Ivandini T A, Sarada B V, Terashima C, Rao T N, Tryk D A, Ishiguro H, Kubota Y, Fujishima A
Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
J Chromatogr B Analyt Technol Biomed Life Sci. 2003 Jul 5;791(1-2):63-72. doi: 10.1016/s1570-0232(03)00204-6.
Boron-doped diamond thin film (BDD) electrodes have been used to study the oxidation reactions and to detect leucine-enkephalinamide (LEA) and its metabolites, tyrosine (T), tyrosyl-alanine (TA), tyrosyl-alanine-glycine (TAG) and leucine-enkephalin (LE) using cyclic voltammetry (CV), flow-injection analysis (FIA), and gradient liquid chromatography (LC) with amperometric detection. At diamond electrodes, well-defined and highly reproducible cyclic voltammograms were obtained with signal-to-background (S/B) ratios 5-10 times higher than those observed for glassy carbon (GC) electrodes. The analytical peaks of LC for LEA and its metabolites were well resolved. No deactivation of BDD electrodes was found after several experiments with standard as well as plasma samples, indicating high stability of the electrode. Calibration curves were linear over a wide range from 0.06 to 30 microM with regression coefficients of 0.999 for all compounds. The limits of detection obtained based on a signal-to-noise ratio of 3:1 were 3, 2.2, 2.7, 20 and 11 nM for T, TA, TAG, LE and LEA, respectively. These values were at least one order lower than those obtained at GC electrodes, which has given limits of detection of 22.88, 20.64, 89.57, 116.04 and 75.67 for T, TA, TAG, LE and LEA, respectively. Application of this method to real samples was demonstrated and validated using rabbit serum samples. This work shows the promising use of conducting diamond as an amperometric detector in gradient LC, especially for the analysis of enkephalinamide and its metabolites.
硼掺杂金刚石薄膜（BDD）电极已被用于研究氧化反应，并使用循环伏安法（CV）、流动注射分析（FIA）和梯度液相色谱（LC）结合安培检测来检测亮氨酸脑啡肽酰胺（LEA）及其代谢产物酪氨酸（T）、酪氨酰 - 丙氨酸（TA）、酪氨酰 - 丙氨酸 - 甘氨酸（TAG）和亮氨酸脑啡肽（LE）。在金刚石电极上，获得了明确且高度可重复的循环伏安图，其信号与背景（S/B）比是玻碳（GC）电极的5 - 10倍。LEA及其代谢产物的LC分析峰得到了很好的分离。在用标准样品和血浆样品进行多次实验后，未发现BDD电极失活，表明电极具有高稳定性。校准曲线在0.06至30 microM的宽范围内呈线性，所有化合物的回归系数均为0.999。基于3:1的信噪比获得的检测限分别为：T为3 nM、TA为2.2 nM、TAG为2.7 nM、LE为20 nM、LEA为11 nM。这些值至少比在GC电极上获得的值低一个数量级，GC电极对T、TA、TAG、LE和LEA的检测限分别为22.88、20.64、89.57、116.04和75.67 nM。使用兔血清样品证明并验证了该方法在实际样品中的应用。这项工作表明，导电金刚石作为梯度LC中的安培检测器具有广阔的应用前景，特别是用于脑啡肽酰胺及其代谢产物的分析。
