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Parathion Hydrolysis Revisited: In Situ Aqueous Kinetics by 1 H NMR
Environmental Science and Technology
  • Emma C. Wanamaker, Boise State University
  • G. C. Chingas, Boise State University
  • Owen M. McDougal, Boise State University
Document Type
Article
Publication Date
8-20-2013
DOI
http://dx.doi.org/10.1021/es402526n
Disciplines
Abstract

The kinetics of parathion (PTH) decomposition into para-nitrophenolate (pNP) and O,O-diethylthiophosphate (DETP) were measured in high-pH aqueous solutions at 20 °C by proton nuclear magnetic resonance spectroscopy (1H NMR). Reaction rates were determined over a 16 h observation time, in solutions with NaOD concentrations of 5.33 mM, 33.33 mM, and 100 mM, with NaCl added to fix ionicity. The pseudo-first-order rate constants for these systems were determined to be 1.9 × 10–4 min–1, 1.4 × 10–3 min–1, and 3.8 × 10–3 min–1 respectively. The slope of the linear plot of these rates against OD– concentration yielded the second-order hydrolysis rate constant 3.90 × 10–5 mM–1 min–1, valid over this pH range from 10.5 to 13. The data agree with some, and contradict other, earlier work. Our fitting procedure included background levels and allowed us to not only obtain reliable kinetic results but also to measure residual pNP and DETP impurity levels.

Citation Information
Emma C. Wanamaker, G. C. Chingas and Owen M. McDougal. "Parathion Hydrolysis Revisited: In Situ Aqueous Kinetics by 1 H NMR" Environmental Science and Technology (2013)
Available at: http://works.bepress.com/owen_mcdougal/44/