📚 IB WJEC Chemistry: Chromatography Key Points | IB WJEC 化学：色谱考点精讲
Chromatography is a powerful separation technique used extensively in chemistry to analyze complex mixtures. In IB and WJEC Chemistry, understanding the principles, types, and calculations associated with chromatography is essential for both practical assessments and written examinations. This article provides a focused revision on key concepts, from paper and thin-layer chromatography to gas and HPLC, along with expert exam tips.
色谱是一种强大的分离技术，广泛应用于化学分析复杂的混合物。在IB和WJEC化学中，理解色谱的原理、类型和相关计算对于实践评估和笔试都至关重要。本文聚焦修订关键概念，从纸色谱和薄层色谱到气相色谱和高效液相色谱，并提供专家考试技巧。
1. The Principle of Chromatography | 色谱原理
All chromatographic techniques rely on the distribution of components between a stationary phase and a mobile phase. The stationary phase is a solid or a liquid supported on a solid, while the mobile phase is a liquid or a gas that carries the sample. Components with a stronger affinity for the mobile phase move faster, whereas those that interact more strongly with the stationary phase are retained and move slower. This differential partitioning leads to separation.
所有色谱技术都依赖于组分在固定相和流动相之间的分配。固定相是固体或负载在固体上的液体，而流动相是携带样品的液体或气体。与流动相亲和力较强的组分移动较快，而与固定相相互作用较强的组分则被保留并移动较慢。这种差异分配导致分离。
In IB and WJEC, you must be able to identify the stationary and mobile phases for each type of chromatography and explain how separation occurs based on polarity and intermolecular forces. The choice of solvent, temperature, and stationary phase dramatically affects resolution.
在IB和WJEC中，你必须能够识别每种色谱类型的固定相和流动相，并根据极性和分子间作用力解释分离如何发生。溶剂、温度和固定相的选择会显著影响分离度。
2. Paper Chromatography | 纸色谱
Paper chromatography is a simple planar technique where the stationary phase is water adsorbed onto cellulose paper, and the mobile phase is a suitable liquid solvent or mixture of solvents. A small spot of the sample is placed near the bottom of the paper, which is then dipped into the solvent. As the solvent rises by capillary action, it carries the components at different rates, producing a chromatogram of separated spots.
纸色谱是一种简单的平面技术，其固定相是吸附在纤维素纸上的水，流动相是合适的液体溶剂或混合溶剂。将少量样品点在纸的底部附近，然后将纸浸入溶剂中。当溶剂通过毛细作用上升时，以不同速率携带组分，产生分离斑点的色谱图。
Typically used for separating coloured compounds like inks or amino acids. In WJEC practical assessments, paper chromatography of plant pigments is common. IB students may also encounter it in the context of separating transition metal ions or identifying unknown mixtures.
通常用于分离有色化合物，如墨水或氨基酸。在WJEC实践评估中，植物色素的纸色谱是常见的。IB学生也可能在分离过渡金属离子或鉴定未知混合物的背景下遇到它。
3. Thin-Layer Chromatography (TLC) | 薄层色谱
TLC uses a thin layer of adsorbent such as silica gel or alumina coated on a glass, plastic, or aluminium plate as the stationary phase. The mobile phase is a liquid solvent. TLC
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