I am trying to know about some unknown mass peak from my sample's TIC, but how to approach for it I don't know? Can someone suggest me some ways to do it?
You can either purchase a MS library that you can use to search for your unknowns, or purchase Fred McLaferty's book of Interpretation of Mass Spectra.
To expand on Mitch's comment, the latest US EPA method 8270E (SW-846 Update VI 8270E - 32 Revision 6 June 2018 - SEMIVOLATILE ORGANIC COMPOUNDS BY GAS CHROMATOGRAPHY/MASS SPECTROMETRY) gives a good summary of what you can do for an "unknown" compound in a TIC.
"11.6.2 Tentative Identification - For samples containing components not associated with the calibration standards, a library search may be made for the purpose of tentative identification. The necessity to perform this type of identification will be determined by the purpose of the analyses being conducted. For example, the Resource Conservation and Recovery Act (RCRA) permit or waste delisting requirements may require the reporting of non-target analytes. Data system library search routines should not use normalization routines that would misrepresent the library or unknown spectra when compared to each other. Only after visual comparison of sample spectra with the library searches may the analyst assign a tentative identification. Guidelines for tentative identification are:
(1) Major ions in the library reference spectrum (ions greater than 10% of the most abundant ion) are present in the sample spectrum at similar relative intensities.
(2) The molecular ion in the library reference spectrum is present in the sample spectrum. If the molecular ion is not present, carefully review library matches in order to avoid misidentification.
(3) Major ions present in the sample spectrum but not in the reference spectrum are reviewed to determine whether they may be contributed by co-eluting compounds.
(4) Ions present in the reference spectrum but not in the sample mass spectra are reviewed for unintended subtraction. Data system library reduction programs can sometimes create these discrepancies.
(5) Mass spectral library search algorithms typically assign a match factor to the peak identity based on comparison of an unknown mass spectrum to library spectra. For spectra meeting the above conditions, match factors greater than 0.8 (80%) may be considered confirming evidence. Where a known limitation in data collection is identified, e.g., the presence of an incompletely resolved spectral interference, a lower match factor may be considered confirmatory. For multiple library spectra with similar match factors (e.g., for hydrocarbons with low abundance molecular ions, or structural isomers), the tentative identification assigned to the unknown may be better represented as a more generic structure (e.g., unknown hydrocarbon, C4 benzene structural isomer). See Reference 18 in Sec. 16 for more information."
You can make a very rough determination of an approximate concentration level of your "unknown" by the compound's peak area from the TIC compared to other "known" compounds in the same TIC, but you must be scanning across a wide mass range (like 35-500u). If you do this remember that the "unknown" amount could be >5-1000% of the calculated value. It the "unknown" has a similar structure to your "knowns" the error will be less...
Are you dealing with GC-MS or LC-MS spectra ? In fact, it is not exactly the same way to interpret mass spectra. There is no library for LC-MS spectra unless your are looking for metabolomics.
Retrieving data ...