, Al, Cu and Ni using mostly STPF-conditions. The performance of the method evaluated by the root mean square percent deviation of the fit is equal to the traditional curve-fitting function as well as to rational or quadratic functions.The use of the EVALUATION program is demonstrated by the results of the direct determination of lead in mineral waters.     

Theoretical am1 studies of inclusion complexes of α- and β-cyclodextrins with methylated benzoic acids and phenol,and γ-cyclodextrin with buckminsterfullerene

Semiempirical AM1 calculations have been performed on the inclusion complexes of - and -cyclodextrin with benzoic acid and phenol and -cyclodextrin with methylated benzoic acids in the head first and tail first positions. The results show that -cyclodextrin complexes with phenol and benzoic acid guests in the head first position are more stable than in the tail first position, while -cyclodextrin complexes with the same guests prefer the tail first position. The preferred orientation for -cyclodextrin with methylated benzoic acids is determined by the position of the methyl substituent(s). In general, para-methyl benzoic acid derivatives prefer the tail first position. -cyclodextrin forms a slightly unstable 1:1 complex with C₆₀ (3.4 kcal/mol), but two -cyclodextrins provide enough stabilization by about 10 kcal/mol to cage-in the C₆₀.     

A Note on Distance Matrices Yielding Elementary Landscapes for the TSP

Symmetric and antisymmetric distance matrices in the single agent traveling salesman problem (TSP) are not the only distance matrices to generate elementary landscapes for swap and 2-opt neighborhoods.     

To the Theory of the Aggregation of Polydisperse Colloids

Particle aggregation in polydisperse colloids is studied theoretically. It is assumed that the aggregation follows phase transition scenario with the formation of dense uniform colloidal phases. Bidisperse model corresponding to the system of relatively large and small particles is considered. Van der Waals attraction between large particles and the action of relevant entropy forces due to the presence of depleted layers of small particles are taken into account. The diagrams of equilibrium phase transitions of gas–liquid and gas–solid types occurring in the ensemble of large particles are constructed. The influence of size and concentration of small particles on the pattern and structure of phase diagrams is studied. It is shown that an increase in the concentration of small particles leads, on the one hand, to a rise of phase transition temperature and, on the other hand, to an increase in the threshold concentration of large particles.     

Zur Literaturdokumentation in der Analytischen Chemie

Zusammenfassung Anhand von 298 Referaten aus Fresenius Z. Anal. Chem. werden systematisch geordnete Listen von Indexbegriffen für die Bereiche Methoden und Anwendungen erstellt und auf diese Referate angewendet. Diese vorläufige Systematik umfaßt 63 und 32 Hauptindexwörter. Den dokumentierten Referaten wurden 815 Schlüsselwörter (Hauptindexwörter) zugeordnet (116 Referate mit 2, 134 Referate mit 3 Hauptindexwörtern, Minimum: 1, Maximum: 5). Für zwei Indexabschnitte, Atomabsorptionsspektrometrie und Geologisches Material, wird die vorgeschlagene Indexierung vorgestellt und mit der bisherigen in Fresenius Z. Anal. Chem. verglichen. Die überschaubare Zahl von 95 Hauptindexwörtern, die erkennbare, einfache Systematik und die Wahlmöglichkeiten von zusätzlichen Nebenindexwörtern sollen zu einer benutzerfreundlichen Dokumentation beitragen, welche hiermit zur Diskussion gestellt wird.

---

Literature documentation in analytical chemistryIV. Development of a systematic, easily usable index and documentation system

Summary By means of 298 abstracts from Fresenius Z. Anal. Chem. systematically arranged lists of index terms for the fields methods and applications were compiled and used for these abstracts. This preliminary system contains 63 and 32 first index terms. 815 Key words were allocated to the abstracts (= first index terms): 116 abstracts with 2, 134 abstracts with 3 first index terms, minimum: 1, maximum: 5. For two index sections, l.e. atomic absorption spectrometry and geological materials, the proposed indexing system is presented and compared with the system hitherto used in Fresenius Z. Anal. Chem.. The favourable number of 95 first index words, the obviously simple system and the possibility of selecting additional second index terms should contribute to an easily usable documentation, which is herewith presented for discussion.

---

---

Teil III: Fresenius Z Anal Chem (1982) 312:448–454     

Electrochemical dissolution of magnetite in acid solutions

The present paper deals with the electrochemical behavior of magnetite microcrystals in an acid medium. A voltammetric method employing a carbon-paste electroactive electrode (CPEE) with an organic binder was used. It was found that the cathodic voltammograms, which were recorded at different scan rates, formed a set bounded in the space of i–E parameters by a generalizing voltammetric curve corresponding to the effective potential scan rate _eff. In other words, all curves are situated under one enveloping curve, just as the smaller dolls sit in the largest doll of a Russian doll. Reverse currents (a cathodic current in the anodic direction of the potential scan) were observed on the cyclic voltammogram. Forward and reverse currents obey the same laws and have one and the same generalizing curve, which could be taken as the magnetite characteristic.     

Formation mechanism of anomalous “golf ball-like” composite polymer particles by seeded emulsion polymerization

Recently, the authors found that anomalous polystyrene/polybutyl acrylate composite particles, whose surfaces had many dents, were produced by emulsifier-free seeded emulsion polymerization of butyl acrylate with polystyrene seed particles. Such a particle was named a golf ball-like particle. In this article, the morphology and the formation mechanism of the golf ball-like composite polymer particles were studied.Part CLV of the series Studies on Suspension and Emulsion     

Zur Bildung der „roten Kohle”

Zusammenfassung Es wird die Induktionsphase bei der sogenannten Polymerisation von Kohlensuboxid zur roten Kohle sowie die rote Kohle selbst IR- bzw. UV-spektroskopisch untersucht. Dabei werden Ketencarbonsäure bzw. deren Derivate und Acetondicarbonsäureanhydrid (=3-Oxoglutarsäure-anhydrid) als Polymerisationsstarter nachgewiesen und eine Polypyronostruktur der Polymeren—im Gegensatz zu den Arbeiten vonDiels ¹ undWojtczak et al.²—bestätigt.

---

Formation of red coal

The induction phase of carbon suboxide polymerization to red coal has been investigated by IR-and UV-spectroscopy. It is shown that ketene carboxylic acid, or its derivatives, and 3-oxoglutaric anhydride are the polymerization initiators, and that the polymer has a polypyrone structure. This latter finding conflicts with results obtained byDiels ¹ andWojtczak ².

---

---

Herrn Prof. Dr.R. Tschesche, Bonn, zum 65 Geburtstag gewidmet.     

The structures of macrocyclic heterocyclophane inclusion complexes

Crystal and molecular structures of (1:1) molecular complexes of N,N,N,N-tetramethyl-2, 11, 20, 29-tetraaza [3.3.3.3] paracyclophane (1) with CHCl₃, CH₂Cl₂, CH₃CN and CO₂ are reported. The macrocycle has square-box structure, giving hydrophobic cavity surrounded by four benzene rings. The guest molecules are included in the cavity. The uncomplexed1 was found to have a rectangular form, indicating large conformational flexibility of1. In solution,1 is achiral because rapid RS interconversion, but in solid, the macrocyclic conformation is frozen as R-conformer or S-conformer. The macrocycles with the same chirality are stacked alongb-axis to form chiral molecular columns, R-colums or S-columns. Complexes of1 crystallize differently depending on the guest molecules. R-columns (S-columns) packed alonga-axis produce R-layers (S-layers), which are further packed alongc-axis using R-layer to R-layer contact (RR) or SS and RS or SR. The crystals of1·CHCl₃ are formulated as--RRR--=[R]_n (Type I, chiral) and those of1·CH₃CN or1·CO₂ and1·CH₂Cl₂ are represented by [RS]_n (Type IIA, racemic) and [RRSS]_n (Type IIB, racemic), respectively.     

Meeting future needs for metrological traceability—a physicist’s view

Abstract Metrological traceability of measurement results provides the comparability needed for reliable measurement in almost every aspect of our daily life, ranging from fundamental science, through health and safety to global trade. From the authors (a physicist) perspective and understanding of recent literature, measurements in chemistry compare the amount of analyte, are often made indirectly, are sometimes not fully traceable to the SI, and metrological traceability is perhaps not always the major concern of the practising analytical chemist. The present article examines which of these views are typically chemical, and which are common to both the physicist and the chemist. Much can be gained by formulating a common understanding of basic concepts of traceability of measurement results in meeting ever-increasing demands for comparability of measurement results in both traditional as well as new areas of technology and societal concern.Based on a lecture given by the author at a mini-symposium Emerging issues in metrology in chemistry organised by the IUPAC Analytical Chemistry Division and IUPAC Working Party for Harmonisation of Quality Assurance at IAEA Headquarters, Vienna, 17th February 2004.