Pseudoephedrine

CAS RN: 90-82-4

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 73(SRC), determined from a log Kow of 0.89(2) and a regression-derived equation(3), indicates that pseudoephedrine is expected to have high mobility in soil(SRC). However, the pKa of pseudoephedrine is 10.25(4), indicating that this compound will primarily exist in the cation form in the environment and cations generally adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(4). Pseudoephedrine is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 8.3X10-4 mm Hg(SRC), determined from a fragment constant method(5). Biodegradation data were not available(SRC, 2007).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 73(SRC), determined from a log Kow of 0.89(2) and a regression-derived equation(3), indicates that pseudoephedrine is not expected to adsorb to suspended solids and sediment(SRC). A pKa of 10.25(4) indicates pseudoephedrine will exist almost entirely in the cation form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process(5). According to a classification scheme(6), an estimated BCF of 3(SRC), from its log Kow(2) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data were not available(SRC, 2007).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), pseudoephedrine, which has an estimated vapor pressure of 8.3X10-4 mm Hg at 25 deg C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase pseudoephedrine is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 4 hours(SRC), calculated from its rate constant of 9.9X10-11 cu cm/molecule-sec at 25 deg C(SRC) that was derived using a structure estimation method(3). Pseudoephedrine does not contains chromophores that absorb at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight(4).
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