nitrophenols and imidazole

In this work, open-tubular capillary column coated with zeolite imidazolate framework-8 (ZIF-8) nanocrystals was prepared by a layer-by-layer method. The coating was formed by growing ZIF-8 nanocrystals on either bare fused silica capillary wall or the capillary column premodified with amino groups. The shape and the thickness of the coating formed by using these two methods were almost the same. However, the coverage of the ZIF-8 crystals on the bare fused silica capillary wall was higher than that on the capillary column premodified with amino groups. The ZIF-8 coated capillary column was evaluated for open-tubular capillary electrochromatography. The effect of pH value, buffer concentration, and applied voltage on the separation of phenols was investigated. Good separation of nine phenolic isomers was achieved because of the strong interaction between unsaturated Zn sites and phenols. The column performance for o-nitrophenol was as high as 208 860 plates m(-1) . The run-to-run, day-to-day, and column-to-column reproducibility of retention time and resolution for p-nitrophenol and o-nitrophenol were very good with RSDs of less than 6.5%.

Topics: Capillary Electrochromatography; Imidazoles; Nanoparticles; Nitrophenols; Zeolites

In this paper, three kinds of imidazole derivatives, 2-(4-methylphenyl)-4,5-di(2-furyl) imidazole (MDFI), 2-(4-nitrophenyl)-4,5-di(2-furyl) imidazole (NDFI), and 2-(4-tert-butylphenyl)-4,5-di(2-furyl) imidazole (t-BDFI) were synthesized. In an alkaline medium, the chemiluminescence (CL) reaction of imidazole derivatives with H(2)O(2) has been investigated. It was also found that MDFI/H(2)O(2) and t-BDFI/H(2)O(2) systems gave strong CL. When Co(2+) was added into the two CL systems, the CL intensity was remarkably enhanced. In the optimum conditions, the CL intensity is linearly related to the logarithm of concentration of Co(2+). The linear ranges are 5×10(-9)-2.5×10(-7) mol/L for MDFI/H(2)O(2) system and 5×10(-9)-2.5×10(-7) mol/L for t-BDFI/H(2)O(2) system, and the corresponding detection limits are 1.2×10(-9) mol/L and 1.1×10(-9) mol/L, respectively. The method was applied to the determination of Co(2+) in vitamin B(12) injection. Furthermore, the CL mechanism was also discussed.

Topics: Chemistry; Cobalt; Dose-Response Relationship, Drug; Equipment Design; Hydrogen Peroxide; Imidazoles; Ions; Luminescence; Magnetic Resonance Spectroscopy; Models, Chemical; Nitrophenols; Spectrophotometry; Vitamin B 12

Topics: Acetates; Imidazoles; Nitrophenols; Peptides