Matrix solid-phase dispersion-high-performance liquid chromatography with diode array detection as a sustainable alternative for carotenoids analysis in green and brown macroalgae

In recent years, marine macroalgae, i.e., seaweeds, have moved from being considered as a waste or residue to an added-value raw material rich in bioactive compounds, including carotenoids.

Due to carotenoids' physicochemical properties, extracting them from complex matrices is a challenge. Thus, sample preparation techniques must be effective in breaking down the cell matrix without analyte degradation. Conventional techniques to extract carotenoids and other bioactive compounds from macroalgae include Ultrasound-Assisted Extraction (UAE), Pressurized Liquid Extraction (PLE), or supercritical CO₂ extraction.

However, carotenoids are lipophilic compounds with conjugated structures, making them susceptible to thermal degradation, especially when exposed to high temperatures for extended periods. In this way, the use of matrix solid-phase dispersion (MSPD) is a suitable alternative to these classical procedures, as extraction is performed at ambient temperature and pressure. The MSPD experimental parameters affecting extraction, dispersant, sample/dispersant ratio, and extraction solvent were optimized by experimental design to obtain the highest extraction efficiency. A High-Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD) methodology using a C30 column was developed to successfully separate and identify seven carotenoids.

Finally, the MSPD-HPLC-DAD methodology was validated for green, Codium spp., and brown, Kombu spp. macroalgae from the coast of Galicia (northwest Spain), showing its suitability.