Mass Spectrometry is an method which can determine the composition of samples. It is a highly effective method for determining the structures of molecules, as well as which elements the sample is composed of. Qualitative and quantitative analysis of the composition of mixtures can be determined as well.
A video that explains this method briefly, but well, can be found at: http://www.youtube.com/watch?v=J-wao0O0_qM. As it explains, depending on the sample properties, the manner in which the sample is processed is different. Volatile substances, or substances which readily vaporize, are simpler to analyze than those that are non-volatile.
One of the pros of this technique is that relatively little sample is needed in order to obtain accurate results. A setback is that many of the instruments round the mass of the molecules and ions, so similar molecules may look the same. Depending on the molecule and the ions it most commonly forms, the ion peaks can help determine which of the possible molecules is being analyzed. The Mass Spectrometer yields graphs showing the initial molecule as well as the ions that are formed when the molecule is bombarded with electrons. Depending on the relative abundances of the ions, the likely structures will be narrowed down. Some Mass Spectrometers are more accurate than others and can further indicate the ionic masses.
One of the types of Mass Spectrometry is Electron-Impact Mass Spectrometry. For this method, a sample is brought to a high temperature. This produces a molecular vapor. The gas is then bombarded with a beam of electrons with high energy to ionize the sample. This method is not very efficient; only about 1 of 1,00,000 molecules are ionized in this manner.
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