LAUSR

In this work, a methodology based on on-line solid phase extraction (SPE) chromatography with spectrophotometric diode array detection was optimized and validated for the trace analysis of benzo(a)anthracene dihydrodiol degradation products from microalgae cultures 5,6-dihydrodiol, 8,9-dihydrodiol and 10,11-dihydrodiol. The two on-line methods for the constituents of the culture, an SPE/on-line SPE chromatographic method for liquid medium and a matrix solid phase dispersion (MSPD)/on-line SPE chromatographic method for biomass presented good linearity in the ranges of 0.5-47ngmL-1 and 2-80ngmg-1 of samples, respectively, with correlation coefficients r>0.99. The percent relative standard deviation (RSD%) values were ≤4.9%. For the liquid medium and biomass methods, the global recoveries were between 84% and 90% and between 67% and 78%, and the limit of detection LODs were ≤0.3ngmL-1 and ≤0.8ngmg-1 respectively. The methodology was applied to exposure bioassays, and for the first time the three metabolites were detected and quantified individually by their appearance in the biomass and when they were excreted into the liquid medium. The metabolite formed in the greatest amount was 10,11-dihydrodiol, and the maximum production of all metabolites was at 6h of exposure. This work contributes to the study of the degradation route of BaA, which has not been elucidated for microalgae until now.