Processing of mass spectral data

While it is true that in many cases the quality of data acquired during analysis is directly proportional to the quality of the result that may be obtained, it is also true that in many cases the power of modem computer systems attached to analytical equipment of all sorts can be used to provide better results than might be thought possible from a cursory examination of the raw data. Even when chromatography is used to separate the components of a mixture and simplify the job of the analyst, the computer may still allow information hidden in the vast amount of data generated to be extracted. 

A full description of a mass spectrometry data system is beyond the scope of this present text, but its major roles may be considered to be the following  

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Historically, ions for mass analysis were produced by electron impact, in Ihis process, the sample is brought to a temperature high enough to produce a molecular vapor, which is then ionized by bombarding the resulting molecules with a beam of energetic electrons. Despite certain disadvantages, this technique is still of major importance and is the one on which many libraries of mass spectral data are ba,scd. 

Busch et al. (76) first described a custom-built secondary ion mass spectrometer for the analysis of TLC chromatograms in 1985. The instrument has been through several revisions since the initial prototype was constructed, including changes in the size of the chromatogram that could be accommodated within the vacuum chamber, the accuracy of sample placement for acquisition of spatial images, and in the data system used to control the scanning experiment and process the mass spectral data. 

This behavior is not consistent with mass spectral observations, although the enthalpies of reaction (18) in vapor over LaCla, CeCla, TbCla, and LuCla are rather close to the values obtained by processing the mass spectral data. 

Apart from the actual acquisition of the mass spectrum and its subsequent display or printout, the raw mass spectral data can be processed in other ways, many of which have been touched on in other chapters in thi.s book. Some of the more important aspects of this sort of data manipulation are explained in greater detail below. 

To appreciate the ways in which mass spectral data may be processed to utilize fully the selectivity and sensitivity of the mass spectrometer as a detector for HPLC. 

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