Rambutan‐Like Nickel Sulfide Modified With Carbon Nanospheres on Nickel Foam for Syringe Membrane Filter‐Based Extraction of Nitroimidazoles

In the present work, nickel sulfide (Ni₃S₂) was modified on the surface of Ni foams (NiF) by in-situ growth, and the prepared rambutan-like Ni₃S₂/NiF materials were further decorated with carbon nanospheres. Subsequently, the prepared C/Ni₃S₂/NiF was loaded into a syringe filter and used for syringe membrane filter-based solid-phase microextraction (SMF-SPME) of five nitroimidazoles (NDZs), followed by high-performance liquid chromatography-ultraviolet detection. The metal affinity of divalent Ni (II) and the imidazole group could contribute to the selective adsorption to NDZs, and the structural porous support of Ni foams, the in-situ modified Ni₃S₂, and carbon nanospheres facilitated the improvement of SMF-SPME efficiency. The main experimental parameters affecting the extraction efficiency were studied, including sample flow rate, adsorption cycle, salt concentration, pH of sample solution, the type and volume of desorption solvent. The selectivity of the adsorbent membrane C/Ni₃S₂/NiF to NDZs was evaluated, and the interactions existing between the modified materials on Ni foam and NDZs were examined to probe the possible adsorption mechanism. Under the optimal conditions, the proposed method showed good linearity from 0.05 to 200 µg L^-1 and possessed low limits of detection within 0.01-0.05 µg L^-1. The reproducibility and reusability of the C/Ni₃S₂/NiF adsorbent were investigated, and the effective enrichment and determination of NDZs in water, milk, and honey samples were also carried out with recoveries of 79.3%-114.5%. This study provides a new strategy for the enrichment and determination of some NDZs in different samples.