Application of the WATR technique for water suppression in 1H NMR spectroscopy in determination of the kinetics of hydrolysis of neostigmine bromide in aqueous solution

Article abstract of DOI:10.1111/j.2042-7158.1993.tb05598.x

Both ammonium chloride and guanidinium chloride were used to secure water suppression in ¹H NMR spectra using the 'Water Attenuation by T₂ Relaxation' (WATR) technique. The effect of phosphate buffer in the suppression was investigated over a range of pH values at 80 MHz. The spin-spin relaxation time of water protons at 80 MHz was found to reach a minimum at pH 7.3 in the presence of 0.1 M phosphate buffer and 1 M guanidinium chloride; these conditions were therefore chosen for subsequent use of the WATR technique in a study of the kinetics of hydrolysis of neostigmine bromide. The method was found to be very convenient for studies of the hydrolysis of this representative amide.