Figure 1.

²J_HP coupling prevents direct measurement of glyphosate permeation of liposomes with standard ¹H-spectra. Glyphosate showed one singlet at 3.74 ppm and one doublet at 2.99 ppm in the ¹H NMR spectrum with solvent suppression (black line). Strong ²J_HP coupling led to formation of a doublet centered at 2.99 ppm. Upon Pr³⁺ addition to the liposome suspension, the spectrum changed (red line). The glyphosate peaks outside the liposomes were shifted downfield (doublet at 3.2 ppm and singlet at 3.79 ppm), and the peaks inside the liposomes broadened due to chemical exchange. As a consequence, the individual doublet peaks overlapped, almost coalescing into a singlet and rendering peak shape analysis impossible. Both spectra in this figure were collected at pH 7.5.