Original research articleDetermination of copper(II) ion in food using an ionic liquids-carbon nanotubes-based ion-selective electrode

•An ionic liquid-based copper(II) ion-selective electrode was developed.•The proposed electrode had good selectivity and sensitivity.•The measurement accuracy of the proposed electrode could be comparable to GF-AAS.

In this work, a copper(II) ion-selective electrode with an ionic liquid (IL), 1-(2-aminoethyl)-3-butylimidazolium bis(trifluoromethanesulfonyl)imide ([C4NH2C2im]NTf2), as active material has been developed. Parameters affecting the performance of the electrode, such as the dosage of the ILs, the amount of carbon nanotubes, and aqueous pH values, were investigated. The experimental results indicated that the optimal composition of the electrode filling material was 47.6% [C4NH2C2im]NTf2, 47.6% tetrabutylphosphonium bis(trifluoromethanesulfonyl)imide (TBPNTf2) and 4.8% carboxylic multi-walled carbon nanotubes (MWCNTs-COOH). Under the optimal conditions, the developed electrode exhibited a good linear response over the concentration range of 10−10-10−5 mol L−1 and had a low limit of detection, 7.9 × 10−11 mol L−1. No obvious interference from common metal ions was found. The proposed electrode was applied to determine copper (II) ion in food samples and the results were comparable to graphite furnace atomic absorption spectrometry (GF-AAS).