In a previous study,
it was observed that survivability was low
when attempting to cryopreserve sperm cells in a nanoliter-sized droplet
protected under soybean oil, in stark contrast to the high survival
rates in milliliter-sized droplets. In this study, infrared spectroscopy
was used to provide an estimate of the saturation concentration of
water in soybean oil. By following the time evolution of the infrared
absorption spectrum of water–oil mixtures, the saturation of
water in soybean oil was found to reach equilibrium after 1 h. From
the absorption spectra of neat water and neat soybean oil and the
application of the Beer–Lambert law to an estimation of the
absorption of a mixture from its individual components, it was estimated
that the saturation concentration of water is 0.010 M. This estimate
was supported by molecular modeling using the latest semiempirical
methods (in particular, GFN2-xTB). While for most applications the
very low solubility has little impact, the implications in those exceptions
were discussed.