Measurement of octanol-air partition coefficients using solid-phase microextraction (SPME) - application to hydroxy alkyl nitrates

Multifunctional organic compounds are thought to constitute a major compone nt of the organic matter found in atmospheric particles. Their partitioning into the organic matter depends on their structure, their chemical propert ies and the properties of the absorbing matrix. It was recently shown that octanol is a suitable surrogate for organic particles and the octanol-air p artition coefficient (K-OA) was suggested as a useful tool for estimating t he partitioning of organic compounds into atmospheric particles that contai n high organic mass fractions. In this paper, we present a new and simple t echnique for the determination of KOA using solid phase microextraction (SP ME) relative to a known Henry's law constant. We apply the technique for th e determination of K-OA of beta-, gamma- and delta -C-3-C-5 hydroxy alkyl n itrates. The temperature dependence of K-OA for some of the compounds is al so measured. It is shown that the solubility constants of these compounds a re higher in octanol than in water and that the solubility in octanol incre ases with the length of the hydrophobic chain and with increasing distance between the hydroxy and the nitrooxy groups. Partition coefficients between the gas and particulate phase (K-p) are calculated using the determined K- OA values and their atmospheric implications are discussed. (C) 2001 Elsevi er Science Ltd, All rights reserved.