Spectrometric analysis
A method of spectrometric analysis comprises obtaining one or more sample spectra for an aerosol, smoke or vapour sample. The one or more sample spectra are subjected to pre-processing and then multivariate and/or library based analysis so as to classify the aerosol, smoke or vapour sample. The results of the analysis are used for various surgical or non-surgical applications.
1. A method of spectrometric analysis comprising:
obtaining one or more sample spectra for an aerosol, smoke or vapour sample;
pre-processing the one or more sample spectra, wherein pre-processing the one or more sample spectra comprises a deisotoping process, and wherein the deisotoping process comprises identifying one or more additional isotopic peaks in the one or more sample spectra and reducing or removing the one or more additional isotopic peaks in or from the one or more sample spectra; and
analysing the one or more pre-processed sample spectra so as to classify the aerosol, smoke or vapour sample, wherein analysing the one or more sample spectra comprises multivariate and/or library-based analysis.
2. A method as claimed in claim 1 , wherein the deisotoping process comprises an iterative process, optionally comprising iterative forward modelling, and/or wherein the deisotoping process comprises a probabilistic process, optionally a Bayesian inference process.
3. A method as claimed in claim 1 , wherein the deisotoping process comprises a Monte Carlo method.
4. A method as claimed in claim 1 , wherein the deisotoping process comprises one or more of: nested sampling; massive inference; and maximum entropy.
5. A method as claimed in claim 1 , wherein the deisotoping process comprises deconvolving the one or more sample spectra with respect to theoretical mass and/or isotope and/or charge distributions.
6. A method as claimed in claim 5 , wherein the theoretical mass and/or isotope and/or charge distributions are derived from known and/or typical and/or average properties of a class of aerosol, smoke or vapour sample.
7. A method as claimed in claim 1 , wherein the deisotoping process comprises generating a set of trial hypothetical monoisotopic sample spectra.
8. A method as claimed in claim 7 , wherein the set of trial hypothetical monoisotopic sample spectra is generated using one or more probability density functions for mass, intensity, charge state, and/or number of peaks, for a suspected class of sample to which the one or more sample spectra relate.
9. A method as claimed in claim 7 , wherein the deisotoping process comprises generating a set of modelled sample spectra having isotopic peaks from the set of trial hypothetical monoisotopic sample spectra.
10. A method as claimed in claim 9 , wherein the set of modelled sample spectra is generated using average isotopic distributions for the suspected class of sample to which the one or more sample spectra relate.
11. A method as claimed in claim 7 , wherein the deisotoping process comprises deriving a likelihood for the one or more sample spectra given each trial hypothetical monoisotopic sample spectrum.
12. A method as claimed in claim 11 , wherein the deisotoping process comprises deriving a likelihood for the one or more sample spectra given each trial hypothetical monoisotopic sample spectrum by comparing each modelled sample spectrum to a sample spectrum.
13. A method as claimed in claim 11 , wherein the deisotoping process comprises iteratively re-generating a trial monoisotopic sample spectrum having the lowest likelihood until a maximum likelihood is reached for all the trial monoisotopic sample spectra.
14. A method as claimed in claim 1 , wherein the deisotoping process comprises deriving a deisotoped spectrum.
15. A method as claimed in claim 13 , wherein the deisotoping process comprises deriving a deisotoped spectrum from a final set of trial monoisotopic sample spectra.
16. A method as claimed in claim 1 , wherein obtaining the one or more sample spectra comprises generating the aerosol, smoke or vapour sample using a sampling device.
17. A method as claimed in claim 16 , wherein the sampling device comprises one or more ion sources selected from the group consisting of: (i) a rapid evaporative ionisation mass spectrometry (“REIMS”) ion source; (ii) a desorption electrospray ionisation (“DESI”) ion source; (iii) a laser desorption ionisation (“LDI”) ion source; (iv) a thermal desorption ion source; (v) a laser diode thermal desorption (“LDTD”) ion source; (vi) a desorption electro-flow focusing (“DEFFI”) ion source; (vii) a dielectric barrier discharge (“DBD”) plasma ion source; (viii) an Atmospheric Solids Analysis Probe (“ASAP”) ion source; (ix) an ultrasonic assisted spray ionisation ion source; (x) an easy ambient sonic-spray ionisation (“EAST”) ion source; (xi) a desorption atmospheric pressure photoionisation (“DAPPI”) ion source; (xii) a paperspray (“PS”) ion source; (xiii) a jet desorption ionisation (“JeDI”) ion source; (xiv) a touch spray (“TS”) ion source; (xv) a nano-DESI ion source; (xvi) a laser ablation electrospray (“LAESI”) ion source; (xvii) a direct analysis in real time (“DART”) ion source; (xviii) a probe electrospray ionisation (“PEST”) ion source; (xix) a solid-probe assisted electrospray ionisation (“SPA-ESI”) ion source; (xx) a cavitron ultrasonic surgical aspirator (“CUSA”) device; (xxi) a focussed or unfocussed ultrasonic ablation device; (xxii) a microwave resonance device; and (xxiii) a pulsed plasma RF dissection device.
18. A method of spectrometric analysis comprising:
obtaining one or more sample spectra for an aerosol, smoke or vapour sample, wherein obtaining the one or more sample spectra comprises causing the aerosol, smoke or vapour sample to impact upon a collision surface located within a vacuum chamber of a mass and/or ion mobility spectrometer so as to generate a plurality of analyte ions;
pre-processing the one or more sample spectra, wherein pre-processing the one or more sample spectra comprises a deisotoping process; and
analysing the one or more pre-processed sample spectra so as to classify the aerosol, smoke or vapour sample, wherein analysing the one or more sample spectra comprises multivariate and/or library-based analysis.
19. A spectrometric analysis system comprising:
control circuitry arranged and adapted to:
obtain one or more sample spectra for an aerosol, smoke or vapour sample;
pre-process the one or more sample spectra, wherein pre-processing the one or more sample spectra comprises a deisotoping process, and wherein the deisotoping process comprises identifying one or more additional isotopic peaks in the one or more sample spectra and reducing or removing the one or more additional isotopic peaks in or from the one or more sample spectra; and
analyse the one or more pre-processed sample spectra so as to classify the aerosol, smoke or vapour sample, wherein analysing the one or more sample spectra comprises multivariate and/or library-based analysis.