title: NMR techniques for determination of lipid content in microalgal biomass and their use in monitoring the cultivation with biodiesel potential.
abstract: In the present investigation, the application of NMR spectroscopic techniques was extensively used with an objective to explore the biodiesel potential of biomass cultivated on a lab scale using strains of Chlorella vulgaris and Scenedesmus ecornis. The effect of variation in the composition of culturing medium on the neutral and polar lipids productivity, and fatty acid profile of solvent extracts of microalgae biomass was studied. Determination of unsaturated fatty acid composition (C18:N = 1-3, ω3 C20:5, ω3 C22:6), polyunsaturated fatty esters (PUFEs), saturated fatty acids (SFAs), unsaturated fatty acids (UFAs), free fatty acids (FFAs), and iodine value were achieved from a single (1)H NMR spectral analysis. The results were validated by (13)C NMR and GC-MS analyses. It was demonstrated that newly developed methods based on (1)H and (13)C NMR techniques are direct, rapid, and convenient for monitoring the microalgae cultivation process for enhancement of lipid productivity and their quality aspects in the solvent extracts of microalgal biomasses without any sample treatment and prior separation compared to other methods. The fatty acid composition of algae extracts was found to be similar to vegetable and fish oils, mostly rich in C16:0, C18:N (N = 0 to 3), and n-3 omega polyunsaturated fatty acids (PUFAs). The lipid content, particularly neutral lipids, as well as most of the quality parameters were found to be medium specific by both the strains. The newly developed methods based on NMR and ultrasonic procedure developed for efficient extraction of neutral lipids are cost economic and can be an effective aid for rapid screening of algae strains for modulation of lipid productivity with desired biodiesel quality and value-added products including fatty acid profile.
authors.affiliation: National Institute of Metrology, Standardization and Industrial Quality - INMETRO, Avenida Nossa Senhora das Graças 50, Xerém, Duque de Caxias, RJ, Brazil. sarpal.as2@gmail.com.
authors.forename: Amarjit S
authors.initials: AS
authors.lastname: Sarpal
authors.affiliation: National Institute of Technology (INT), Rio de Janeiro, Brazil.
authors.forename: Cláudia M L L
authors.initials: CM
authors.lastname: Teixeira
authors.affiliation: National Institute of Metrology, Standardization and Industrial Quality - INMETRO, Avenida Nossa Senhora das Graças 50, Xerém, Duque de Caxias, RJ, Brazil.
authors.forename: Paulo Roque Martins
authors.initials: PR
authors.lastname: Silva
authors.affiliation: National Institute of Metrology, Standardization and Industrial Quality - INMETRO, Avenida Nossa Senhora das Graças 50, Xerém, Duque de Caxias, RJ, Brazil.
authors.forename: Thays Vieira
authors.initials: TV
authors.lastname: da Costa Monteiro
authors.affiliation: National Institute of Metrology, Standardization and Industrial Quality - INMETRO, Avenida Nossa Senhora das Graças 50, Xerém, Duque de Caxias, RJ, Brazil.
authors.forename: Júlia Itacolomy
authors.initials: JI
authors.lastname: da Silva
authors.affiliation: National Institute of Metrology, Standardization and Industrial Quality - INMETRO, Avenida Nossa Senhora das Graças 50, Xerém, Duque de Caxias, RJ, Brazil.
authors.forename: Valnei Smarcaro
authors.initials: VS
authors.lastname: da Cunha
authors.affiliation: National Institute of Metrology, Standardization and Industrial Quality - INMETRO, Avenida Nossa Senhora das Graças 50, Xerém, Duque de Caxias, RJ, Brazil.
authors.forename: Romeu José
authors.initials: RJ
authors.lastname: Daroda
mesh_terms: D056804:Biofuels; D018533:Biomass; D048408:Chlorella vulgaris / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D008055:Lipids / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D044444:Scenedesmus / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism*; D013010:Sonication / Q000379:methods
chemical_list: D056804:Biofuels; D003470:Culture Media; D008055:Lipids
keywords: 1H and 13C NMR; Biofuel; GC-MS; Lipid; Microalgae