Abstract: OBJECTIVE: To find suitable concentration ranges for future urine metabolomics studies. METHODS: Morning urine samples from six volunteers were collected and mixed equally before samples were assigned to three groups. In control group,no preservative was used. In the sodium azide (NaN₃) group,NaN₃ was added to the urine at final concentrations of 0.1,1 and 10 mmol/L. In the boric acid group,boric acid was added with final concentration of 2,20 and 200 mmol/L. All samples were detected using the ultra-performance liquid chromatography tandem quadrupole time of flight mass spectrometry (UPLC/Q-TOF MS/MS) technique and data were analyzed by chemometrics method such as principal component analysis (PCA),partial least-squares discriminant analysis (PLS-DA) and orthogonal projection to latent structures discriminant analysis (OPLS-DA) to compare with metabolic profiles in different treatments. RESULTS: The PLS-DA scores plot show that there was no obvious separate trend between the control group and the three NaN₃ groups. The same observed between the control group and the 2 mmol/L boric acid treatment group. However,significant differences in urine metabolites were observed between the 200 mmol/L boric acid and the control groups. CONCLUSION: NaN₃ at a concentration of 0.1-10 mmol/L and boric acid at a concentration of 2 mmol/L were found to be suitable for future urine metabolomics research based on the UPLC/Q-TOF MS/MS technology.

Key words: urine, preservative, UPLC/Q-TOF MS/MS, metabolomics