Profiling of Organic Compounds in Bioethanol Samples of Different Nature and the Related Fractions

Forty-one bioethanol real samples and related fractions, together with a biobutanol sample, have been analyzed with gas chromatography coupled to either mass spectrometry (GC-MS) or flame ionization detection (GC-FID). Bioethanol with different water contents, samples originated from several sources of biomass, first- as well as second-generation specimens, distillation fractions, samples stocked in containers made of four different materials, and, finally, a biobutanol sample have been analyzed. The number of the compounds found through GC-MS has been 130, including alcohols, aldehydes, ketones, esters, ethers, nitrogen compounds, organic acids, furane derivates as well as other species (e.g., limonene). Afterward, a quantitative determination of major components of bioethanol has been carried out. The achieved results have revealed that, besides ethanol and, in some cases, water, species such as acetaldehyde, methanol, and higher alcohols, as well as 1,1-diethoxyethane, may be present at concentrations above 500 mg L^-1. While the source of bioethanol (nature of the raw material, ethanol generation, or water content) has a direct impact on its volatile organic compound (VOC) profile, the material of the container where the biofuel has been stored does not play a significant role. Finally, the results have demonstrated that, for a given production process, different distillation fractions contain unequal VOC profiles.