Application of mid-infrared chemical imaging and multivariate chemometrics analyses to characterise a population of microalgae cells.

A suite of multivariate chemometrics methods was applied to a mid-infrared imaging dataset of a eustigmatophyte, marine Nannochloropsis sp. microalgae strain. This includes the improved leader-follower cluster analysis (iLFCA) to interrogate spectra in an unsupervised fashion, a resonant Mie optical scatter correction algorithm (RMieS-EMSC) that improves data linearity, the band-target entropy minimization (BTEM) self-modeling curve resolution for recovering component spectra, and a multi-linear regression (MLR) for estimating relative concentrations and plotting chemical maps of component spectra. A novel Alpha-Stable probability calculation for microalgae cellular lipid-to-protein ratio Λi is introduced for estimating population characteristics.

Heterogeneous catalytic transesterification of phosphatidylcholine.

The transesterification of phosphatidylcholine (PC) via homogeneous and heterogeneous catalysis was investigated for the production of fatty acid methyl esters (FAME) i.e. biodiesel. Calcium methoxide and calcium oxide were used as heterogeneous catalysts, and KOH as a homogeneous catalyst for the transesterification of phosphatidylcholine (PC)--a polar phospholipid prevalent in eukaryotic organisms. The initial reaction rate was higher for KOH (24.23 g of FAME/g of catalyst.min) than for calcium methoxide (17.06 g of FAME/g of catalyst.min) and calcium oxide (1.06 g of FAME/g of catalyst.min). PC was then mixed with soybean oil at different proportions (i.e. 10%, 30% and 50%, PC10, PC30 and PC50, respectively) which was then used as the feedstock for transesterification using calcium methoxide. When the mass fraction of PC was increased in the feedstock reaction rate also increased. Phosphorus content of the FAME layer of PC100, PC50, PC30 and PC10 was 0.081, 0.041, 0.035 and 0.028% (w/w), respectively.