Method and system of identifying a sample by analyising a mass spectrum by the use of a bayesian inference technique
A method and system for the identification and/or characterization of properties of a sample using mass spectrometry. The method involves producing a measured spectrum of data from a sample using a mass spectrometer, deconvoluting the measured spectrum of data by Bayesian inference to produce a family of plausible deconvoluted spectra of data, inferring an underlying spectrum of data from the family of plausible deconvoluted spectra of data and using the underlying spectrum of data to identify and/or characterize the sample.
1. A method of identifying or characterising at least one property of a sample, the method comprising the steps of:
a. producing at least one measured spectrum of data from a sample using a mass spectrometer;
b. deconvoluting the at least one measured spectrum of data by Bayesian inference to produce a family of plausible deconvoluted spectra of data;
c. inferring an underlying spectrum of data from the family of plausible deconvoluted spectra of data; and
d. using the underlying spectrum of data to identify or characterise at least one property of the sample.
2. The method of claim 1 further comprising the step of identifying the uncertainties associated with underlying spectrum of data from the family of plausible deconvoluted spectra of data.
3. The method of claim 1 wherein the deconvolution step further comprises assigning a prior using a procedure comprising at least two steps.
4. The method of claim 3 , wherein the procedure comprises first assigning a prior to the total intensity and then modifying the prior relative to the proportions for specific charge states.
5. The method of claim 1 , wherein the deconvolution step further comprises the use of a nested sampling technique.
6. The method of claim 1 , wherein the procedure comprises varying predicted ratios of isotopic compositions to identify or characterise the at least one property of the sample.
7. The method of claim 1 further comprising comparing at least one characteristic of the underlying spectrum of data with a library of known spectra to identify or characterise the at least one property of the sample.
8. The method of claim 1 further comprising comparing at least one characteristic of the underlying spectrum of data with candidate constituents to identify or characterise the at least one property of the sample.
9. The method of claim 1 , wherein the deconvolution step comprises the use of importance sampling.
10. The method of claim 1 , wherein the at least one measured spectrum of data comprises electrospray mass spectral data.
11. The method of claim 1 , further comprising recording a temporal separation characteristic for the at least one measured spectrum of data and storing the underlying spectrum of data with the recorded temporal separation characteristic on a memory means.
12. The method of claim 1 , further comprising recording a temporal separation characteristic for the at least one measured spectrum of data and using the recorded temporal separation characteristic to identify or characterise the or a further at least one property of the sample.
13. A system for identifying or characterising a sample, the system comprising:
a. a mass spectrometer for producing at least one measured spectrum of data from a sample;
b. a processor configured or programmed or adapted to deconvolute the at least one measured spectrum of data by Bayesian inference to produce a family of plausible deconvoluted spectra of data and infer an underlying spectrum of data from the family of plausible deconvoluted spectra of data; and
wherein the processor is further configured or programmed or adapted to use the underlying spectrum of data to identify or characterise at least one property of the sample.
14. The system of claim 13 further comprising a first memory means for storing the underlying spectrum of data.
15. The system of claim 14 further comprising a second memory means on which is stored a library of known spectra.
16. The system of claim 15 , wherein the processor is further configured or programmed or adapted to carry out a method according to any one of claims 1 to 12 .
17. A computer program element comprising computer readable program code means for causing a processor to execute a procedure to implement the method of claim 1 .
18. The computer program element of claim 17 embodied on a computer readable medium.
19. A computer readable medium having a program stored thereon, where the program is to make a computer execute a procedure to implement the method of claim l.
20. A mass spectrometer suitable for carrying out, or specifically adapted to carry out, a method according to claim 1 .
21. A retrofit kit for adapting a mass spectrometer to provide a mass spectrometer suitable for carrying out, or specifically adapted to carry out, a method according to claim 1 , the kit comprising a computer program element including computer readable program code means for causing a processor to execute a procedure to implement that method.
22. The retrofit kit of claim 21 , wherein the computer program element is embodied on a computer readable medium.
23. A mass spectrometer comprising the program element of claim 17 .
24. A mass spectrometer comprising a computer readable medium according to claim 19 .