Sample preparation method to minimize chemical shift variability for NMR-based urinary metabonomics of genetically hypertensive rats.

Urinary metabonomics based on proton nuclear magnetic resonance ((1)H NMR) has been widely employed to study metabolic differences associated with gene function and pathophysiological and toxicological stimuli. However, the chemical shift variability of (1)H NMR signals, which is due to differences in pH and ionic strength among urine samples, remains an outstanding problem for efficient data mining. Thus, we have proposed an improved sample preparation method where urine samples are lyophilized and reconstituted in a buffer solution (pH 7.