Determination of total arsenic and hydrophilic arsenic species in seafood

•Arsenosugars and arsenobetaine are the major arsenic species found in seafood.•Inorganic As only detected in geoduck clam and spirulina of seafood samples tested.•Extractable hydrophilic As species account for more than 50 % of total As content.•Total As in wild-caught and aquacultured Coho Salmon is statistically insignificant.•DMA is a decomposition byproduct of AsSugars under acidic extraction conditions.