Simultaneous determination of eight nitrofuran residues in shellfish and fish using ultra-high performance liquid chromatography–tandem mass spectrometry

•A integrated approach for eight nitrofurans in shellfish and fish was estabilished.•The method was validated in several shellfish and fish and FAPAS prawn materials.•The method was applied in 397 shellfish and 140 fish samples.•Nitrofurans with illegal levels were detected in 4.3 % shellfish and 5.0 % fish samples.•Semicarbazide detected in shellfish may originate from non-additive sources.