ii few smaller peptlaes n o t recovered from t h e lnltlai dlgrSt.

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Environmental analysis needs quantitative determinations and identification at concentration levels which are out of reach of most direct working analytical systems. Ethylene in air, a very active hormone for plants, kills some flowers within 24 hours when its concentration level reaches 10~7% (v/v). Many other reactions of ethylene with plants have been reported by D. Zimmerman (1), H. O. Kunkel (2), and F. B. Abeles (3), showing that ethylene in air has to be controlled to well under its lethal dose of 10~7% (v/v) for plants.Even at a distance of 15 miles from a chemical factory, ethylene emission can reach levels higher than 10_5% (w/w). This is only one example where specific analysis in environmental control is necessary by specific enrichment, separation, and detection of a single compound.

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Key Words:Gas chromatography Capillary, glass SECAT-technique = stepless fine tuning of capillary Exponential influence of temperature on selectivity over a SECAT-technique ready for automation of column adjustment Instrumental and methodological details for primitive self selectivity by serial column temperature optimization wide range found on sample composition polarity made solution given Summary GC, including capillary GC, is rather inflexible, if a certain column length and stationary phase has been fixed for a given analytical problem. If the sample composition changes, one often has to change the column length and/or stationary phase, at least when something like optimum analytical conditions are needed. Temperature changes (or heating rates) can change the selectivity of a given column only within very limited ranges, due to the exponential effect of temperature on retention time. By serial coupling two chemically different capillaries, each run at another temperature, even the slightest changes of these two temperature values have a dramatic effect on the selectivity of the system for polar substances. We call this technique the SECAT mode of GC. Results are reported as retention index shifts, dependent on SECAT temperature data. This technique can in future easily be automated, thus enabling the analyst, for polar sample analysis, to adjust a given chromatographic system to his specific sample composition without touching the instrument.

ZUSAMMENFASSUNG :Bei der thermischen Polymerisation von Styrol entstehen in einer Nebenreaktion gesiittigte und ungesiittigte Oligomere, die nach MAYO in engem Zwmmenhang mit der Startreaktion stehen.Durch unabhiingige Synthese der Dimeren konnten wir die kiirzlich von BROWN verdffentlichten Strukturen bestiitigen. Hauptkomponenten der Dimerenfraktion sind trans-und cis-1.2-Diphenylcyclobutan im Verhiiltnis etwa 3: 1 ; in kleineren Mengen wurden noch 1.3-Diphenylbuten-3 und 1-Phenyltetralin nachgewiesen.Hauptaufgabe dieser Arbeit war die Strukturaufkliirung der trimeren Styrole. Das Auftreten von 1.3.5-Triphenylhexen-5 konnte durch Synthese gesichert werden; es ist zu etwa 30% in der Trimerenfraktion enthalten. Weiterhin konnten wir zeigen, daB etwa 65 yo der Trimerenfraktion aus den vier isomeren, optisch inaktiven 1 -Phenyl-4-[l'-phenyliithyl-( 1')]-1.2.3.4-tetrahydronaphthalinen bestehen. Die Struktur wurde durch Dehydrierung zum optisch inaktiven l-Phenyl-4-[l'-phenyliithyl-(1')l-naphthalin und dessen Vergleich mit einer unabhiingig synthetisierten Probe bewiesen. SUMMARY :Saturated and unsaturated oligomers are formed by a side reaction during the thermal polymerization of styrene. MAYO haa suggested that these oligomers are closely associated with the initiation step.Recently the structures of the dimer fraction were published by BROWN. By independent synthesis of the dimers we could confirm his results. The main components of the dimer fraction are trans-and cis-1.2-diphenylcyclobutane in a ratio of 3: 1 ; also smaller amounts of 1.3-diphenylbutene-(3) and 1-phenyltetralin were found.The aim of this work was to clarify the structures of the trimers. The trimer fraction contains about 30% of 1.3.5-triphenylhexene-(5), the structure of which

We describe the polarity of selectivity of a GC separation system in terms of Retention Index data. In a series-coupled capillary system having stationary phases of differing polarity even slight (independent!) carrier gas flow changes in one part of the capillary series result in a dramatic change of selectivity. "Dramatic" is a relative term! Using a simple electronically controlled flow changing device we found retention index changes of several hundred units for polar test compounds such as phenols on a SESOKarbowax tandem. This means: The classical theoretical model for understanding retention (and selectivity) in chromatography must be corrected. We propose a very simple approach involving addition of the expression RESIDENCE TIME to the chromatographic vocabulary. Instead of using flow resistors, one can just add a pressure regulator to the coupling point. A powerful analytical concept is now in easy reach.