Tracking a Herbicide with High-Resolution NMR (IMAGE)
Caption
Washington University in St. Louis scientists Ge and d'Avignon with a horseweed plant in front of the high-resolution NMR machine they used to discover why the plant is resistant to the herbicide glyphosate. They were able to pick up a tiny frequency shift in the resonant frequency of the herbicide that signaled it had been moved into the plant vacuole, which can serve as a garbage disposal. The high-resolution NMRs in the Washington University facility can pick up changes of one part per million or one part per billion in resonant frequencies. To detect such small frequency changes the magnetic field used during experiments must be extremely homogeneous and stable. The High-resolution NMR spectrometers use "shims" (actually electrical-current shims whose function is analogous to that of mechanical shims) to achieve the necessary uniformity.
Credit
David Kilper/WUSTL
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