High-resolution matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and nuclear magnetic resonance (NMR) spectroscopy are powerful tools to identify unknown psychoactive substances. However, in complex matrices, trace levels of unknown substances usually require additional fractionation and concentration. Specialized liquid chromatography systems are necessary for both techniques. The small flow rate of nano LC, typically paired with MALDI-TOF MS, often results in prolonged fractionation times. Conversely, the larger flow rate of semi-preparative LC, used for NMR analysis, can be time-consuming and labor-intensive when concentrating samples. To address these issues, we developed an integrated automatic system that integrated to regular LC. Automatic spot collector (ASC) and automatic fraction collector (AFC) were present in this study. The ASC utilized in-line matrix mixing, full-contact spotting and real time heating (50 °C), achieving great capacity of 5 μL droplet on MALDI plate, high recovery (76–116%) and rapid evaporation in 2 min. The analytes were concentrated 4–8 times, forming even crystallization, reaching the detection limit at the concentration of 50 μg L for 12 psychoactive substances in urine. The AFC utilizes flexible tubing which flash-tapped the microtube's upper rim (3 mm depth) instead of reaching the bottom. This method prevents sample loss and minimizes the robotic arm's movement, providing a high fractionating speed at 6 s 12 psychoactive compounds were fractionated in a single round analysis (recovery: 81%–114%). Methamphetamine and nitrazepam obtained from drug-laced coffee samples were successful analyzed with photodiode array (PDA) after one AFC round and NMR after five rounds. The ASC device employed real-time heating, in-line matrix mixing, and full-contact spotting to facilitate the samples spotting onto the MALDI target plate, thereby enhancing detection sensitivity in low-concentration and complex samples. The AFC device utilized the novel flash-tapping method to achieve rapid fractionation and high recovery rate. These devices were assembled using commercially available components, making them affordable (400 USD) for most laboratories while still meeting the required performance for advanced commercialized systems.

中文翻译：

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使用自动全接触式不分流点样接口和 flash-tap 分级收集，通过 MALDI-TOF MS 和 NMR 光谱简化常规液相色谱

高分辨率基质辅助激光解吸/电离飞行时间质谱 (MALDI-TOF MS) 和核磁共振 (NMR) 光谱是识别未知精神活性物质的强大工具。然而，在复杂的基质中，痕量的未知物质通常需要额外的分馏和浓缩。这两种技术都需要专门的液相色谱系统。纳流液相色谱的小流速通常与 MALDI-TOF MS 配合使用，通常会导致分馏时间延长。相反，用于 NMR 分析的半制备型 LC 的较大流速在浓缩样品时可能非常耗时且费力。为了解决这些问题，我们开发了一种集成到常规 LC 的集成自动系统。本研究中使用了自动点收集器（ASC）和自动馏分收集器（AFC）。ASC 采用在线基质混合、全接触点样和实时加热 (50 °C)，在 MALDI 板上实现了 5 μL 液滴的大容量、高回收率 (76–116%) 和 2 分钟内快速蒸发。分析物浓缩4~8倍，形成均匀结晶，尿液中12种精神活性物质浓度达到50 μg·L的检出限。AFC 使用柔性管，对微管的上边缘（3 毫米深）进行快速攻丝，而不是到达底部。该方法可防止样品损失并最大程度地减少机械臂的移动，从而提供 6 秒的高分离速度。在单轮分析中分离出 12 种精神活性化合物（回收率：81%–114%）。从添加药物的咖啡样品中获得的甲基苯丙胺和硝西泮在一轮 AFC 后使用光电二极管阵列 (PDA) 成功分析，在五轮后使用 NMR 成功分析。ASC装置采用实时加热、在线基质混合和全接触点样，方便样品点样到MALDI靶板上，从而提高低浓度和复杂样品的检测灵敏度。AFC装置采用新颖的闪蒸攻丝方法，实现快速分馏和高回收率。这些设备使用市售组件组装而成，对于大多数实验室而言价格实惠（400 美元），同时仍满足先进商业化系统所需的性能。