Functionalized carbon nanotubes, CNTs(COOH), of excess oxygen containing functional groups were prepared using a modified Hummers method. The method is based on oxidizing pristine carbon nanotubes (P-CNTs) by moderately concentrated sulfuric acid and potassium permanganate at low temperature to avoid possible CNTs fragmentation and to preserve the aspect dimensional ratio. The resulting compatible materials were characterized and confirmed by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and electrochemical method including cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Fabrication of a sensitive sensor was much reliable by directly casting of CNTs(COOH) onto the surface of a glassy carbon electrode, CNTs(COOH)-GCE, rather than the tradition electrochemically reduced deposition method, ER-CNTs(COOH)-GCE, which ultimately misplaces large number of surface oxides. The functionalized surface materials exhibited an exceptional electrochemical activity on norepinephrine (NOR) oxidation in the presence of high concentrations of electrochemical active interference species such as ascorbic acid (AA) and uric acid (UA). The proposed sensor was excellently passed the selectivity test and lowered the detection limit of NOR (DL_{3σ, NOR}) into 0.035 μM (6 ppb). It was also applied successfully for detection of NOR in serum blood sample with tolerable recovery percentages.

使用改良的Hummers方法制备了多余的含氧官能团的官能化碳纳米管CNTs（COOH）。该方法基于在低温下用中等浓度的硫酸和高锰酸钾氧化原始碳纳米管（P-CNT），以避免可能的CNT碎裂并保持长宽比。通过扫描电子显微镜（SEM），能量色散X射线（EDX），傅立叶变换红外光谱（FTIR），X射线光电子能谱（XPS）和包括循环伏安法（CV）的电化学方法对所得相容材料进行了表征和确认和差分脉冲伏安法（DPV）。通过将CNTs（COOH）直接浇铸到玻璃碳电极CNTs（COOH）-GCE的表面上，敏感传感器的制造非常可靠。而不是传统的电化学还原沉积方法，ER-CNTs（COOH）-GCE最终会置换大量的表面氧化物。在存在高浓度的电化学活性干扰物质（例如抗坏血酸（AA）和尿酸（UA））的情况下，功能化的表面材料对去甲肾上腺素（NOR）的氧化表现出优异的电化学活性。所提出的传感器通过了选择性测试，并降低了NOR（DL 在存在高浓度的电化学活性干扰物质（例如抗坏血酸（AA）和尿酸（UA））的情况下，功能化的表面材料对去甲肾上腺素（NOR）的氧化表现出优异的电化学活性。所提出的传感器通过了选择性测试，并降低了NOR（DL 在存在高浓度的电化学活性干扰物质（例如抗坏血酸（AA）和尿酸（UA））的情况下，功能化表面材料对去甲肾上腺素（NOR）的氧化表现出卓越的电化学活性。所提出的传感器通过了选择性测试，并降低了NOR（DL_3σ，NOR）转换为0.035μM（6 ppb）。它也已成功地用于检测血清血样中的NOR，且回收率可耐受。