Entech Instruments Inc. 1 article published in JoVE Biochemistry Capturing Actively Produced Microbial Volatile Organic Compounds from Human-Associated Samples with Vacuum-Assisted Sorbent Extraction Joann Phan1, Joseph Kapcia III1, Cynthia I. Rodriguez2, Victoria L. Vogel3, Daniel B Cardin3, Sage J. B. Dunham3, Katrine Whiteson1 1Department of Molecular Biology and Biochemistry, University of California Irvine, 2Department of Ecology and Evolutionary Biology, University of California Irvine, 3Entech Instruments Inc. This protocol describes the extraction of volatile organic compounds from a biological sample with the vacuum-assisted sorbent extraction method, gas chromatography coupled with mass spectrometry using the Entech Sample Preparation Rail, and data analysis. It also describes culture of biological samples and stable isotope probing.