Preparation of Nitrogen and FeP Doped Carbon Nanotubes for Selective and Simultaneous Electrochemical Detection of Dihydroxybenzoic Acid Isomers

Nitrogen and iron phosphides (i.e., FeP) doped carbon nanotubes (N/FeP-CNT), featured with multi-element co-doping, multi-active sites, and uniform distribution were prepared and characterized. The synergistic effect of nitrogen doped carbon nanotubes (N-CNT) and FeP improved the electrical conductivity and electrocatalytic properties of the modified electrode , which provided a new analysis platform for simultaneous detection of dihydroxybenzoic acid isomers (DHBA isomers). Low detection limits (i.e., 124, 65, and 221   nmol   L −1 for 2,4-DHBA, 3,4-DHBA, and 2,5-DHBA, respectively) and wide detection range (i.e., 0.5-600, 0.5-560, and 0.5–820   μmol   L −1 for 2,4-DHBA, 3,4-DHBA, and 2,5-DHBA, respectively) were obtained for DHBA isomers. In addition, the electrode exhibited good anti-interference ability and long-term stability for the determination of DHBA isomers.