多壁碳纳米管修饰电极用于离子色谱分离电活性氨基酸的安培检测

Amperometric detection of oxidizable amino acids at multiwall carbon nanotube film modified electrodes by ion chromatography

将经羧基化的多壁碳纳米管(MWNTs)修饰在玻碳电极表面,制得碳纳米管修饰电极,并通过循环伏安法研究了某些可氧化的氨基酸在该电极上的电催化行为。该电极对半胱氨酸,色氨酸和酪氨酸有明显的电催化作用,且具有较高的灵敏度和稳定性。在一定的色谱条件下,经过离子色谱分离,这些可氧化的氨基酸的检测限分别为:半胱氨酸7.0×10-7mol L;色氨酸2.0×10-7mol L;酪氨酸3.5×10-7mol L(3倍信噪比)。方法已用于头发中这些氨基酸含量的测定。

A multiwall carbon nanotube (MWNTs) film modified electrode was prepared and used as an amperometric sensor for the simultaneous determination of oxidizable amino acids including cysteine, tryptophane and tyrosine. The electrochemical behaviors of these amino acids at this modified electrode were studied by cyclic voltammetry (CV). The results indicated that the MWNTs chemically modified electrode (CME) exhibited efficient electrocatalytic activity towards the oxidation of these amino acids with relatively high sensitivity and stability. Following separation by ion chromatography (IC) with 2.0×10^(-3) mol/L citric acid buffer solution (pH 6.5) as eluent, cysteine, tryptophane and tyrosine could be determined successfully by the MWNTs chemically modified electrodes. Under the optimal conditions, the detection limits were 7.0×10^(-7) mol/L for cysteine, 2.0×10^(-7) mol/L for tryptophane and 3.5×10^(-7) mol/L for tyrosine at the signal-to-noise ratio of 3, respectively. The method was applied successfully to the determination of these substances in samples of human hair.