School of Pharmaceutical Sciences, Wuhan University, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education, Wuhan, China.
Analyst. 2013 Feb 21;138(4):1226-31. doi: 10.1039/c2an36455g.
Jasmonic acid (JA), a type of plant hormone, is widely distributed in a variety of higher plants at very low concentrations, usually several nanograms per gram (ng g(-1)) fresh weight of the plant tissue. The determination of endogenous JA is challenging work. The typical electrochemical oxidation behavior of JA could only be achieved under extreme conditions such as strongly acidic medium (H(2)SO(4)) and high applied working potential (1.4-1.6 V), which cannot be used in the electrochemical detection for liquid chromatography (LC). To realize electrochemical detection for LC separation, a mild supporting electrolyte for JA oxidation is required, as the supporting electrolyte solution also serves as the mobile phase of LC. Thus, a novel electrochemical derivatization with dopamine (DA) has been developed and successfully applied to the analysis of endogenous JA in wintersweet flowers and rice florets by liquid chromatography coupled with electrochemical detection (HPLC-ECD). Under optimized experimental conditions including a detection potential of +0.90 V, and 0.04 mol L(-1) acetate buffer solution (pH 5.07) : acetonitrile (67 : 33, v/v) as the mobile phase, the contents of JA in wintersweet flowers and rice florets were respectively determined to be 7.86 μg g(-1) and 308 ng g(-1), consulting the linear relationship between the peak area of JA-DA derivatives and the standard JA concentration (1.0 × 10(-7) mol L(-1) to 2.0 × 10(-5) mol L(-1), R = 0.9986) with a detection limit of 5.0 × 10(-8) mol L(-1) (S/N = 3). The results were consistent with those by LC-UV and LC-MS methods in our group, indicating that this novel pre-column electrochemical derivatization method is feasible.
茉莉酸（JA）是一种植物激素，广泛分布于各种高等植物中，浓度非常低，通常为植物组织鲜重的几个纳克每克（ng g(-1)）。内源性 JA 的测定是一项具有挑战性的工作。JA 的典型电化学氧化行为只能在极端条件下实现，例如强酸介质（H(2)SO(4)）和高应用工作电位（1.4-1.6 V），这不能用于 LC 的电化学检测。为了实现 LC 分离的电化学检测，需要一种温和的 JA 氧化支持电解质，因为支持电解质溶液也用作 LC 的流动相。因此，已经开发了一种新的电化学衍生化方法，并用多巴胺（DA）成功地应用于液相色谱电化学检测（HPLC-ECD）分析冬季梅花和水稻小花中的内源性 JA。在包括检测电位为+0.90 V，和 0.04 mol L(-1)乙酸盐缓冲液（pH 5.07）：乙腈（67：33，v/v）作为流动相在内的优化实验条件下，冬季梅花和水稻小花中 JA 的含量分别确定为 7.86 μg g(-1)和 308 ng g(-1)，参考 JA-DA 衍生物峰面积与标准 JA 浓度（1.0 × 10(-7) mol L(-1)至 2.0 × 10(-5) mol L(-1)，R = 0.9986）的线性关系，检测限为 5.0 × 10(-8) mol L(-1)（S/N = 3）。结果与本课题组的 LC-UV 和 LC-MS 方法一致，表明这种新的柱前电化学衍生化方法是可行的。
