Analysis of arsenic species in fish after derivatization by GC-MS

► Analysis by GC-MS was investigated for simultaneous quantification of arsenic species. ► Most effective reagent of tested derivatization methods was ethylthioglycolate. ► Derivatization procedure and GC-MS method were optimized to quantify DMA, MMA, As(III,V). ► The accuracy was established by verifying the reference value of DMA in fish CRM. ► The chosen method was applicable for analysis of arsenic polluted seafood matrix.