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Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed.

The characterization of ink on paper is of importance for dating and comparing questioned ink entries in forensic document examination. Inks are commonly characterized by their colorant profile that is identified by well-established analytical methods. Numerous ink formulations show identical colorant profiles, though. In order to differentiate inks that are not distinguishable by colorant analysis, a method for the characterization of colorless ink ingredients, namely binders, solvents and additives is necessary. In this paper, we propose a technique for the analysis of colorless compounds in ballpoint inks using direct thermal desorption of the ink on paper followed by chemical analysis of the desorbed volatile compounds by gas chromatography-mass spectrometry. As compared to liquid extraction and subsequent analysis of the extracts, the technique avoids possible contamination risks. Sensitivity is very high due to the enrichment of volatile components by thermal desorption. Even from old samples, the chromatograms obtained by the method enable the determination of binder polymers, solvents and additives. Pure binders as used by ink manufacturers were analyzed for unambiguous assignment of analytical results to specific polymers. To prove the practical applicability, we analyzed 121 ballpoint pens, not all having the same colorant profile, and grouped the pens into resin and solvent categories.

The characterization of ink on paper is of importance for dating and comparing questioned ink entries in forensic document examination. Inks are commonly characterized by their colorant profile that is identified by well-established analytical methods. Numerous ink formulations show identical colorant profiles, though. In order to differentiate inks that are not distinguishable by colorant analysis, a method for the characterization of colorless ink ingredients, namely binders, solvents and additives is necessary. In this paper, we propose a technique for the analysis of colorless compounds in ballpoint inks using direct thermal desorption of the ink on paper followed by chemical analysis of the desorbed volatile compounds by gas chromatography-mass spectrometry. As compared to liquid extraction and subsequent analysis of the extracts, the technique avoids possible contamination risks. Sensitivity is very high due to the enrichment of volatile components by thermal desorption. Even from old samples, the chromatograms obtained by the method enable the determination of binder polymers, solvents and additives. Pure binders as used by ink manufacturers were analyzed for unambiguous assignment of analytical results to specific polymers. To prove the practical applicability, we analyzed 121 ballpoint pens, not all having the same colorant profile, and grouped the pens into resin and solvent categories.

Differentiation and classification of ink entries with dated samples of a reference collection are important aspects in the examination of questioned documents. Classification of writing inks is presently achieved by analysis of dyes and colorants contained in the ink. This technique has its limitations in newly developed ink formulations with identical dye composition but differing in their solvents and binder resins. This paper introduces a method for the determination of solvents and binder resins of an ink sample directly from paper without sample preparation. This aim is accomplished by thermodesorption of the sample followed by gas chromatography/mass spectroscopy. The method was tested on numerous samples of ballpoint pen inks, which were subsequently grouped into several solvent and resin subgroups. A case study shows the applicability of the newly developed method.

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The enantiomers (M) and (P) of helical 9, 10-phenanthrenequinones were enriched by liquid chromatography with enantiomeric purities of 0.31 to 0.95. Their barriers to racemization (Table 2) were compared with the ones of the corresponding hydrocarbons.

A series of phenanthrenesemiquinone–diphenylthallium complexes were prepared in solution from the corresponding quinones. ESR, ENDOR and TRIPLE spectra provided the proton coupling constants and the unambiguous assignment to distinct molecular positions. The thallium splitting becomes considerably less negative if the semiquinones are twisted by steric hindrance in the 4- and 5-positions. On the other hand, substitution in the 1- and 8-positions renders aTI more negative. These results are interpreted in terms of steric hindrance of the ion-pair solvation.

Polarimetric and/or circular dichroic detection of enantiomers after liquid chromatography on optically active sorberts has been used for the following purposes: determination of enantiomeric purity in spite of peak overlap, investigation of enantiomerization during chromatography, monitoring of racemizations and recording of circular dichrograms without preparative enrichment of enantiomers. Novel examples for all applications are give. The general prospects for chiroptical detection are discussed.

Die SuszeptibilitAt einiger organischer Substanzen wird untersucht; diese bleibt unverAndert, wenn schwache Au\ere Einflusse, wie Mischung mit anderen Substanzen, Kristallwasser und Ahnliches einwirken.

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Mit Hilfe der Verpflanzung aus dem Teich in Laboratoriumsbedingungen konnen amiktisch sich vermehrende Weibchen einer heterogonen Radertierart zur Erzeugung miktischer Tochter gezwungen werden. Der Milieuwechsel kann die Fortpflanzungsart der bereits aus dem Ei geschlupften Weibchen nicht mehr verandern. Er ist auch wirkungslos, wenn er Eier trifft, welche aus dem Geschlechtsapparat der Mutter bereits ausgetreten sind oder kurz davor stehen. Die Determination der Fortpflanzungsart erfolgt auf einem fruheren Entwicklungsstadium des Eies. Die Resultate stimmen bei allen gepruften Arten uberein.

Fur die Beurteilung der Bruchgefahr und der Verwendbarkeit eines Werkstoffes bei Dauerbeanspruchung ist die Kenntnis der Ermuauni serscheinungen, der Zerruttung des Werkstoffes bei Wechselbelastung notwendig. Als Beitrag zur Klarung dieser Frage wird die Veranderung der Elastizitatsgrenze von Stahlen bei wechselnder Belastung untersucht. Die Werkstoffgrosen Fliesgrenze, Dauerfestigkeit, Werkstoffdampfung, Kerbempfindlichkeit werden mit dem Verhalten der Eiastizitatsgrenze in Zusammenhang gebracht. Aus der Veranderung der Elastizitatsgrenze wird ein Kurzverfahren zur Bestimmung der Schwingungsfestigkeit von Stahlen entwickelt. Weiterhin ergibt sich eine Werkstoffkonstante fur die Grose des Abbaues von Spannungsspitzen.

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The males of Asplanchna sieboldi, which have neither mouth nor anus, possess an organ consisting of several vesicles. It is homologous to the female digestive tract and serves as an energy storage organ. In new-born males it is filled with glycogen, which is used up during their 3–5 day life-span.

WITH regard to the discussion in NATURE by Trew and Spencer1 and Ranganadham2 on the diamagnetism of liquid mixtures, I should like to communicate the following data based on measurements carried out by me.

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