Prediction of the environmental distribution of alkyl dinitrates -: Chromatographic determination of vapor pressure p0, water solubility SH2O, gas-water partition coefficient KGW (Henry's law constant) and octanol-water partition coefficient KOW

Alkyl nitrates are complex mixtures of homologues and isomers and are part of the large NOy pool of important atmospheric trace compounds. The knowledge of their physico-chemical parameters allows to forecast their partitioning into the environment. Water solubility, octanol-water partition coefficient, vapor pressure, and gas-water partition coefficient have been determined for 26 alkyl dinitrates by RP-HPLC and HRGC, respectively. Octanol-water partition coefficient (K-OW) and water solubility (S-H2O) were determined by C18 reversed-phase liquid chromatography using phenylalkanes as reference standards. Retention data obtained with methanol-water mixtures as eluents were extrapolated to 100% water. The vapor pressures were determined by capillary gas chromatography on a non polar stationary phase (CP-Sil 2, Chrompack). The octanol-water partition coefficients ranges from log K-OW = 1.4 for 1,2-ethyl dinitrate up to log K-OW = 5.9 for 1,2-decyl dinitrate, respectively. The experimental results are within +/- 0.15 log units in agreement with calculations of log K-OW by the increment method according to Hansch and Lee. Water solubilities are in the range of 154 mol/m(3) (23.1 g/L) for I,2-ethyl dinitrate and 0.002 mol/m(3) (0.5 mg/L) for 1,2-decyl dinitrate, respectively. The vapor pressures p(L)(0) ranges from 196 Pa for 1,2-ethyl dinitrate to 0.01 Pa for 1,10-decyl dinitrate (subcooled liquid value). The gas-water partition constants (dimensionless) or Henry's law constants ranges from K-GW = 0.0005 (H = 1.28 Pa m(3)/mol) for 1,2-ethyl dinitrate to K-GW = 0.020 (H = 51.1 Pa m(3)/mol) for 1,2-decyl dinitrate.