Urinary metabolomic methods
Hydrophilic interaction LC-based analysis of urine samples was conducted on a subset of 40 participants using ultrahigh resolution LC and MS (The LC profile was as follows: T: 0 min 90% (B), T: 2 min 60% (B), T: 5 min 40% (B), T: 7.5 min 40% (B), T: 7.6 min 90% (B), T: 10 min 90% (B). A 3 ¼L injection was applied. The heated spray ionization source (HESI) was set to the following parameters: Sheath gas flow rate of 50, the aux gas flow rate was set to 13, and the sweep gas flow rate was 3. The spray voltage was set to 3.5 akV with a capillary temperature of 275°C. The Aux gas heater temperature was adjusted to 425°C. The mass (MS1) acquisition range was as follows: 75–1000 m/z units at a mass resolution of 35,000 at ∼7.6 scans per second, microscan: 1, lock mass: off. The automatic gain control (AGC) was set to 1e6 and the ion injection time was 100 mS