A New PTR-MS Reaction Cell Combining Linear and Oscillating Fields (EMSC 2018)

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New PTR-MS Reaction Cell – Vocus

This EMSC 2018 poster introduces the Vocus PTR-MS reaction cell and presents data demonstrating PTR-MS sensitivity gains and LOD improvements when coupled to a time-of-flight mass analyzer (PTR-TOF).

Traditional PTR-MS reaction cell designs use a stack of metal lenses connected by a series of resistors to produce a linear drift field. The stable, tuneable drift field (E) enables precise control over the distribution of water clusters and the electrostatic reaction time. But, because of scattering and diffusion within the drift tube, many analyte ions are not transmitted out of the drift tube toward the mass analyzer – thereby limiting the achieved sensitivity.

The Vocus PTR-MS reaction cell maintains the operation parameters required for fast, quantitative PTR-MS analysis, with two unique design features that significantly increase sensitivity. By superimposing an oscillating RF field on top of a DC field, analyte ions are focused toward the center axis of the reaction cell and are efficiently transmitted into the mass analyzer. The reaction cell is built using a resistive glass tube, rather than the traditional lens stack. This allows the application of the RF focusing field, while producing a more uniform DC field than the traditional lens stack.

The Vocus PTR-TOF is a proton transfer reaction mass spectrometer (PTR-MS) that is used for sensitive, real-time detection of volatile organic compounds (VOCs) in industrial, laboratory, and field applications. The instrument combines TOFWERK’s novel Vocus proton transfer reaction cell with our high performance time-of-flight technology to offer you market leading sensitivity and mass resolving power.