定义Definition
薄层色谱是把硅胶、氧化铝等吸附剂均匀涂铺在玻璃板、铝箔或塑料片上作为固定相，点样后用展开剂（流动相）借毛细作用上行展开，使各组分分离的色谱方法。它快速、简便、廉价，是有机合成实验室监测反应的标准手段。
Thin-layer chromatography spreads an adsorbent such as silica gel or alumina evenly on a glass, aluminium or plastic plate as the stationary phase; after spotting, a solvent (mobile phase) rises by capillary action and separates the components. Fast, simple and cheap, it is the standard way to monitor reactions in synthetic laboratories.
原理与操作Principle and practice
硅胶表面的 Si–OH 为极性吸附位点，极性越大的化合物吸附越强、移动越慢、比移值 R_f 越小。操作：用毛细管在距底边约 1 cm 处点样，放入盛有少量展开剂的密闭展开缸中（液面低于点样线），展开至距顶端约 1 cm 时取出，标记溶剂前沿。显色方法：254 nm 紫外灯下观察（含荧光指示剂 F₂₅₄ 的板上，有紫外吸收的化合物呈暗斑）、碘蒸气、高锰酸钾、茚三酮（氨基酸）、磷钼酸或香草醛-硫酸等染色剂。
Silica's Si–OH groups are polar adsorption sites, so more polar compounds stick harder, move more slowly and have smaller R_f values. Spot the sample about 1 cm from the bottom with a capillary, stand the plate in a closed tank with a little eluent below the spot line, remove it when the front is about 1 cm from the top and mark the solvent front. Visualise under 254 nm UV (UV-absorbing compounds show as dark spots on plates with F₂₅₄ indicator), with iodine vapour, or with stains such as permanganate, ninhydrin (for amino acids), phosphomolybdic acid or vanillin–sulfuric acid.
由来Origin
1938 年苏联的伊斯梅洛夫和施赖伯用氧化铝薄层分离药用植物提取物。1950 年代德国化学家埃贡·斯塔尔对涂板方法和吸附剂进行标准化，并于 1956 年正式命名“薄层色谱”，使其迅速普及。
In 1938 Izmailov and Shraiber in the Soviet Union separated medicinal plant extracts on thin layers of alumina. In the 1950s the German chemist Egon Stahl standardised plate preparation and adsorbents and in 1956 named the technique thin-layer chromatography, after which it spread rapidly.
应用Applications
TLC 用于监测反应进程（原料点消失、产物点出现）、为柱色谱选择洗脱剂（理想 R_f 约 0.2–0.4）、检查化合物纯度、鉴定化合物（与标准品同板对照）、中药材鉴别和兴奋剂初筛。制备型薄层色谱可分离毫克级样品；高效薄层色谱（HPTLC）配合扫描仪可定量。
TLC monitors reactions (starting-material spot disappearing, product spot appearing), chooses eluents for column chromatography (an R_f of about 0.2–0.4 is ideal), checks purity, identifies compounds against standards on the same plate, authenticates herbal medicines and screens for doping. Preparative TLC separates milligram samples, and high-performance TLC with a scanner is quantitative.
反应Reactions
0 ≤ R_f ≤ 1。
0 ≤ R_f ≤ 1.
年表Timeline
- 1938
伊斯梅洛夫和施赖伯首次使用薄层
Izmailov and Shraiber first use thin layers
- 1956
斯塔尔命名并标准化薄层色谱
Stahl names and standardises TLC