Feature selection in mass spectral data
The present invention provides, inter alia, methods of analyzing mass spectral data. In some embodiments, the methods can be used for differential profiling of samples, such as comparing a sample comprising a compound and a sample comprising metabolites of the same compound. The methods can also be used to identify and isolate biomarkers. Systems for performing the methods, as well as computer-readable media for performing the methods, are also described.
1. A method of analyzing mass spectral data obtained from a sample, comprising:
dividing the mass spectral data into feature groups, wherein each of said feature groups relates to a compound; and
filtering the data based on properties selected from the group consisting of retention time, mass, isotope pattern, charge state, abundance, mass defect, and number of ions.
2. The method of claim 1 , wherein said dividing is performed based on retention time, mass to charge ratio, isotope clustering, adduct formation, dimer formation, and trimer formation of spectral peaks.
3. The method of claim 1 further comprising comparing the properties of at least one feature group to the properties of a known material to identify one or more components in the sample.
4. The method of claim 1 , wherein the sample is a biological sample.
5. A method for differential profiling multiple sets of mass spectral data, wherein each set of the mass spectral data is obtained from a distinct sample, the method comprising:
(a) analyzing each set of mass spectral data according to the method of claim 1 ;
(b) comparing the results of step (a) from different samples to identify compounds that are present in different amounts between or among the samples.
6. A computer-readable medium comprising executable instructions to perform the method of claim 1 .
7. A system comprising the computer-readable medium of claim 6 .
8. The system of claim 7 further comprising a mass spectrometer.
9. The system of claim 8 further comprising at least one liquid chromatography column.
10. The system of claim 8 further comprising at least one gas chromatography column.
11. The system of claim 8 further comprising at least one capillary electrophoresis apparatus.
12. The system of claim 8 wherein the mass spectrometer comprises an ion source selected from the group consisting of electrospray, matrix assisted laser desorption (MALDI), and photoionization ion sources.
13. The system of claim 8 wherein the mass spectrometer comprises a mass analyzer selected from the group consisting of quadrupole, time-of-flight, ion trap, and fourier transform-ion cyclotron resonance (FT-ICR) mass analyzers.
14. A method of comparing the compositions of multiple samples, comprising:
(a) separating at least part of the components in each sample;
(b) analyzing the separated components in each sample with a mass spectrometer to generate a mass spectral data set for each sample;
(c) recording the multiple mass spectral data sets; and
(d) analyzing each of the mass spectral data sets according to the method of claim 1 and comparing the results from said multiple samples.
15. The method of claim 14 , wherein said dividing is performed based on retention time, mass to charge ratio, isotope clustering, adduct formation, dimer formation, and trimer formation of spectral peaks in the mass spectral data.
16. The method of claim 14 further comprising comparing the properties of at least one feature group to the properties of a known material to identify one or more components in each of the samples.
17. The method of claim 14 , wherein the multiple samples are biological samples.
18. The method of claim 14 , wherein the at least part of the components are separated in step (a) by liquid chromatography.
19. A method for differential profiling multiple sets of mass spectral data, wherein each set of the mass spectral data is obtained from a distinct sample, the method comprising:
(a) dividing the mass spectral data from each sample into feature groups, each feature group relating to a compound, wherein said dividing is performed based on retention time, mass to charge ratio, and optionally at least one property selected from the group consisting of isotope clustering, mass, adduct formation, dimer formation, and trimer formation; and
(b) comparing the results of step (a) from different samples to identify compounds that are present in different amounts between or among the samples.
20. A computer-readable medium comprising executable instructions to perform the method of claim 19 .