SOGGY: Solvent-optimized double gradient spectroscopy for water suppression. A comparison with some existing techniques

Abstract

Excitation sculpting, a general method to suppress unwanted magnetization while controlling the phase of the retained signal [T.L. Hwang, A.J. Shaka, Water suppression that works. Excitation sculpting using arbitrary waveforms and pulsed field gradients, J. Magn. Reson. Ser. A 112 (1995) 275–279] is a highly effective method of water suppression for both biological and small molecule NMR spectroscopy. In excitation sculpting, a double pulsed field gradient spin echo forms the core of the sequence and pairing a low-power soft 180°(− x) pulse with a high-power 180°( x) all resonances except the water are flipped and retained, while the water peak is attenuated. By replacing the hard 180° pulse in the double echo with a new phase-alternating composite pulse, broadband and adjustable excitation of large bandwidths with simultaneous high water suppression is obtained. This “Solvent-Optimized Gradient–Gradient Spectroscopy” (SOGGY) sequence is a reliable workhorse method for a wide range of practical situations in NMR spectroscopy, optimizing both solute sensitivity and water suppression.