Analysis of chloropigments in marine sediments using accelerated solvent extraction (ASE)

Abstract

The application of accelerated solvent extraction (ASE) for the analysis of chloropigments in marine sediment samples was studied. Chloropigments (chlorophyll a, b, c and their derivatives) are a group of natural compounds providing valuable data on the state of the aquatic environment. As these compounds are rather unstable and given the considerable risk that alteration products will form, their analysis is difficult. The new extraction method was optimized by testing both solvents and ASE operating conditions (static time, rinse volume, number of static cycles). The results obtained using an ASE technique were compared with those using an ultrasound-assisted extraction method. The results presented in this article indicate that the application of ASE gives high chloropigment recoveries, comparable with conventional methods, but in less time, without the use of elevated temperature during extraction. The type of solvent used has the greatest influence on the extraction efficiency while the effects of the other parameters tested are important in the case of organic-rich sediments. In addition, the influence of freeze-drying of sediment samples on chloropigments composition and target compound stability in freeze-dried sediments during storage under different conditions was examined. The results indicate that freeze-drying does not affect the composition of pigments in the sediment samples and improves reproducibility of results, although extraction of freeze-dried sediments does require the use of a more polar solvent (95% acetone). Freeze-dried sediment samples could be stored in a freezer (-20°C) for up to 6 months, without the risk of degradation of the target compounds.