Determination of total mercury in seafood by ion-selective electrodes based on a thiol functionalized ionic liquid

A mercury(II) ion-selective electrode with an ionic liquid (IL), 1-methyl-2-butylthioimidazolium bis(trifluoromethanesulphonyl)imide ([C 1 C 4 Sim]NTf 2 ) as active material was constructed. Parameters affecting the performance of the electrodes such as the dosages of the IL and carbon nanotubes and the aqueous pH values were investigated. Experimental results indicated that the optimal composition of the electrode filling material was 47.6% [C 1 C 4 Sim]NTf 2 , 47.6% tetrabutylphosphonium bis(trifluoromethanesulphonyl)imide (TBPNTf 2 ) and 4.8% carboxylic multi-walled carbon nanotubes (MWCNTs-COOH). Under the selected conditions, the proposed electrodes showed a good linear response in the concentration range of 10 −10 –10 −5  mol L −1 and had a detection limit of 4.1 × 10 −11  mol L −1 . No great interference from common metal ions was found. The proposed electrodes were applied to determine Hg 2+ in seafood samples; the results were comparable to those of the direct mercury analyzer.