Pharmasan Labs, Inc. 1 article published in JoVE Chemistry Integration of Miniaturized Solid Phase Extraction and LC-MS/MS Detection of 3-Nitrotyrosine in Human Urine for Clinical Applications Xiaoguang Sunny Li1, Shu Li1, Melissa Ahrens2, Gottfried Kellermann1,2 1Pharmasan Labs, Inc., 2NeuroScience, Inc. A selective and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method coupled with an efficient solid phase extraction on a mixed-mode cation-exchange (MCX) 96-well microplate was developed for the measurement of free 3-nitrotyrosine (3-NT) in human urine with high throughput, which is suitable for clinical applications.