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Hydrolysis Test

This study was conducted as specified by US. EPA under TSCA Chemical Fate Testing Guidelines, listed at 40 CFR § 796.3500 to fulfill the data requirements for Hydrolysis as a Function of pH at 25°C.

The study examines the rate of hydrolysis of [14C]NBPT in sterile aqueous buffer at pH 3, 7 and 11. Solutions were maintained in the dark at 25°C. [14C]NBPT and its degradates were quantified by high-pressure liquid chromatography (HPLC) with cochromatography with NBPT analytical reference substance. HPLC assignments were confirmed by TLC co-chromatography of selected 14C-samples with NBPT analytical reference substance.

The degradates were separated and quantitated by HPLC analysis. The spectra indicate that Degradate 1 is N-(n-butyl)thiophosphoric diamide, formed by hydrolysis of NBPT at one of the amide substituents. The proton and 31P NMR spectra of Degradate 2 identify it as butylamine and these spectra indicate that this product is butylamine results from hydrolysis of NBPT and/or Degradate 1.

The estimated half-life at 25°C of the test material at pH 3, 7 and 11 was 58 minutes, 92 days and 16 days respectively.

Ready Biodegradability Test

The study was conducted according to the Environmental Protection Agency (EPA) Toxic Substance Control Act (TSCA) Part 796 - Chemical Fate Testing Guidelines Section 796.3260, Ready Biodegradability: Modified Sturm Test.

The test substance, N(n-butyl) phosphorothioic triamide (NBPT), was evaluated for biodegradability by exposing it to an activated sludge microbial inoculum in a mineral medium under aerobic conditions. The inoculum was activated sludge obtained from a wastewater treatment plant receiving predominantly domestic sewage.

The average percent theoretical CO2 produced by the test substance, N(n-butyl) phosphorothioic triamide (NBPT), was 9.51 ± 0.64 %ThC02 through day 28 of the study.

Therefore the test substance, N(n-butyl) phosphorothioic triamide (NBPT), can not be classified as readily biodegradable according to the criteria outlined in the TSCA Guideline.

Adsorption Coefficient

The adsorption coefficient (Koc)of the test material has been determined uuing an HPLC Screening method, Method 121 of the OECD Guidelines for Testing of Chemitals, 22 January 2001. The results are shown in the following table:

pH

Koc

Log10Koc

5.5

<17.8

<1.25

8.5

<17.8

<1.25

The adsorption coefficient (Koc) of the test material has been determined to be <17.8, log10 Koc <1.25.