Interpretation differs for atomic samples and molecular samples.

For atoms - Based on Mass to charge ratio (M/z) values identify the atoms. Also need to take into account the presence of isotopes and  their natural abundance.

For molecules - Based on the M/z of molecular ion peak and the fragmentation pattern one identifies molecules. You can compare the spectra with the known compounds present in databases, if it has already been studied. Optimum fragmentation is needed to see the molecular ion peak, otherwise one may miss it.

Mr. Raghavan,

First, the results from MS methods are not so trivial for interpretation, particularly aiming to obtain structural and quantitative information, not only a qualitative one reflecting in mind a determination of molecular ion. Furthermore I can deduce from your question that you have reflected in mind soft ionization MS methods, not hard - ones. Very useful in the context of your questions I personally have found the following 4 books:

1. J. Gross, Mass Spectrometry, 2nd Ed. 2010, Springer Verlag, Heidelberg, pp. 1 - 753.

Despite the fact that this has been denoted as a "textbook" it has rather a monography style, where after each chapter are shown comprehensive reference section, but by other authors.

This book has briefly recognized with the fundamentals to each of the MS methods, in parallel giving examples for interpretation of the spectra, however, a small number. As an attachment, page 1 it is shown a scanned version of two pages, to illustrate the style of writing and illustrative material of MS data.

2. K. Busch, G. Glish, S. McLuckey, Mass spectrometry/Mass spectrometry, VCH Publisher, 1988, pp. 1 - 333

This book brings light to tandem MS-techniques which are indispensable ones for structural analysis. They are only scarce mentioned in book shown in point 1 (Attachment, page 2).

3. Gerhard Spiteller, Massenspektrometrisch Strukturanalyse organischer Verbindungen, 1966, Verlag Chemie, Weinheim, pp. 1 - 534.

By contrast to book shown in page 1, this book as textbook provides more useful information for the practical purposes for interpretation, but only of organics. The methods and techniques are rather briefly shown. But the mechanisms of fragmentation and ion formations are comprehensively discussed (Attachment, page 3).

4. Margot Spiteller, Gerhard Spiteller, Massenspektrensammlung von Losungsmitteln, Verunreinigungen, Saeulenbelegmaterialien und einfachen aliphatischen Verbindungen, Springer Verlag, 1973, Wien, pp.1 - 170.

Particularly useful book for interpretation for MS of organics, giving short description to mechanisms to each class of organics (Hydrocarbons, ROH, ROR', R-(C=O)-R'(H), RCOOH, RCOOR', N- and S-containing organics, aromatics) with fragmentation schemes and assignment of a set collected molecular objects to each organic class (Attachment, page 4). However, there are not included heterocyclics.

There are few book for analysis specifically of peptides and alkaloids other naturally occurring products as well as, but there is not so easy to deduce the mechanism, of fragmentation due to the complexity of the molecular structure. Particularly proteomics is shown in the book listed under point 2, as well.

Thank you bojidarka madam... It somuch valuable guidance to given I will read this book and attached files then clarification my doubts 

Thank you...