Sample pooling and incurred samples improve analytical throughput and quality control of lipophilic phycotoxins...

Lipophilic marine biotoxins (LMBs) are one of the main risks associated with the consumption of mussels and oysters. Sanitary and analytical control programs are developed to detect the occurrence of these toxins in seafood before they reach toxic levels. To ensure quick results, methods must be easy and fast to perform. In this work, we demonstrated that incurred samples were a viable alternative to validation and internal quality control studies for the analysis of LMBs in bivalve mollusks. These samples were used to optimize, validate, and monitor a simple and fast ultrasound-assisted extraction (UAE) procedure. An internal quality control material containing okadaic acid (227 ± 46 µg kg^-1) was produced and characterized. This material had its homogeneity and stability verified and was included as a quality control in all batches of analytical routine. Besides, a sample pooling protocol for extracts analysis was developed, based on tests for COVID-19. Up to 10 samples could be analyzed simultaneously, reducing the instrumental time of analysis by up to 80%. The UAE and sample pooling approaches were then applied to more than 450 samples, of which at least 100 were positive for the okadaic acid group of toxins.