Part 1: Imaging Spectroscopy: From air quality investigations to healthcare applications

Transcription

1 Part 1: Imaging Spectroscopy: From air quality investigations to healthcare applications Part 2: Chemical Ionisation Reaction Mass Spectrometry (CIR-MS) for Breath Analysis Research 12 th March 2009 Roland Leigh

2 The Global picture Poor quality air is thought to result in more than 32,000 premature deaths in the UK each year alone. (China: 300, ,000 p.a.) Air pollution reduces life expectancy by an average of almost nine months across the European Union. Every European takes on average half a day off sick a year due to illnesses linked to air pollution - costing the European economy more than 80bn euros ( 55bn) p.a.(euro. Commission report ) PM10 Concentration in main global cities source WHO 2006

3 NO 2 in the urban atmosphere NO 2 is one of the best indicators of air quality. - DEFRA At relatively high concentrations, nitrogen dioxide causes inflammation of the airways. There is evidence to show that long-term exposure to nitrogen dioxide may affect lung function and that exposure to nitrogen dioxide enhances the response to allergens in sensitized individuals. In addition, nitrogen dioxide contributes to the formation of ozone and of secondary particles and is implicated in acidification and eutrophication. Nitrogen Dioxide in the United Kingdom, Air Quality Expert Group, p1, 2003)

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7 View of entrance slit and CCD image Zenith 200μm 15 o 10 o 400μm 5 o 0 o

8 MTG OMI CAPACITY Imaging Spectrometer Development at the University of Leicester Wavelength (nm) Target Species Signal-to-Noise Wavelength (nm) Target Species Signal-to-Noise Stratospheric O3 Col O3 profile O3 column Total & Trop O3, HCHO SO2, HCHO, O4, OClO AAI, SSA, AOT NO O NO2, O3, CTH Spatial Zoom O3 profile 45 Wavelength (nm) Target Species Signal-to-Noise O3 column HCHO 1050 O3 profile OClO SO NO Tropospheric O O O HCHO 2500 Global View?

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11 26 ppbv or 0.73 kg NO 2 Proven ability to identify and quantify emission sources within an urban environment.

12 Imaging Spectroscopy Applications Direct: Air quality across urban areas, monitoring emissions and concentrations of pollutants across urban areas, airports, harbours etc. Example medical application: Measure the air quality across a city by postcode, and correlate with respiratory-related hospital admissions Leading to the development of warning systems. Indirect: Indoor air quality monitoring, whole body spectral imaging, other?? A B C

13 The Development of Chemical Ionisation Reaction Mass Spectrometry (CIR-MS) for Breath Analysis Research Paul Monks and Kerry Willis

14 Breath Analysis Exhaled Breath Nitrogen 78 % Oxygen 16 % Carbon Dioxide 4 % VOCs % VOCs: Trace Breath Compounds Inorganics: Alkanes Aldehydes Nitric oxide Alkenes Ketones Ammonia Alcohols N-/S-compounds Exhaled breath Bulk component: nitrogen, oxygen, carbon dioxide and water vapour Small fraction which contains hundreds of trace volatile organic compounds (VOCs) and small inorganic molecules in the ppm - ppb range VOCs can be produced anywhere in the body as a result of physiological and pathological processes The effect of disease on the body causes changes in VOC composition which may be reflected in exhaled compounds On the basis that VOCs in breath are representative of VOCs in blood and therefore processes occurring in the body, breath analysis may become a non-invasive tool for use in clinical practice

15 Breath Analysis Advantages Non-invasive procedure No risk allowing for repeated use Suitable for people of all ages and conditions Quick to perform/immediate results (with the right analytical technique) Applications: Complimentary tool for diagnosis Monitor for disease progression or course of therapy Research has advanced in last 20 years Many studies published but only recently recognised the need to pull findings together Resulted in the International Association of Breath Research (IABR) The current focus: What is normal? How do VOCs vary in diseased states - can markers for particular conditions be identified? A new technique for breath research

16 CIR-TOF-MS Chemical Ionisation Reaction Time-of-Flight Mass Spectrometry

17 CIR-TOF-MS Chemical Ionisation Ionisation of a sample molecule by reaction with a primary/reagent ion - hydronium ion (H 3 O + ) These H 3 O + ions react with sample VOCs by proton transfer: VOC + H 3 O + VOCH + + H 2 O only if PA(VOC)>PA(H 2 O) Excludes the bulk components of breath Soft ionisation: little fragmentation, single peaks - ideal for complex mixtures such as breath

18 CIR-TOF-MS Time-of-Flight Analysis Lighter ions travel quicker than heavier ions Flight time mass Suited to breath research as makes simultaneous measurements over a broad mass range

19 Breath Sampling Apparatus Breath collection apparatus Wide-bore components low resistance Disposable mouthpiece and bacterial filter infection control Digital volume transducer records volume and flow rate measurements A sample of breath is drawn as it passes through the apparatus Heated to 40 C prevents condensation Disposable mouthpiece & bacterial filter Apparatus heated to 40 C Digital volume transducer Portion of breath sampled by instrument Off-line sampling Tedlar bags (for short term containment) Attach mouthpiece and filter to bag inlet

20 Volume (ml) Breath Sampling Protocol First portion of breath is dead space air Air filling the airways Never reaches the alveoli to take part in gas exchange with the blood Breath collection Single vital capacity breath Total amount of air which can be exhaled after a maximum inhalation Bigger portion of alveolar air Quick procedure Collect data every second for 30-60s Breath usually <10s Mass range up to 200 Da Tidal Collection vs Single Breath Collection EXHALATION Tidal Single INHALATION Time (seconds)

21 Volume (ml) Signal (ncps) Signal Signal m/z 59 (ncps) Typical CIR-MS Breath Spectrum Reagent ion signals 1.0E E E+05 H 3 O + 2.6E+05 H 3 O + H 2 O 8.0E E E E E E+04 Time 2.0E E E m/z E E EXHALATION volume measured by transducer m/z 59 measured by CIR-MS 9.E+04 8.E+04 7.E+04 6.E+04 3.E INHALATION 2.E+04 1.E Time (s) 0.E+00

22 Calibration Results Concentration (ppb) Concentration (ppb) Concentration (ppb) Concentration (ppb) Calibration 100% relative humidity 250 Methanol 400 Acetone ammonia acetone ethanol methanol isoprene Sensitivity (ncps/ppb) ammonia 59.1 methanol 66.7 acetonitrile acetaldehyde 94.8 ethanol 0.5 propanol formic acid 0.9 acetaldehyde acetone ppb Time (seconds) Dimethyl Sulphide 23 ppb ppb Time (seconds) Isoprene 281 ppb acetic acid dimethyl sulphide Concentration 89.2 (ppb) Spanel et al., J. Breath Res. 1 (2007) isoprene pentene Time (seconds) Time (seconds)

23 [Ethanol] (ppb) [Acetaldehyde], [Acetic Acid] (ppb) Breath Alcohol Experiments Ethanol metabolism well defined process Good proof of principle experiment to show monitoring of processes occurring in the body ETHANOL ACETALDEHYDE ACETIC ACID Initial high concentration of ethanol in the mouth Peaks in blood ethanol and acetaldehyde concentrations ethanol acetaldehyde acetic acid? Baseline Levels Time (minutes)

24 Intensity (ncps) Intensity (ncps) Asthma Study Asthma is a chronic inflammatory disorder of the airways Affects ~ 5 million people in the UK Aim: To look for exhaled markers that would indicate what type of inflammation is present for correct administration of antiinflammatory treatment 68 Patients - asthmatics, COPDs, healthy controls 1.80E+05 acetone 6.00E+03 acetonitrile 1.50E E E E E E+04 Diabetic Healthy Subject Healthy Subject 3.00E E+03 Smoker Non-smoker Non-smoker 3.00E E E E Time (s) Time (s)

25 normalised counts normalised counts Bacteria Headspace normalised counts normalised counts Haemophilus influenzae Streptococcus pneumoniae 4.0E E E E E E E E E E E E m/z 2.5E E E E E E m/z Staphylococcus aureus Pseudomonas aeruginosa 4.0E E E E E E E E E E E E m/z 2.5E E E E E E m/z

26 The Future Future work for CIR-MS 2 studies tuberculosis and cancer Breath test as a screening tool? The future for breath analysis Research will continue on expensive analytical instruments but the exhaled markers identified in these studies will allow for specific sensors to be designed Portable and cheaper Breath analysis in clinical practice much more realistic Routine use in doctors surgery or even personal monitors

27 For More information: Air Quality, Imaging Spectroscopy Please go to Or » Roland Leigh Paul Monks For Breath Analysis Please » Paul Monks Thank you for your attention