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Generally, surfactants contain trace impurities that will falsify their adsorption properties enormously. To carry out reliable experiments with surfactant solutions necessitates removing those trace impurities beforehand. A programmed apparatus for removing surface-active trace impurities from surfactant solutions has been constructed and tested. It takes advantage of the contaminants’ stronger surface activity and considerably lower content in comparison with the main surfactant component. Surface-active material of the solution to be purified is allowed to adsorb at its surface. After considerable reduction of the solution surface area, the adsorbed material is sucked off from the surface in a definite manner by using a fine capillary. The single operating steps are repeated periodically and automatically until the solution reaches the state of ‘‘surface chemical purity.’’ The apparatus can be utilized for a wide range of different conditions given by the individual surfactant properties simply by changing the operating parameters. The instrument favorably and effectively provides that peculiar grade of surfactant purity necessary for all kinds of fundamental surfactant research and characterization.

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The potential of vibrational spectroscopy methods (attenuated total reflectance/Fourier-transform-infrared (ATR/FT-IR), FT-Raman and near infrared (NIR) spectroscopy) for the identification and quantification of valuable as well as carcinogenic substances in different basil chemotypes is described. It is shown that all main volatile components occurring in different basil accessions can be reliably determined in the isolated essential oils or solvent extracts but also in the air-dried herbs. While NIR data can be interpreted only by chemometric methods, IR and Raman spectra present characteristic key bands of the individual volatiles; therefore, in the latter case, a discrimination of basil chemotypes is frequently possible without applying chemometric algorithms. NIR calibrations are successfully established for various terpenoids and phenylpropanoids; on the basis of these data, the content of the two carcinogenic compounds methyleugenol (range: 2-235 microg/100 g) and estragole (range: 34-138 microg/100 g) can be reliably predicted in air-dried basil leaves (R (2) (coefficient of determination) = 0.951; SECV (standard error of cross validation) = 19.1 microg/100 g and R (2) = 0.890; SECV = 12.8 microg/100 g, respectively). The described methods were found to be very useful tools for the efficient selection of special basil single plants, adapted to the new demands set by the legislator and the consumer. Furthermore, they can be applied in industry to very easily control the purifying, blending, and redistilling processes of basil oil.

Fourier transformed-Raman (FT-Raman) and attenuated total reflection-infrared (ATR-IR) spectra of essential oils obtained from marjoram and oregano plants by hydrodistillation are presented. It is shown that the main components of the essential oils can be ascertained through both of these complementary techniques, using spectral information from the pure terpenoids. Spectroscopic analysis is based on the characteristic key bands of the individual volatile substances and therefore, in principle, these techniques allow us to discriminate between different essential oil profiles from individual oil plants of the same species (chemotypes). The combination of vibrational spectroscopy and hierarchical cluster analysis provides a fast, easy and reliable method for chemotaxonomy characterisation. The spectroscopic data presented here correlate very well with those found by gas chromatography (GC) analysis.