Fundamentals, Development and Applications of Ion Mobility Spectrometry (IMS) for Enhanced Trace Detection of Threat Agents
Lead Research Organisation:
University of Birmingham
Department Name: School of Physics and Astronomy
Abstract
The globalisation of our society means that there is an ever-increasing need, within homeland security, for reliable, real-time and sensitive detection of a wide range of substances that are a threat to our society. The chemicals to be detected range from explosives, through to illicit narcotics and chemical and biological agents. The ability to quickly and accurately measure these hazardous compounds, and distinguish them from a complex chemical environment, is vital to our nation's needs for its fight against crime and terrorism.Commonly used equipments for this type of security are often based on Ion Mobility Spectrometry (IMS), and which are often employed to screen people or objects. You may have experienced its application at airports if you had your laptop checked for traces of explosives, or if you walked through a Sentinel , used to screen people for trace amounts of explosives or narcotics. IMS is however, not only employed in transportation security, but also in military and civilian facilities.IMS operates by creating charged molecules (ions), which can either be positively or negatively charged. These ions migrate under the influence of an electric field with a mean constant velocity and collide with neutral molecules. Collisions and reactions (ion-molecule reactions) lead to the formation of other ionic species which may react with a trace gas. Changes in the resultant mobility of ions as they progress along an electric field are monitored and processed to try to identify any threat materials present.The IMS systems currently deployed have a number of limitations, including sensitivity and selectivity, which result in the technology not being fully exploited. The major limitation is low chemical specificity, restricting the type of compounds which can be readily detected. Many explosives and chemical threats just can not be detected. To overcome this requires a novel scientific approach, employing a detailed fundamental and phased research programme to understand the key chemical processes employed in IMS, and in particular to those occuring in the latest generation of drift tube systems being developed by Smiths Detection Ltd, Watford, UK. A systematic study is required which will investigate the ionization chemistry, the use of chemical dopants (to change the chemistry), and mode of operation (negative or positive ion mode, high or low electric field). An Ion Trap Mass Spectrometer (ITMS), coupled to novel IMS systems, will be the main device employed to study the complex ion chemistry. One of the advantages of the ITMS is that structural information on the ions can be obtained. By utilizing and tailoring the ion chemistry it will be possible to refine, extend, and enhance the operation of IMS. Together with lead scientists and engineers working in the world's largest company which manufactures, develops and markets IMS systems, the UK based company Smiths Detection Ltd (website address: www.smithsdetection.com and http://trace.smithsdetection.com/), we will pursue a four year programme of research to achieve the above objectives. Through Smiths Detection Ltd, this should lead to the development of a unique instrument, increasing the dimensionality of current IMS systems, ultimately leading to a new generation of chemical detectors to be deployed to fight crime and terrorism and increase security within the UK.
People |
ORCID iD |
| Chris Mayhew (Principal Investigator) | |
| Peter Watts (Co-Investigator) |
Publications
Agarwal B
(2011)
Use of proton transfer reaction time-of-flight mass spectrometry for the analytical detection of illicit and controlled prescription drugs at room temperature via direct headspace sampling.
in Analytical and bioanalytical chemistry
Bell A
(2008)
Fragmentations and reactions of protonated O,O-dimethyl ethylphosphonate and some isotopomers produced by electrospray ionisation in an ion trap mass spectrometer
in International Journal of Mass Spectrometry
Brown P
(2010)
Proton transfer reaction mass spectrometry investigations on the effects of reduced electric field and reagent ion internal energy on product ion branching ratios for a series of saturated alcohols
in International Journal of Mass Spectrometry
Feil S
(2008)
Investigations of electron attachment to the perfluorocarbon molecules c-C4F8, 2-C4F8, 1,3 C4F6, and c-C5F8
in International Journal of Mass Spectrometry
Jürschik S
(2010)
Proton transfer reaction mass spectrometry for the sensitive and rapid real-time detection of solid high explosives in air and water.
in Analytical and bioanalytical chemistry
Mayhew C
(2010)
Applications of proton transfer reaction time-of-flight mass spectrometry for the sensitive and rapid real-time detection of solid high explosives
in International Journal of Mass Spectrometry
Mayhew CA
(2009)
Selected ion flow tube studies to investigate the formation of acrylic and propionic acid protonated clusters in low power, low pressure RF plasmas.
in Chemical communications (Cambridge, England)
Parkes MA
(2014)
The kinetics and product state distributions from gas-phase reactions of small atomic and molecular cations with C2H4, C2H3F, 1,1-C2H2F2, C2HF3 and C2F4.
in Physical chemistry chemical physics : PCCP
Petersson F
(2009)
Real-time trace detection and identification of chemical warfare agent simulants using recent advances in proton transfer reaction time-of-flight mass spectrometry.
in Rapid communications in mass spectrometry : RCM
Philipp Sulzer (Author)
(2011)
Technical Advances in Proton Transfer Reaction-Mass Spectrometry and New Fields of Application
in American Laboratory
| Description | Fears of terrorism and the requirement to detect dangerous chemicals in low concentrations are leading to an ever-increasing need, within homeland security, for reliable, real-time and sensitive detection of a wide range of substances that are a threat to the safety of our society. The chemicals that need to be detected within a given environment (e.g. public places, airports, and battle sites) range from explosives through to narcotics and chemical and biological agents. The ability to quickly and accurately identify these hazardous compounds, and particularly within a complex chemical environment, is vital to any nation's needs for the fight against crime and terrorism. To achieve these objectives our research work is based on instruments that use ions as sensitive probes to the environment. Commonly used trace gas detection systems for this type of security are often based on Ion Mobility Spectrometry (IMS). IMS is the base technology in a wide range of Chemical Warfare Agent (CWA), drug and explosive detectors, and environmental monitors. We have constructed two instruments; both based on ion-mobility spectrometry, in collaboration with Smiths Detection Ltd, and in particular we have successfully interfaced an IMS to an ion trap mass spectrometer (ITMS). The ITMS adds an additional dimension over that of the usual IMS-quadrupole system in that it provides the potential for MSn studies to be performed thereby allowing information to be obtained about the structure of the product ions. The measurements taken with the IMS-ITMS have so far concentrated on organophosphates and organophosphates, and we have successfully demonstrated the versatility and powerful analytical features of the ITMS for interpreting ion mobility spectra. Our work has demonstrated the importance of understanding the nature and behaviour of ions within the ITMS that are relevant to the chemical reactions occurring in the IMS. The ITMS may not detect all the cluster ions formed in the IMS. However, detection, isolation and performing MS/MS on the core ions are sufficient for their further analysis. In addition to IMS we have also used Proton Transfer Reaction Mass Spectrometry (PTR-MS) in collaboration with Smiths Detection Ltd and Ionicon Analytik GmbH for threat agent detection. PTR-MS is essentially a low pressure IMS system without an electron gate. A major outcome from our investigations of proton transfer reactions is that we have observed an unusual bias sensitivity dependence for TNT detection on reduced electric field, which we relate to unexpected ion-molecule chemistry based upon comparisons of measurements taken with related nitroaromatic compounds and electronic structure calculations. This dependence provides an easily measurable signature that we propose can be used to provide a rapid highly selective analytical procedure to minimise false positives for the detection of TNT. This has the potential of making instrumentation cost effective for use in security areas. Our studies have shown that an understanding of fundamental ion-molecule chemistry occurring in drift tube environments is essential if selectivity and sensitivity are to be improved. This opens up new areas of research for a broad range of applications from health sciences through to atmospheric chemistry. |
| Exploitation Route | Our scientific underpinning research programmes aids in improving the sensitivity and selectivity of analytical instruments based on soft chemical ionisation processes occurring within a drift tube environment. In particular we have demonstrated that key operational parameters can be changed to provide high selectivity. An important discovery was the observation of an unusual bias sensitivity dependence for TNT detection. This dependence provides an easily measurable signature that can be used to provide a rapid highly selective analytical procedure to minimise false positives for the detection of TNT, and has the potential of making instrumentation cost effective for use in security areas. Although for sometime the observations could not be explained, we have, through extensive DFT calculations and further experiments using a PTR-ToF-MS provided by Smiths Detection Ltd during the time period of this project, proposed a previously unobserved ion-molecule reaction process to explain the anomalous dependence in the detection sensitivity for TNT. This study with TNT has wider implications beyond that of Homeland Security. The observation that drift-tube ion-molecule chemistry can be discriminated by switching bias fields and reagent ions opens a new dimension for chemical ionisation techniques and drift tube technology. The two-dimensional parameter space offers the potential for unprecedented easy detection capabilities for specific marker molecules in areas such as food security, breath analysis, atmospheric chemistry, etc. Of course the drift tube reaction pathways have to be understood and suitable markers identified. Potential development of analytical instrumentation with companies such as Smiths Detection Ltd (IMS and PTR-MS), KORE Technology Ltd (PTR-MS) and Ionicon Analytik GmbH (PTR-MS). |
| Sectors | Chemicals,Environment,Healthcare |
| Description | Of the research outcomes for enhanced trace detection of threat agents using ion mobility devices, I believe the most significant is teh unusual behaviour observed for the explosives TNT and TNB. That sensitivity initially increased with increasing reduced electric field was a complete mystery. Despite presentations at various international conferences, no one could explain the results. However, by use of Gaussian 09, DFT calculations gave us an indication of what is happening, and experiments confirmed the proposed reaction process, which had hitherto not been observed before and therefore advanced our understanding of potentially important ion-molecule reactions occuring in drift tube environments. Although acaedmically interesting, Importantly this dependence provides an easily measurable signature that can be used to provide a simple, rapid and highly selective analytical procedure for the detection of TNT. This has major implications for Homeland Security, where a high accuracy in the identification of TNT is required to minimise false positives. An important consequence of this discovery is that low resolution and hence cheap mass spectrometers in combination with low pressure drift tubes and soft chemical ionisation can be used to detect TNT, thereby making instrumentation cost effective for use in security areas such as airports and public buildings. This study also opens up new areas of research whereby an understanding of fundamental ion-molecule chemistry occurring in low-pressure drift tubes could be used to exploit selectivity and sensitivity for a broad range of applications from health sciences through to atmospheric chemistry. The discovery with TNT has wider implications beyond that of Homeland Security. The observation that drift-tube ion-molecule chemistry can be discriminated by switching bias fields opens a new dimension for proton transfer reaction mass spectrometric techniques. The two-dimensional parameter space offers the potential for unprecedented easy detection capabilities for specific marker molecules in areas such as food security, breath analysis, atmospheric chemistry, etc. Beneficiaries: Manufacturers of analytical devices based on drift tube technology, e.g. Smiths Detection Ltd, KORE Technology Ltd, and Ionicon Analytik GmbH Contribution Method: We have discovered and explained through detailed and thorough experimental measurements and theoretical calculations the chemical pathwyas that lead to an unusual behaviour in the detection of TNT using proton transfer reaction processes. |
| First Year Of Impact | 2008 |
| Sector | Aerospace, Defence and Marine,Security and Diplomacy |
| Impact Types | Cultural,Economic |
| Description | Applications of proton transfer reaction chemistry for the detection of solid and liquid explosives |
| Amount | £96,168 (GBP) |
| Funding ID | IRC2010/ITT122 |
| Organisation | Home Office |
| Sector | Public |
| Country | United Kingdom |
| Start | 01/2011 |
| End | 06/2014 |
| Description | Applications of proton transfer reaction chemistry for the detection of solid and liquid explosives |
| Amount | £96,168 (GBP) |
| Funding ID | IRC2010/ITT122 |
| Organisation | Home Office |
| Sector | Public |
| Country | United Kingdom |
| Start | 01/2011 |
| End | 06/2014 |
| Description | European Commission (EC) |
| Amount | £3,445,035 (GBP) |
| Funding ID | 287382 |
| Organisation | European Commission |
| Sector | Public |
| Country | European Union (EU) |
| Start | 06/2012 |
| End | 05/2016 |
| Description | European Commission (EC) |
| Amount | £3,445,035 (GBP) |
| Funding ID | 287382 |
| Organisation | European Commission |
| Sector | Public |
| Country | European Union (EU) |
| Start | 06/2012 |
| End | 05/2016 |
| Description | Applications of proton transfer reaction chemistry for the detection of solid and liquid explosives |
| Organisation | Ionicon Analytik GmbH |
| Country | Austria |
| Sector | Private |
| PI Contribution | To develop PTR-MS technology for threat agent detection. As a result of this collaboration we have had access to state of the art instrumentation based on soft chemical ionisation processes and drift tube technology. |
| Start Year | 2010 |
| Description | Proton Ionization Molecular Mass Spectrometry |
| Organisation | Kore Technology Ltd |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Development of PTR-MS instrumentation for various applications and training of early stage researchers. KORE Analytik Ltd is the UK's leading manufacturer of PTR-ToF_MS instruments. The company will provide short term visits at appropriate times for early stage researchers on the ITN programme and will also fully contribute to the network training programmes. |
| Start Year | 2012 |
| Description | Bre4th |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | Yes |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | A core team of two multimedia artists (Terry Braun and Gabi Braun) and Chris Mayhew's research group collaborated in new ways of producing dynamic computer visualisations and sonifications of disease diagnosis via breath. By concentrating on breath we could have live demonstrations of PTR-MS analytical technology. A major live art/physics display/show took place during a 3-week period in February 2010 in the Science Museum London at the Dana Centre. A series of participatory public events exploring the detection of chemicals in human breath technology were prepared. (Please see http://beearts.org.uk/BRE4TH/ for more details). A SERIES OF FUN EVENTS AT THE SCIENCE MUSEUM DANA CENTRE IN LONDON EXPLORING THE ART OF NEW TECHNOLOGIES THAT ENABLE YOU TO 'SEE' AND 'HEAR' THE HIDDEN SECRETS IN THE AIR THAT WE BREATHE! |
| Year(s) Of Engagement Activity | 2009 |
| URL | http://www.beearts.org.uk/BRE4TH/techniques.html |