Fig. 2.

Z spectra of 200 mM glycogen in PBS buffer at 37°C (pH 7.4) acquired at 9.4 T (5-mm NMR tube) and 4.7 T (spherical bulb) by using a 10-s presaturation pulse and with a B₁ of 1.9 μT and repetition time of 28 s. Notice the better definition of the CEST effect at a higher field due to the increased chemical shift difference in hertz.