Speciation analysis of inorganic and organic arsenic in Canadian seafoods by chemical separation and neutron activation Y. Shi 1,2 • A. Chatt 1 Received: 23 August 2018 / Published online: 28 August 2018 Ó Akade ´miai Kiado ´, Budapest, Hungary 2018 Abstract A new method consisting of methanol–methyl isobutyl ketone (MIBK)–water extraction and open-column cation exchange chromatography followed by HPLC was developed for the separation of total, residual, lipid-soluble, and five water soluble arsenic species including AsB, MMA, DMA, As(III), and As(V) in selected Canadian seafood samples. The mass fractions of arsenic were determined by neutron activation analysis with a detection limit of less than 20 lg kg -1 . The method was validated by analyzing reference materials. The MIBK phase contained most of the lipid-soluble arsenic and indicated a linear relationship between the lipid content and lipid-soluble arsenic. Keywords Inorganic and organic arsenic species Á Neutron activation analysis Á Chemical separation Á Seafood Introduction The speciation of arsenic in foodstuffs has become increasingly important because the toxicity of this element depends on its chemical forms, and the total elemental determination is no longer suitable for toxicity assessment [1]. It is well known that seafood contains relatively high levels of arsenic, and past studies mostly concentrated on the identification and determination of water-soluble arsenic species, which of course, accounts for much of the arsenic in marine organisms [2]. A large number of pub- lications including several comprehensive review papers have been published on this subject [2–6]. Characteristics and chemical forms of some arsenic in marine organisms are fairly well understood. They are mostly organic in nature and water-soluble [7, 8]. Since its discovery in the western rock lobster [9], arsenobetaine (AsB) has been found to be the main arsenic compound in a wide range of marine animals, including fish [10, 11], crustaceans [12, 13], mollusks [14, 15], and gastropods [16]. Tetram- ethylarsonium ion (TMA) has been found in the clam Meretrix lusoria [14], the gastropod Tectus pyramis [17], some species of bivalves [18], and possibly in the NRCC Dogfish Muscle reference material DORM-2 [19] at lower levels. Arsenocholine (AsC) has been found as a minor species in some species of shrimp [20, 21], and even trimethylarsine oxide (TMAO) at low concentrations has been identified as a natural component in some types of marine animals [18]. With the improvement of analytical techniques, there has been more and more evidence of the presence of AsC, TMA, TMAO, monomethylarsonate (MMA), dimethylarsonate (DMA) and inorganic arsenic in marine animals [8, 16, 22–25]. Besides the known arsenic species, unidentified arsenic chromatographic peaks are also observed in the analysis of some marine organisms [16, 22–25]. Hanaoka and co-workers reported AsB as the major component together with AsC and TMA as minor components in two kinds of jellyfish [26]. A number of analytical techniques have been applied to the determination of arsenic species in seafood and water. Lately many hyphenated techniques, such as LC-ICP-MS, LC-ICP-OES, LC-ICP-AES, IC-ICP-MS, IC-AFS and HG- F-AAS, have been employed with LC-ICP-MS leading the way [27–35]. The extraction of arsenic compounds from seafood samples is the first yet important step towards its & A. Chatt chatt@dal.ca 1 Department of Chemistry, Trace Analysis Research Centre, Dalhousie University, 6274 Coburg Road, Room 212, PO BOX 15000, Halifax, NS B3H 4R2, Canada 2 Present Address: Isotopic Analysis Section, Analytical Chemistry Branch, Canadian Nuclear Laboratories, Chalk River, ON K0J 1J0, Canada 123 Journal of Radioanalytical and Nuclear Chemistry (2018) 318:785–795 https://doi.org/10.1007/s10967-018-6164-y