Relaxometric Magnetic Resonance Imaging (MRI) was used to extract the relaxation time T 1 from bulk salt solutions. NaCl and Na 2 SO 4 solutions were prepared at the concentrations of 1, 2, and 4 mol/kg and 0.2, 0.5, and 1 mol/kg, respectively (Supplemental Material, Table ) and filled in 10 mm diameter NMR glass tubes. All measurements were done at room temperature (20 • C). Dissolved oxygen was removed by stripping the samples with a helium gas stream for 5 minutes, and tubes were immediately closed to prevent re-diffusion of air. The glass tubes were arranged in a bundle so that T 1 could be determined simultaneously for all different concentrations using an imaging pulse sequence. MRI images of the salt solutions were recorded using a Bruker Ultra-Shield super-wide bore magnet, with a magnetic field B 0 = 4.7 T (200 MHz) equipped with a wide-bore gradient system and a GREAT60 gradient amplifier, operated by a Bruker Avance III console. A multi-slice multi-echo (MSME) pulse sequence with inversion recovery (IR) preparation at intervals t inv = 0.2 to 8 s (logarithmically sampled) was used. A reference scan without IR preparation was performed at the end of the image series. Other pulse sequence parameter settings: the slice thickness was equal to 3 mm, the field of view was 30 mm × 30 mm, the matrix size was 128 × 128 points, the echo time t E was 5 ms and the recycle delay time t R was set to 10 s. The first step of the evaluation was performed by complex division of the images with IR preparation by the reference image to eliminate the dependence of the signal intensity on the transverse relaxation time. A value of T 1 was obtained for each voxel by fitting a single exponential function to the data. Finally, a single value of T 1 was obtained for each sample by averaging the values over a region of interest defined by the entire cross section of the tubes (Supplemental Material, Table ).