Chemistry Reference
In-Depth Information
Correlation studies of mass spectral patterns and
elasticity of sea-slick materials
Nelson M. Frew, Robert K. Nelson and Carl G. Johnson
Department of Marine Chemistry and Geochemistry, Woods Hole
Oceanographic Institution, Woods Hole, USA
Abstract.
Variations in the chemical composition of surfactants from natu-
ral sea slicks are compared to variations in surface elasticity using mass
spectrometry, Langmuir film balance measurements, and multivariate sta-
tistical techniques. It is shown that the information on chemical class and
molecular structure contained in the mass spectra is strongly correlated
with measured static elasticity and can be used to estimate film elasticity at
a given surface pressure.
1. Introduction
The surface physical properties of a surfactant are strongly dependent on
molecular structure (Gaines 1966). As multicomponent systems, micro-
layer films exhibit a more complex rheological response to surface strain-
ing than monolayers of single pure compounds (Bock and Frew 1993).
Since the composition of these mixed films is too complex to allow rigo-
rous modelling of surface rheology based on individual component proper-
ties, an empirical approach is suggested. The mass spectral fingerprints of
sea-slick materials may contain information not only about chemical com-
position and molecular structure, but also the surface elasticity. Thus, it
may be possible to use the mass spectra of microlayer organics not only to
identify the structural classes that control elasticity but also to predict elas-
ticity. We explore this hypothesis by applying chemometric techniques to
the mass spectra. We show, through the use of multivariate analysis, the
effect of these compositional variations on the film elasticity.
