Chromatography: Principles, Techniques and Analysis | 色谱法：原理、技术与分析

📚 Chromatography: Principles, Techniques and Analysis | 色谱法：原理、技术与分析

Chromatography is a powerful separation technique used to separate, identify and quantify the components of a mixture. It is an essential topic in Cambridge A-Level Chemistry because it links core ideas such as intermolecular forces, polarity, solubility and analytical measurement.

色谱法是一种强大的分离技术，用于分离、鉴定和定量混合物中的各组分。它是剑桥 A-Level 化学的核心主题之一，因为它将分子间作用力、极性、溶解度和分析测量等核心概念联系在一起。

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1. What is Chromatography? | 什么是色谱法？

Chromatography is a physical method for separating the components of a mixture by distributing them between two phases: a stationary phase and a mobile phase. It can be used for qualitative identification, quantitative analysis and purification.

色谱法是一种物理方法，通过将混合物组分分配在固定相和流动相之间进行分离。它可用于定性鉴定、定量分析和纯化。

The separation depends on the different affinities of components for the stationary phase and the mobile phase. A component that interacts more strongly with the stationary phase moves more slowly through the system.

分离取决于各组分对固定相和流动相的不同亲和力。与固定相相互作用更强的组分在系统中移动得更慢。

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2. Mobile Phase and Stationary Phase | 流动相与固定相

The stationary phase does not move; it may be a solid such as silica or a liquid bonded to a solid support. The mobile phase moves over or through the stationary phase and can be a liquid or a gas.

固定相不移动；它可以是硅胶等固体，也可以是键合在固体载体上的液体。流动相在固定相表面或内部移动，可以是液体或气体。

A component with a greater affinity for the mobile phase dissolves in it more readily and travels further in a given time. The balance between adsorption or partitioning controls the separation.

对流动相亲和力更大的组分更容易溶解在流动相中，并在相同时间内移动得更远。吸附或分配之间的平衡控制着分离过程。

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3. Adsorption and Partition Mechanisms | 吸附与分配机制

Adsorption chromatography depends on the reversible binding of solute molecules to the surface of a solid stationary phase. Solutes with stronger surface attractions are slowed down.

吸附色谱依赖于溶质分子与固体固定相表面的可逆结合。表面吸引力更强的溶质会移动得更慢。

Partition chromatography depends on the solubility of solutes in a liquid stationary phase. Solutes that dissolve more in the stationary phase spend more time in it and move more slowly.

分配色谱依赖于溶质在液体固定相中的溶解度。在固定相中溶解得更多的溶质，会在固定相中停留更长时间，因此移动更慢。

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4. Paper Chromatography | 纸色谱法

In paper chromatography, chromatography paper made of cellulose acts as the stationary phase. A small sample spot is placed on a pencil baseline, and the paper is dipped into a suitable solvent.

在纸色谱中，由纤维素制成的色谱纸作为固定相。将少量样品点放在铅笔画的基线上，把纸浸入合适的溶剂中。

The solvent rises by capillary action, carrying the components up the paper at different rates. The baseline must be above the solvent level, and spots should be small to prevent smearing.

溶剂通过毛细作用上升，以不同速率将各组分沿纸携带。基线必须高于溶剂液面，且点样应尽量小，以防止拖尾。

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5. Thin-Layer Chromatography | 薄层色谱法

Thin-layer chromatography uses a thin layer of silica or alumina coated on a glass, metal or plastic plate. TLC is faster, more sensitive and gives sharper separation than paper chromatography.

薄层色谱使用涂在玻璃、金属或塑料板上的硅胶或氧化铝薄层。TLC 比纸色谱更快、更灵敏、分离更清晰。

The plate can be visualised under ultraviolet light or with locating agents. Colourless substances can be made visible by chemical development or by using fluorescent indicators.

谱板可在紫外光下或用显色剂观察。无色物质可通过化学显色法或使用荧光指示剂进行可视化。

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6. Calculating Rf Values | Rf 值的计算

The retention factor, Rf, is a ratio used to characterise a component in a particular chromatographic system. It has no units and is always between 0 and 1.

保留因子 Rf 是用于表征特定色谱体系中某个组分的比值。它没有单位，始终在 0 和 1 之间。

Rf = distance moved by component ÷ distance moved by solvent front

For example, if a dye spot travels 3.2 cm and the solvent front travels 8.0 cm, then Rf = 0.40. Rf values depend on the solvent, stationary phase and temperature, so these conditions must be stated.

例如，如果染料斑点移动 3.2 cm，溶剂前沿移动 8.0 cm，则 Rf = 0.40。Rf 值取决于溶剂、固定相和温度，因此必须说明这些条件。

Rf values are used to identify compounds by comparison with known standards under the same conditions.

Rf 值用于在相同条件下与已知标准品比较来鉴定化合物。

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7. Column Chromatography | 柱色谱法

Column chromatography is a preparative method used to separate larger amounts of a mixture. A vertical glass column is packed with a powdered solid stationary phase, usually silica or alumina.

柱色谱是一种制备方法，用于分离较大量混合物。垂直玻璃柱中填充粉末状固体固定相，通常为硅胶或氧化铝。

The sample is added to the top of the column and eluted with a solvent or solvent gradient. Components move at different speeds and are collected in separate fractions at the outlet.

将样品加到柱顶，用溶剂或溶剂梯度洗脱。各组分以不同速度移动，并在出口处分别接收级分。

This technique is especially useful for purifying organic products after synthesis.

该技术特别适用于合成后有机产物的纯化。

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8. Gas-Liquid Chromatography | 气液色谱法

Gas-liquid chromatography (GLC) is an instrumental technique in which the mobile phase is an inert carrier gas such as helium or nitrogen. The stationary phase is a high-boiling liquid coated on a solid support inside a coiled column in an oven.

气液色谱（GLC）是一种仪器分析技术，其流动相是惰性载气，如氦气或氮气。固定相是涂在固体载体上的高沸点液体，装于烘箱内的螺旋柱中。

The sample is injected, vaporised and swept through the column. Components separate according to volatility and solubility in the liquid stationary phase, reaching a detector at different times.

样品注入后气化，并被载气吹过色谱柱。各组分根据挥发性和在液体固定相中的溶解度不同而分离，并在不同时间到达检测器。

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9. Retention Time and Quantitative Analysis | 保留时间与定量分析

Retention time, tR, is the time from injection to the appearance of a peak maximum. Under constant conditions, a compound has a characteristic retention time that can be used for identification.

保留时间 tR 是从进样到出现峰最大值的时间。在恒定条件下，化合物具有特征性的保留时间，可用于鉴定。

Peak area or peak height is proportional to the amount present. A calibration curve obtained from standard solutions allows quantitative analysis of an unknown sample.

峰面积或峰高与存在量成正比。由标准溶液得到的校准曲线可用于未知样品的定量分析。

For example, ethanol and propanone in a mixture can be identified by comparing their tR values with known standards.

例如，混合物中的乙醇和丙酮可通过将其 tR 值与已知标准品比较来鉴定。

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10. Choosing a Technique and Applications | 技术选择与应用

Technique	Stationary phase	Mobile phase	Main use
Paper chromatography	Cellulose paper	Liquid solvent	Quick qualitative checks
TLC	Silica or alumina layer	Liquid solvent	Qualitative and routine analysis
Column chromatography	Silica or alumina powder	Liquid solvent	Purification
GLC	Liquid on solid support	Inert carrier gas	Volatile mixtures, quantitative work

The choice of technique depends on sample size, volatility and whether the goal is qualitative or quantitative. Paper and TLC are inexpensive for quick qualitative checks. Column chromatography is used for purification. GLC is used for volatile mixtures and accurate quantitative work.

技术选择取决于样品量、挥发性以及目标是定性还是定量。纸色谱和 TLC 成本低，适合快速定性检查。柱色谱用于纯化。GLC 用于挥发性混合物和准确定量工作。

Chromatography is widely used in pharmaceutical purity testing, forensic toxicology, food additive analysis, environmental monitoring and the separation of amino acids or plant pigments.

色谱法广泛用于药物纯度检验、法医毒理学、食品添加剂分析、环境监测以及氨基酸或植物色素的分离。

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