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Updated: May 9, 2026
Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
Published on: February 23, 2016
Parathion hydrolysis revisited: in situ aqueous kinetics by (1)h NMR
Emma C Wanamaker1, G C Chingas, Owen M McDougal
1Department of Chemistry and Biochemistry, Boise State University , 1910 University Drive, Boise, Idaho 83725-1520, USA.
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 ((1)H 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.
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