       Determination of Material Emission Signatures by PTR-MS and its Correlations with Acceptability Index Kwanghoon Han 1,* , Jensen Zhang 1 , P. Wargocki 2 , H. N. Knudsen 3 and Beverly Guo 1 1 Building Energy and Environmental Systems Laboratory (BEESL), Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY13244, USA 2 International Centre for Indoor Environment and Energy, Department of Mechanical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark 3 Danish Building Research Institute, Aalborg University, Hørsholm, Denmark * Corresponding email: kwhan@syr.edu SUMMARY The objectives of this study were to determine VOC emission signatures by PTR-MS, and to explore the correlations between PTR-MS measurements and acceptability index levels previously measured by human subjects. Emissions from nine materials, the same ones previously studied by DTU and SBi to investigate human exposure-response relationships in terms of acceptability index, were measured individually in a 50-L-small-scale chamber with similar area-specific airflow rates as in the test with human subjects. Chamber air was sampled by PTR-MS to determine emission signatures followed by sorbent tube sampling for identifying major VOCs emitted from each material and for comparing with PTR-MS emission signatures. The study focused on the analysis of the concentration level and composition of emitted VOCs causing acceptability differences among the tested materials. Results show high correlation between PTR-MS measurements and acceptability when the sum of individual VOC odor indices was used to represent the emission strength by PTR-MS. KEYWORDS Emission signature, PTR-MS, GC/MS, VOC odor, signal processing INTRODUCTION Proton transfer reaction mass spectrometry (PTR-MS) is relatively a new instrument that has attracted many engineers’ and scientists’ interests in the recent few years. Unlike Gas Chromatographic (GC) methods, PTR-MS allows numerous VOCs of interest to be monitored with a high sensitivity (detection limit: 10-100 pptv) and a rapid response time, usually less than 100 ms (Lindinger et al. 1998). Due to its ability for on-line monitoring, practical/handy identification and detection of VOCs, there have been many applications in atmospheric, food research, forensic investigation, environmental science and medical research (Lindinger et al. 1998). In this study, we explored the feasibility of using PTR-MS to determine the VOC emission signatures of building materials and furnishings, and to investigate the relationship between the emission signatures and the emission acceptability determined by human subjects. The results of this study will be useful for further development of methods for: 1) on-line material identification and detection, 2) VOC source detection under field conditions and 3) deeper understanding of VOC behaviors in a material and its impact on human sensory responses. MATERIALS and METHODS The same nine (9) building materials (Table 1) previously studied in the subjective sensory assessments by human subjects were tested for their VOC emission compositions and concentration levels by using PTR-MS and GC/MS to analyze air samples taken from the exhaust of an environmental chamber containing a test specimen. For each test, the material