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Physical & Chemical properties

Water solubility

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Description of key information

The solubility of NBPT in water was determined to be 43.04 g/L. Results were based on the average of triplicate radioassays of three saturated solutions over a sixty-six hour incubation period at 25°C. 
The densities of the saturated NBPT solutions were approximately 1.04 g/mL, and the pH's of the solutions were approximately 7.26.

Key value for chemical safety assessment

Water solubility:
43.04 g/L
at the temperature of:
25 °C

Additional information

This study was designed to meet the requirements of the EPA Pesticide Assessment Guidelines Subdivision D, Physical and Chemical Properties, Series 63-8, Solubility, following the broader guidance proved in TSCA requirements specified in 40 CFR 796.1840. This study was also conducted in accordance with the study protocol and applicable PTRL West Standard Operating Procedures. The solubility of N-(n-butyl)phosphorothioic triamide (NBPT) in aqueous solution was examined. The purity of the test substance was confirmed to be ≥ 99% by reverse phase HPLC before experimental start. An isotopically diluted sample of solid 14C]-NBPT was prepared by thoroughly mixing methanol solutions of [14C]_NBPT and non-labeled NBPT followed by evaporation of the solvent. The specific activity of the isotopically diluted NBPT was determined by liquid scintillation counting. Triplicate Erlenmeyer flasks containing an excess of the isotopically diluted [14C]_NBPT in sterile deionized water were prepared, placed in an incubator in the dark and stirred slowly, at constant temperature (25 ± 1°C). Subsamples were removed from each flask at 0-time and following - 24, 29, 45 and 66 hours of agitation. The subsamples were filtered, and triplicate aliquots were taken for radioassay by liquid scintillation counting.The average solubility of NBPT in aqueous solution after 66 hours of agitation was determined to be 43.04 g/L. Following the incubation period the solutions were reexamined by HPLC, which demonstrated the stability of NBPT throughout the experiment. The mean density of an aqueous saturated NBPT solution after 66 hours of agitation was determined to be 1.036 g/mL by weighing aliquots (0.100 mL) of NBPT solution.