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The adsorption/desorption of IOA was assessed through the estimation of the adsorption coefficient (Koc). Using an HPLC estimation method, the log Koc was determined to be 3.18. Based on the adsorption coefficient of IOA, it is expected to have low to slight mobility in soil.

 Henry’s Law constant is used to describe the escaping tendency for a substance that is dissolved in water. For IOA, Henry’s Law constant was not experimentally measured, nor was it estimated using QSARs. It was derived using a widely accepted expression for determining Henry’s Law constant from experimentally determined vapor pressure and water solubility values. Henry’s Law is given by: 

               Hc= PA/[A]water

where PA is the partial pressure of the substance A, and [A]water is the concentration of the substance in water. IOA has a calculated Henry’s Law constant of 1780 Pa*m3/mol (0.018 atm*m3/mol) at 23.1 °C. The vapor pressure used to calculate Henry’s Law constant is the mean of the vapor pressure regressions extrapolated to 23.1 °C:

logP (Pa) = -2.64 + 0.0162*T(K)

logP (Pa) = -3.29 + 0.0178*T(K)

Based on this value, IOA is likely to volatilize from the aquatic compartment into the atmosphere.

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