Salicylic acid (SA) is an important stress signaling phytohormone and plays an essential role in physiological processes in plants. SA fractionation has been carried out batchwise, which is not compatible with the high analytical demand in agronomical studies and increases susceptibility to analytical errors. In this context, a novel flow-batch sample preparation system for SA fractionation on fresh plant leaves was developed. It was based on microwave-assisted extraction with water and conversion of the conjugated species to free SA by alkaline hydrolysis. Free and total SA were quantified by fluorimetry after separation by sequential injection chromatography in a C18 monolithic column. The proposed procedure is directly applicable to plant leaves containing up 16 mg kg⁻¹ SA, with a limit of detection of 0.1 mg kg⁻¹ of SA, coefficient of variation of 3.0% (n = 10), and sampling rate of 4 samples h⁻¹. The flow-batch sample preparation system was successfully applied to SA fractionation in sugarcane, corn, and soybean leaves without clogging or increasing in backpressure. The proposed approach is simple, less time-consuming, and more environmentally friendly in comparison to batchwise procedures.

中文翻译：

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分流样品制备，用于分馏新鲜叶片中的应力信号植物激素水杨酸。

水杨酸（SA）是一种重要的胁迫​​信号植物激素，在植物的生理过程中起着至关重要的作用。SA分馏已分批进行，这与农艺研究中的高分析要求不兼容，并且增加了对分析误差的敏感性。在这种情况下，开发了一种用于在新鲜植物叶片上进行SA分级分离的新型流动样品制备系统。它基于水的微波辅助萃取，并通过碱水解将共轭物质转化为游离SA。在C18整体柱中通过顺序进样色谱分离后，通过荧光法对游离和总SA进行定量。拟议的程序直接适用于含16 mg kg ^-1的植物叶片SA，检测限为0.1 mg kg ^-1的SA，变异系数为3.0％（n  = 10），采样率为4个样本h ^-1。流动分批样品制备系统已成功应用于甘蔗，玉米和大豆叶片中的SA分馏，而不会阻塞或增加背压。与分批过程相比，该方法简单，耗时少且对环境友好。