Trace level analysis of VOCs and semi-VOCs in aqueous solution using a direct insertion membrane probe and trap and release membrane introduction mass spectrometry

A new design for a trap and release membrane introduction mass spectrometry (T&R-MIMS) system using a removable direct insertion membrane probe (DIMP) for combined trace level analysis (low or sub ppb range) of volatile (VOC) and semi-volatile organic compounds (SVOCs) is reported. The system differs from the original T&R-MIMS system (M. Leth and F. R. Lauritsen, Rapid Commun. Mass Spectrom., 1995, 9, 591) as it uses a removable DIMP probe to place a capillary membrane loop inside the ion source block exactly between two parallel filaments. The more versatile DIMP-T&R-MIMS system can be operated, during the trapping step of T&R-MIMS analysis, in the standard MIMS mode for VOC detection; during the T&R-MIMS thermal desorption step needed for SVOC analysis, the system permits faster and more uniform heating of the membrane, thus SVOC sensitivity is improved and memory effects are minimized.