Thermodynamics of partitioning of allyl isothiocyanate in oil/air, oil/water, and octanol/water systems

Polyparameter Linear Free Energy Relationships for Partitioning of Neutral Organic Compounds to Storage Lipids

Storage lipids are an important compartment in the bioaccumulation of neutral organic compounds. Reliable models for predicting storage lipid-water and storage lipid-air partition coefficients (Kislip/w and Kislip/a), as well as their temperature dependence, are considered useful. Polyparameter linear free energy relationships (PP-LFERs) are accurate, general, and mechanistically clear models for predicting partitioning-related physicochemical quantities. About a decade ago, PP-LFERs were calibrated for Kislip/w at the physiological temperature of 37 °C. However, to date, a comprehensive collection and sufficiently reliable PP-LFERs for Kislip/w and Kislip/a at the most common standard temperature of 25 °C are still lacking. In this study, experimentally based Kislip/w and/or Kislip/a values at 25 °C for 278 compounds were extensively collected or converted from the literature. Subsequently, PP-LFERs were calibrated for Kislip/w and Kislip/a at 25 °C, performing well over 10 orders of magnitude with root-mean-square errors of 0.17-0.21 log units for compounds with reliable descriptors. Furthermore, standard internal energy changes of transfer from water or air to storage lipids for 158 compounds were derived and used to calibrate PP-LFERs for estimating the temperature dependence of Kislip/w or Kislip/a. Additionally, using PP-LFERs, low-density polyethylene was confirmed to be a better storage lipid analogue than silicone and polyoxymethylene in the equilibrium passive sampling of nonpolar and H-bond acceptor polar compounds.

Colorimetry Technique as a Tool for Determining Release Kinetics and Mass Transfer Parameters of Anthocyanins Encapsulated in W1/O/W2 Double Emulsions

Anthocyanin extract (AE) was encapsulated in W1/O/W2 double emulsions and colorimetry technique using the CIE L*a*b* system was used to determine the release kinetics. Parameters a* and b* better correlated the variations in color of emulsions due to the release of AE into the external phase. Chroma value (C*) was used for tracking these color variations and to determine the release kinetics. The emulsions showed high stability, droplet sizes didn’t change after 30 days of storage (D4,3=4.74±0.12 μm), and 2.7 % AE was released to the external phase after this time. The possible release mechanism of AE from the internal phase of the emulsion is diffusion controlled with good accordance to Fick’s first law (R2=0.9938) with a diffusion coefficient of 7.15×10−8 cm2/d.