d-methamphetamine

CAS RN: 537-46-2

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 900(SRC), determined from a structure estimation method(2), indicates that d-methamphetamine is expected to have low mobility in soil(SRC). The pKa of d-methamphetamine is 9.87(3), indicating that this compound will exist almost entirely 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). Volatilization from moist soil is not expected because the compound exists as a cation and cations do not volatilize. d-Methamphetamine is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 5.4X10-3 mm Hg at 25 deg C(SRC), determined from a fragment constant method(2). Biodegradation half-lives of 131 days in sandy loam and 502 days in loam(5) suggest that biodegradation in soil is dependent upon soil conditions(SRC).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 900(SRC), determined from a structure estimation method(2), indicates that d-methamphetamine is expected to adsorb to suspended solids and sediment(SRC). A pKa of 9.87(3) indicates d-methamphetamine 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(SRC). According to a classification scheme(4), an estimated BCF of 11(SRC), from its log Kow of 2.07(5) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is low(SRC). d-Methamphetamine present at 1090 ng/L, decreased in concentration to 675 and 529 ng/L in duplicate test runs over 15 days using river microcosm bioreactors(6), suggesting that biodegradation may be an important environmental fate process in water(SRC). However d-methamphetamine is expected to undergo hydrolysis in the environment due to the presence of functional groups that hydrolyze under environmental conditions(7).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), d-methamphetamine, which has an estimated vapor pressure of 5.41X10-3 mm Hg at 25 deg C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase d-methamphetamine 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 1 hour(SRC), calculated from its rate constant of 9.3X10-11 cu cm/molecule-sec at 25 deg C(SRC) that was derived using a structure estimation method(3). d-Methamphetamine does not contain chromophores that absorb at wavelengths >290 nm(4) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).
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