biostudies-literatureUnknown61(2)Jordan JProton-transfer-reaction-mass spectrometry (PTR-MS) provides real-time analysis of volatile organic compounds (VOCs) relevant to atmospheric research, food and flavor characterization, industrial process control, and medical applications. However, PTR-MS is inherently limited in its ability to resolve isomers of molecules with the same mass-to-charge ratio (m/z). To address this selectivity constraint, we coupled a time-of-flight (TOF) based PTR-MS setup with a "Structures for Lossless Ion Manipulations Ion Mobility Spectrometry" (SLIM IMS) module. The integration of SLIM IMS introduces an additional separation dimension without compromising the real-time capability of PTR-MS. A custom designed SLIM device enabled efficient confinement and transmission of low mass ions (m/z < 300), which aJournal of mass spectrometry : JMSe70031https://www.ebi.ac.uk/biostudies/studies/S-EPMC12853077biostudies-literatureSelectivity Beyond Mass: Real-Time Isomer Separation Using SLIM IMS Coupled to PTR-MS.PMC12853077Sulzer PJordan AHanel GBeyer MKJordan JFugenschuh TLindinger CfalseSelectivity Beyond Mass: Real-Time Isomer Separation Using SLIM IMS Coupled to PTR-MS.Proton-transfer-reaction-mass spectrometry (PTR-MS) provides real-time analysis of volatile organic compounds (VOCs) relevant to atmospheric research, food and flavor characterization, industrial process control, and medical applications. However, PTR-MS is inherently limited in its ability to resolve isomers of molecules with the same mass-to-charge ratio (m/z). To address this selectivity constraint, we coupled a time-of-flight (TOF) based PTR-MS setup with a "Structures for Lossless Ion Manipulations Ion Mobility Spectrometry" (SLIM IMS) module. The integration of SLIM IMS introduces an additional separation dimension without compromising the real-time capability of PTR-MS. A custom designed SLIM device enabled efficient confinement and transmission of low mass ions (m/z < 300), which a2026-01-01T00:00:00Z2026 Feb2026-06-16T07:12:30.121Z2026-06-16T03:09:55.453ZS-EPMC128530774160720110.1002/jms.70031