The most widely used analytical technologies for bioenergy chains are described

below:

• Titrimetry or volumetry determination of ions, especially by means of compl- exation reactions, neutralization or oxidation-reduction, resulting in the color change of the solution; this is the case of cation determination for feedstock and biofuels quality control (Artiga et al. 2005);

• Gravimetry determination of ions through complexation reactions, redox and precipitation, by means of drying and weighing the compound formed/ solid; this is the case of anion determination in effluent. For suspended sol­ids, it proceeds only to water evaporation and subsequent weighing of the solid

obtained. Gravimetry can be applied for feedstock and biofuels quality control (Seixo et al. 2004);

• Thermal analysis determining the water content and ash, loss of mass for con­stituents versus temperature, thermal stability, among other parameters asso­ciated with temperature effects on the material: thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC)—can be applied for pro­cesses, feedstock, and biofuels quality control (Kanaujia et al. 2013);

• Electrochemical the determination of metal oxidation states, quantification of organic and inorganic compounds, polar contaminants in effluents or products: potentiometry, voltammetry, polarography, and amperometry—can be applied for quality control of biofuels (Takeuchi 2007);

• Chromatography (liquid and gas) identification and quantification of organic compounds (volatile, semi-volatile, and nonvolatile) and inorganic, polar, and non­polar, such as sugars from sugarcane or starch, and its products of conversion pro­cesses: high performance liquid chromatography (HPLC) or ultra-high performance liquid chromatography (UPLC) with refractive index, ultraviolet-visible, diode array, fluorescence, mass spectrometry, and light scattering detectors; gas chroma­tography (CG) with flame ionization, thermal conductivity, electron conductivity, and mass spectrometry detectors—can be applied for feedstock, processes monitor­ing, and quality control of biofuels (Mischnick and Momcilovic 2010);

• Spectroscopy and spectrometry identification and quantification of organic and inorganic compounds, polar and nonpolar, such as metals and by-products in bio­fuel synthesis, by means of radiation interaction or radiation production: nuclear magnetic resonance, Fourier transform infrared, X-ray diffractometry and fluo­rescence, ultraviolet and visible spectrophotometry, atomic absorption spectrom­etry (AAS), optical emission spectrometry—can be applied for feedstock, process monitoring, and quality control of biofuels (Shuo and Aita 2013; Orts et al. 2008);

• Mass spectrometry identification and quantification of organic compounds, by means of molecular fragmentation—can be applied for process monitoring, to verify the product purity, and for metabolic engineering approaches of microor­ganisms (Orts et al. 2008; Jang et al. 2012);

• Microscopy (e. g., scanning electron microscopy, transmission electron micros­copy, and atomic force microscopy): observation of surface atomic composition and disposition of biomass components (morphology)—are frequently used for natural polymers and fibers (Hu 2008).

Table 6 presents some general uses of analytical techniques in chemical analysis of biomass for liquid biofuels production.

It is generally desirable to apply the highest possible number of techniques to obtain the greatest amount of information about a biomass. For example: Sugarcane could be analyzed by HPLC-refractive index detector to determine the sugar content, its molecular characteristics could be characterized by near-infra­red spectroscopy, and its energy content by differential scanning calorimetry. This same analytical approach could be applied to an oil crop for biodiesel production: GC-flame ionization detector for content of fat acids and esters in is grains; near­infrared spectroscopy for molecular characteristics, and differential scanning calo­rimetry for energy content.