**1. Introduction**

The pyrolysis technique has been extensively used for many years as an analytical technique in which large molecules are degraded into smaller volatile species using

solely thermal energy under an oxygen-free environment. The coupling of this thermal energy as a laser source (pyrolyzer), an optical microscope, and the gas chromatographic tandem Mass Spectrometry (GC/MSMS) system compound a hyphenated analytical technique called Laser Micropyrolysis GC/MSMS (LmPy-GC/ MSMS). This coupling contributes to improving the analytical processes during sample characterization, and it is considered a useful tool for the determination of the composition or structure of the organic compounds whether in individual components or samples of complex mixtures.

Molecular information on organic fossils in samples such as coals [1–4], source rocks [5–7], kerogen [8–14]; oil shales [4, 15, 16], and synthetic organic polymers [17, 18] had been successfully afforded by LmPy-GC/MSMS among existing pyrolysis technique, proving to be an excellent way to characterize the chemical composition of heterogeneous materials.

The analytical temperature is a crucial variable in pyrolysis techniques, being low temperatures are not analytically useful for efficient degradation while high temperatures are more efficient for breaking molecule bonds, however, caution needs to be taken not to destroy the molecule. In this sense selecting the adequate temperature at which macromolecules can be degraded in a wide array of products has great significance.

In the LmPy-GC/MSMS system is not possible to control the temperature. This laser provides a thermal flux as high as 1000°C/s which is enough to heat the sample in a very short time. The combination of high temperature and short time minimizes secondary pyrolysis reactions when laser pyrolysis is used and generates pyrolysis fragments characteristic of the original sample. This short-duration laser beam energy (1000°C/s) is collimated and coherent allowing the spread of very large amounts of thermal energy on a specific area of slim dimension, enabling the thermal cleavage of samples (e.g., isolated components or a macromolecule) into smaller components which in turn are analyzed by GC/MSMS.

The collimated and coherent laser irradiation allows focus on tiny or small areas of heterogeneous materials, which enables analysis of non-volatile, thermally labile components at the microscopic level. The focused and irradiated area can be less than 100 μm, using the appropriate lenses in the optical microscope. These microscopic areas permit isolated analysis of individual components into complex mixtures. In conclusion, the LmPy-GC/MSMS shows great potential to improve the understanding of organic composition in heterogeneous materials as well as isolated organic-walled microfossils.

Several authors [15, 16, 18–20] lay emphasis on their research on instrumental development and list diverse factors to be considered, such as (i) little knowledge about laser-material interactions; (ii) limitations in the sensibility of chromatographic techniques needed for products with low concentrations; (iii) need for interdisciplinary skill; (iv) possible interfacing-instruments difficulties; (v) the issue that all samples are not compatible with laser radiation to produce pyrolysis products and; (vi) the financial expense due to the acquisition of diverse instruments. On the other hand, the applicability of the LmPy-GC/MSMS as well as the use of other detection methods, such as NMR or FTIR, to characterize the molecular composition of distinctive organic samples, have been studied by many authors.

The kerogen of the Ordovician Estonian Kukersite sample was analyzed by Derenne et al. using spectroscopic NMR and FTIR, and off-line and flash pyrolytic methods [5]. Stout and Hall assayed two synthetic organic polymer samples by LmPy-GCMS [17] while Arouri et al. characterized Acritarch specimens [8],

*Using LmPy-GC/MSMS to Molecular Characterization of Organic Components… DOI: http://dx.doi.org/10.5772/intechopen.114360*

Chitinozoan specimens from Silurian marine rocks were studied by Jacob et al. [11], and, Silva et al. compared the chemical composition of *Botryococcus braunii* and *Graphelmis prisca* microfossils [14]. Greenwood et al. demonstrated the credibility of the LmPy-GC/MS through the analysis of micro-sized quantities of various organic fossils [4, 6, 9, 21, 22]. Yoshioka and Takeda (2004) use IR laser micropyrolysis to analyze organic compounds in three macerals of an immature, sub-bituminous coal [23]. In addition, comparative studies between Curie-point pyrolyzer coupled to GC/ MS (CP-Py-GC/MS) and LmPy-GC/MSMS were performed by Saundouk-Lincke et al. [12, 13] and Dutta et al. [10].

The favorable comparison of laser-derived molecular data with corresponding data from traditional methods, reported above, suggests that pyrolysis methods are suitable for molecular characterization of organic macromolecules. In addition, these researchers have also evidenced the possibility of a couple of combinations of LmPy-GC/MSMS with other micro or macroscale spectroscopic methods such as NMR, CP-Py, or FTIR. All of these results are useful to improve knowledge and understanding, allowing individual analysis of an isolated particle or smaller components inside complex mixtures in heterogeneous organic materials.
