Semi-continuous monitoring of HMWPAH in microalgae cultures by PT-SPE/HPLC/FD-UV: Estimation of the degradation constant

• Published in: Analytical biochemistry 2021-11, Vol.633, p.114415-114415, Article 114415
• Main Authors: García de Llasera, Martha Patricia, Hernández Camarillo, Maribel, García Cicourel, Alan Rodrigo, Covarrubias Herrera, María del Rosario
• Format: Article
• Language: English
• Subjects: Chromatography, High Pressure Liquid; Degradation rate; Dihydrodiol metabolites; Microalgae; Microalgae - chemistry; Microalgae - metabolism; Molecular Weight; PAH analysis; Polycyclic Aromatic Hydrocarbons - analysis; Polycyclic Aromatic Hydrocarbons - metabolism; PT-SPE; Solid Phase Extraction; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet
• ISSN: 0003-2697; 1096-0309
• DOI: 10.1016/j.ab.2021.114415

A degradation study has been performed with Selenastrum capricornutum incubated with benzo[a]anthracene and benzo[a]pyrene at 50, 100 and 266 ng mL−1 in liquid cultures. After incubation, these high molecular weight polycyclic aromatic hydrocarbons (HMW PAH) were extracted from both, the medium and biomass in a single step, and then quantified by a sensitive and validated analytical methodology based on pipette-tip SPE and HPLC with fluorescence and UV detection (PT-SPE/HPLC/FD-UV). The methodology presented good linearity r2 > 0.99, LOD of 0.9 and 0.7 ng mL−1 for BaA and BaP, respectively. A fast and semi-continuous appreciation of the degradation behavior was achieved. The pollutants were monitored at different times (0.5–18 h) in the same culture flask, with sampling volume of 1 mL. Biodegradation percentages close to-90% were observed at 18 h. The degradation curves were fitted to the first order reaction (r2 > 0.95) and the degradation rate constants were similar in all bioassays (0.1 h−1) and independent of concentration and compound. The degradation pathways of HMW PAH by microalgae and their enzyme are poorly known but the hypothesis of the degrading enzyme proportionally activated according to the PAH concentration is supported by this result. The early emergence dihydrodiol-type metabolites were detected. [Display omitted] •PT-SPE used for the first time to extract PAH and metabolites from microbial liquid cultures.•Monitoring of PAH and their metabolites in biomass and medium jointly in the same flask.•Simple and fast method to approaching to the kinetic parameters of the degrading enzyme.