Proton Transfer Reaction - Mass Spectrometry
What is PTR-MS?
PTR-MS (Proton Transfer Reaction – Mass Spectrometry) technology enables real-time measurement of volatile organic compounds (VOCs). Originally developed by scientists at the Institut für Ionenphysik at the University of Innsbruck, Austria this technology has been commercialized by IONICON Analytik.
PTR-MS allows the simultaneous real-time monitoring of volatile (organic) compounds (VOCs) like acetone, acetaldehyde, methanol, ethanol, benzene, toluene, xylene and many others present in ambient air. The IONICON PTR-MS instruments are known for their market-leading detection limits in the single-digit pptv-range and their real-time monitoring capabilities.
IONICON Analytik is continuously setting new benchmarks in online mass spectrometry and the only company to produce high quality PTR-MS instruments for scientists all over the world.
What are the advantages of PTR-MS?
Online quantification without calibration
PTR-MS provides absolute quantitative analysis in real-time. The generation of the precursor reagent ions and the chemical ionization of the VOCs are individually controlled and spatially separated processes. This leads to constant and well defined conditions in the drift tube (unlike IMS, APCI-MS and similar technologies) making the determination of absolute concentrations possible without the use of gas standards.
Market-leading low online detection limit
H3O+ ions do not react with any of the major components present in clean air due to their low proton affinity. Unlike other technologies (e.g. SIFT-MS) PTR-MS does not dilute low concentrated samples by a carrier gas and does not lose precursor ions on their way through a mass filter between the ion source and the drift tube. This makes PTR-MS very sensitive to trace gases in the sample air. Very high intensities of precursor ions and thus real single-digit pptv-range detection limits are the resulting benefits of our PTR-MS technology.
Soft and efficient chemical ionization
Proton transfer from H3O+is a soft ionization method, keeping fragmentation rates rather low as compared to e.g. electron impact ionization often used in GC-MS instruments, thus minimizing coincidences in the mass spectra and improving the identification capability.
Switchable reagent ions (SRI)
By using not only H3O+ but also NO+ and O2+ as reagent ions as an optional configuration of IONICON PTR-MS instruments, separation of isomeric compounds in real-time is now possible. Additionally, also substances that could not be ionized with H3O+ due to their low proton affinity are now detectable.
Note: Because of a highly sophisticated ion source design (hollow cathode discharge) we do not need a signal-diminishing mass filter to select these precursor ions, thus we can achieve outstanding sensitivity also for NO+ and O2+ ionization.
No sample preparation
A major advantage of PTR-MS is that the samples do not need to be prepared before the measurement (e.g. pre-concentration or chemical separation procedures), thus whole-air samples can be introduced directly into the drift tube allowing for dynamic headspace sampling or VOC flux measurements.
The real-time advantage
PTR-MS is an "online" mass spectrometric technology providing real-time data due to its very fast response time of less than 100ms. Averaging over minutes and long sampling intervals as in the case of less sensitive or "offline" technologies are not necessary with an IONICON PTR-MS.
The liberty to choose between quadrupole and time of flight MS
IONICON offers a broad range of different PTR-MS products and gives you the choice between different quadrupole mass filters or a time of flight analyzer (allowing to distinguish isobaric product ions) for maximum flexibility and adaptation to your needs.
Robust and easy to use
No gas supply is necessary to operate an IONICON PTR-MS (i.e. for H3O+ and NO+ reagent ions). Our instruments are light-weight (e.g. the portable Compact PTR-MS weights only 55 kg) and space-saving which clearly puts us ahead of competing technologies. IONICON PTR-MS systems are often used for field campaigns or variable location measurements and can be operated in nearly every environment. Only 15 minutes after pressing the power-button, the Compact PTR-MS is ready to measure. Little maintenance and small operating costs complete the whole package.
You're not yet convinced? Click here for some testimonials and references of our customers or test a PTR-MS free or charge!
Learn more about the IONICON PTR-MS technology here.
Related document:
PTR-MS technology overview folder (0.4 MB .pdf - 8 pages A4)
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