Recovery characteristics of different tube materials in relation to combustion products
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ORIGINAL RESEARCH
Recovery characteristics of different tube materials in relation to combustion products M. Karjalainen 1
&
A. Kontunen 1 & M. Mäkelä 1 & O. Anttalainen 2 & A. Vehkaoja 1 & N. Oksala 1,3 & A. Roine 1
Received: 29 May 2020 / Revised: 1 July 2020 / Accepted: 2 July 2020 # The Author(s) 2020
Abstract Common challenge in gas analyzers such as Ion Mobility Spectrometers (IMS) integrated into a measurement system is the reduced analysis speed that is partially limited by the temporal carry-over of sample molecules. It is caused by adsorption and absorption of the molecules into the gas tubes of the analyzer. We studied the recovery times of common tube materials: polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), polyethylene (PE), steel 316 L, parylene C coated steel and Silconert® coated steel from organic combustion products. The tests were performed in two temperatures, at 25 °C and at 70 °C. In addition, detailed analysis was performed for PTFE tube material at 33, 50, 70 and 100 °C to observe the temperature relation of desorption. Uncoated steel was found to have the best performance in increased temperature applications due lack of absorption. Major advantages from coatings compared to plane steel were not found. Plastics were found suitable materials in lower temperatures where adsorption exceeds absorption. Keywords Carry over . Instrumenting . Recovery . Tubing . Sorption
Introduction Gas analyzers based on ion mobility spectrometry (IMS) are used in various application areas such as medicine, process industry, security and research ([1, 2]. Due to its relative simplicity and ability to function at atmospheric pressure, IMS technology enables low-maintenance gas analysis even outside laboratory conditions. However, residual signal produced by the previously sampled gas results in so called carry-over effect that should be addressed in all applications. Recovery time, i.e. the time required for the system to clear out the carryover is dependent on analyzer materials, temperature, volume and control of the contaminating molecules. Recovery time can be improved by increasing the temperature, reducing surface area, and by optimizing material selection and filtration
* M. Karjalainen [email protected] 1
Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
2
Olfactomics Oy, Tampere, Finland
3
Centre for Vascular Surgery and Interventional Radiology, Tampere University Hospital, Tampere, Finland
methods utilized in the system ([3, 4]. These methods also have their downsides. Heating inherently increases the complexity and energy consumption of the system, reduces the number of applicable materials, and in some cases may also affect to the analyte composition by promoting chemical reactions. Minimizing the surface area by reducing of physical dimensions beyond a certain point further complicates the manufacturing of the system, and filtering potentially limits the range of detection. With correct materia
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