In the present paper, the ZIF-67/g-C3N4 composite was synthesized and utilized as a modifier for a glassy carbon electrode for the simultaneous voltammetric determination of uric acid (URA) and acetaminophen (ACE) with cetyltrimethylammonium bromide (CTAB) as a discriminating agent. The composite was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption isotherms. The obtained ZIF-67/g-C3N4 composite exhibits good textural properties (specific surface area: 75 m2·g−1) and is stable in water with a pH range of 3 to 10. The ZIF-67/g-C3N4-modified electrode combined with CTAB as a discriminating agent possesses excellent catalytic electrochemistry towards URA and ACE with well-defined electrochemical responses. The electrochemical kinetics study is also addressed. The linear relation of the oxidation peak current of URA and ACE and the concentration ranging from 0.2 μM to 6.5 μM provide a detection limit of 0.052 μM for URA and 0.053 μM for ACE. The proposed method is well-suited to simultaneously analyze URA and ACE in human urine with comparable results with HPLC.

In the present article, the synthesis of zeolite imidazolate framework-67/reduced graphene oxide (ZIF-67/rGO) and voltammetric determination of Rhodamine B (RhB) are demonstrated. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption isotherms. It was found that the ZIF-67/rGO composite consists of ZIF-67 nano-particles highly dispersed on the rGO matrix and possesses a high specific surface area. Because of the synergistic effect of good conductivity of rGO and high surface area of ZIF-67, the ZIF-67/rGO—modified glassy carbon electrode exhibits good electrochemical behavior toward Rhodamine B (RhB) oxidation. The use of this electrode to quantitate RhB with differential pulse voltammetric method was successful with a broad linear range, from 0.96 to 44.07 μg.L-1 of RhB and a low limit of detection of 1.79 μg.L-1. The procedure was able to be applied to quantitatively determine RhB content in several food samples with an exceptional recovery rate (98-103%). The quantitative results highly agreed with that provided by high-performance liquid chromatography, revealing that this material is promising in in situ monitoring of other illegal additives in food.

Bài báo này trình bày QT quá trình tổng hợp vật liệu khung zeolite imidazolate kim loại ZIF-67/graphen oxit dạng khử (ZIF-67/rGO). Vật liệu này là các hạt nano ZIF-67 phân tán đều trên tấm rGO và có diện tích bề mặt riêng lớn (498 m2·g). Lợi dụng độ dẫn điện lớn của rGO và diện tích bề mặt riêng lớn của ZIF-67, điện cực than thủy biến tính ZIF-67/rGO/GCE có tính chất điện hóa phù hợp quá trình oxi hóa Rhodamin-B (RhB). Phương pháp von-ampe xung vi phân sử dụng điện cực biến tính ZIF-67/rGO/GCE để xác định RhB có khoảng tuyến tính rộng (0,96–44,07 μg·L) và giới hạn phát hiện thấp (1,79 μg·L). Có thể sử dụng phương pháp này để xác định RhB trong các loại thực phẩm khác nhau với kết quả tương đương với phương pháp sắc ký lỏng hiệu năng cao.