# New Method for Simultaneous Arsenic and Selenium Speciation Analysis in Seafood and Onion Samples
## 3 Materials and Methods
### Final Method
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Column**} & \multirow{2}{*}{**Mobile Phase**} & **As** & **As** & **Cr** & **Cr** & **Se-** & **Se-** & **Se** & **Se** & **Sb** & **Sb** \\  & & **Bet** & **(III)** & **DMA** & **MMA** & **(V)** & **(III)** & **(VI)** & **Cystine** & **Met** & **(IV)** & **(VI)** & **(III)** & **(V)** \\ \hline PRPX-100 & HNO\({}_{3}\) + CH\({}_{3}\)OH & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \hline \multirow{4}{*}{PRPX-200} & HNO\({}_{3}\) + CH\({}_{3}\)OH & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \cline{2-11}  & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH & \(\times\) & ✓ & ✓ & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \cline{2-11}  & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH + EDTA & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \hline BIOWAX & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \hline SUPELCO & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH & \(\times\) & ✓ & ✓ & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \hline WATERS & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH & \(\times\) & ✓ & ✓ & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) \\ \hline DIONEX CGSA & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & ✓ & ✓ & \(\times\) & \(\times\) \\ \hline DIONEX CGSA & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & \(\times\) & \(\times\) & \(\times\) & ✓ & ✓ & \(\times\) & \(\times\) \\ \hline DIONEX AG22 + AS22 & NH\({}_{4}\)NO\({}_{3}\)OH & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ \hline \multirow{4}{*}{DIONEX AS22 + CGSA} & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH & alkaline pH & ✓ & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ \cline{2-11}  & NH\({}_{4}\)NO\({}_{3}\) + CH\({}_{3}\)OH acidic pH & \(\times\) & \(\times\) & ✓ & ✓ & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ \cline{2-11}  & (NH\({}_{4}\)NO\({}_{3}\)) alkaline pH & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ \cline{2-11}  & NH\({}_{4}\)NO\({}_{3}\) + NH\({}_{4}\)HCO\({}_{3}\) & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ \cline{2-11}  & NH\({}_{4}\)HCO\({}_{3}\) alkaline pH & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ \cline{2-11}  & (NH\({}_{4}\))CO\({}_{3}\) + NH\({}_{4}\)HCO\({}_{3}\) & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ \cline{2-11}  & NH\({}_{4}\)HCO\({}_{3}\) & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & ✓ & ✓ & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: LC–ICP–MS method characteristic.