MODELING PLANT UPTAKE OF AIRBORNE ORGANIC-CHEMICALS .1. PLANT CUTICLE WATER PARTITIONING AND MOLECULAR CONNECTIVITY

Molecular connectivity indexes were tested with regard to their ability to describe the cuticle/water partitioning for a variety of organic chemicals. A model is derived that accounts for 99% of the variation in the published cuticle/water partition coefficients (K(CW)), which cover the range of 8.5 orders of magnitude. It is shown that the molecular size is directly proportional to the cuticle/water partition coefficients. It is also the most important structural feature that accounts for 89% of the variation in the measured K(CW) data. Moreover, the molecular connectivity model outperforms in accuracy and speed the traditional empirical models based on 1-octanol/water partition coefficients or water solubilities. Our results and their comparison with previously published models demonstrate that the molecular connectivity model is an accurate predictive tool for the cuticle/water partition coefficients of a wide range of commercial chemicals and that it can be confidently used to assess their potential to penetrate and to accumulate in aboveground vegetation.; Molecular connectivity indexes were tested with regard to their ability to describe the cuticle/water partitioning for a variety of organic chemicals. A model is derived that accounts for 99% of the variation in the published cuticle/water partition coefficients (KCW), which cover the range of 8.5 orders of magnitude. It is shown that the molecular size is directly proportional to the cuticle/water partition coefficients. Results demonstrate that the molecular connectivity model is an accurate predictive tool for the cuticle/water partition coefficients of a wide range of commercial chemicals and that it can be confidently used to assess their potential to penetrate and to accumulate in aboveground vegetation.