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HPLC is a technique used for fractionating, purification and determining the size of molecules. When separation is based on molecule size, these techniques are referred to as High Performance Size Exclusion Chromatography (HPSEC), using specific chromatographic columns and known size standards (dextran or pullulan). The detectors employed were refraction index (RI) [14, 21, 75, 78] and Multi-angle Laser Light Scattering (MALLS) [21, 75, 78]. HPAE-PAD was also reported, consisting of a separation technique based on the charge of molecules and useful for separating neutral molecules.

Gas Chromatography is another widely employed technique suitable for analyzing volatile compounds. Other commonly used analytical techniques include Infrared Spectroscopy (IR), Nuclear Magnetic Resonance (NMR), and Mass Spectrometry (MS). These methods can be used to investigate the structure of a compound or to identify a compound based on the specific signatures of a chemical bond or group present.

UV/Vis studies were also found as a complementary technique for characterizing compounds, in which a marker such as chromophore was used. Recently, using a microarray-based technique, it was possible to study the relative abundance, and interactions between hundreds or thousands of molecules simultaneously, using very small volumes of A. vera extracts of different species (Table 1.2).