Development of a Sensitive High-Resolution Mass Spectrometry Approach for Urea Nitrogen Quantitation in Small Volumes of Bronchoalveolar Lavage Fluid (BALF). - Ulmer CZ; Smith B; Thonkulpitak J; Hardin J; Danilenko U; Frame T; Cheng PY; Vesper HW (Journal of the American Society for Mass Spectrometry, 2020)