Kore Systems:
Custom PTR

PTR/Atmospheric Pressure Chemical Ionisation.

University of Nottingham, UK

This instrument has been designed for the University of Nottingham. In one mode it operates using chemical ionisation in a low pressure (~1mbar) drift tube, e.g. by using PTR (proton transfer reaction). The second mode employs APCI (atmospheric pressure chemical ionisation).


To switch between the two modes requires a mechanical swap of the “front end” source. The open architecture of the instrument allows this to be done easily. Each mode can be used to both create both positive and negative ion mass spectra.


A TOF-MS linked to a PTR system is highly attractive because it offers real-time, high time resolution, high sensitivity detection of all analyte species in parallel. In a quadrupole PTR-MS, as each new species (m/z) is added to the list of molecules to be monitored, less time can be spent monitoring the other species of interest, thus the sensitivity per molecule drops in proportion. Also, if 10 species are monitored for 100ms, then data for each individual species is only acquired every second, and thus time resolution suffers when multiple species are monitored.


These limitations do not apply to TOF-MS. All ions are detected; there is no concept of ‘having to choose which mass to monitor’.


The PTR front end is a Kore design, and comprises a hollow cathode glow discharge source (HCGD) on the right side, a source drift region (to allow other chemistries to be achieved), and a PTR drift section into which the analyte molecules are introduced for collision with the primary ion beam. Just visible in the photograph are the parallel drift electrodes.


Prof. Andy Taylor and Dr. Rob Linforth have pioneered the use of atmospheric pressure chemical ionisation methods for the detection of flavour molecules using conventional quadrupole mass spectrometers. They are now looking to extend the speed and sensitivity in their research by using TOF-MS, as well as extending their ionisation methods to include proton transfer reaction chemistry (PTR).


An intriguing aspect of their research methodology is to monitor the appearance of flavour molecules with elapsed time on the breath of a person who is sampling a food product. Naturally, the basic experiment is quite short, and as much data as possible needs to be gathered in that time. The parallel detection capabilities of TOF-MS are very attractive from this point of view. One of the aims of this instrument is to be able to acquire sufficient data in 0.1 seconds to allow investigation of concentration variations with this time resolution.


Kore Technology is a centre of excellence in time-of-flight mass spectrometer technology and has a very strong R&D capability in terms of its personnel, all of whom have been heavily involved in a variety of analytical instrumentation development programmes.


If you have any questions please feel free to contact us via our online form or telephone us for more information, we offer a wide range of products and services to suit your requirements.


If you wish to purchase our products, please contact Kore sales at sales@kore.co.uk, or call +44 (0)1353 653030.

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