As long as sample preparation and instrument measurement conditions are comparable for two samples, NMR spectroscopy is a highly reproducible method. The standard deviation of the chemical shifts derived from the HNMR spectra of two independently prepared samples of the sesquiterpenoid lactone, α-santonin, in CDCl3 can serve as an example: measured independently on two different instruments, the deviation was less than 5 ppb (0.005 ppm), equivalent to 2.5 Hz at 500 MHz, despite different sample concentrations (~50 mM in DMSO-d6 vs. 100 mM in CDCl3).