Thin-layer chromatography · 薄层色谱
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| chromatography/krəʊməˈtɒɡrəfi/ | 色谱 | sè pǔ |
| stationary phase/ˈsteɪʃənəri feɪz/ | 固定相 | gù dìng xiāng |
| mobile phase/ˈməʊbaɪl feɪz/ | 流动相 | liú dòng xiāng |
| baseline/ˈbeɪslaɪn/ | 基线 | jī xiàn |
| solvent front/ˈsɒlvənt frʌnt/ | 溶剂前沿 | róng jì qián yán |
Separating on a plate
- Chromatography 色谱 separates a mixture using two phases — one still, one moving.
- In thin-layer chromatography (TLC) the spots travel up a plate.
- Each substance has its own $R_{\text{f}}$ value.
在一块板上分离
- 色谱(chromatography)用两个相分离一个混合物——一个静止,一个移动。
- 在薄层色谱(thin-layer chromatography, TLC)中,斑点沿一块板向上行进。
- 每种物质有它自己的 $R_{\text{f}}$ 值。
TLC route · TLC 途径
Follow a spot up a plate and use Rf to identify substances. · 跟随一个斑点沿一块板向上,并用 Rf 识别物质。
In thin-layer chromatography, the ratio of distances moved by a spot and the solvent is the ______ value. · 在薄层色谱中,一个斑点和溶剂移动的距离之比是 ______ 值。
Always between 0 and 1. · 总是在 0 和 1 之间。
A more soluble component travels further up a TLC plate. · 一个更可溶的组分沿一块 TLC 板行进更远。
It spends more time in the moving solvent. · 它在移动的溶剂中花更多时间。
The set-up
- the stationary phase 固定相 stays still (e.g. aluminium oxide on a plate).
- the mobile phase 流动相 moves (a solvent travelling up the plate).
- the baseline 基线 is where the spots start; the solvent front 溶剂前沿 is the highest the solvent reaches.
Thin-layer chromatography and the Rf value
装置
- 固定相(stationary phase)保持静止(例如一块板上的氧化铝)。
- 流动相(mobile phase)移动(一种沿板向上行进的溶剂)。
- 基线是斑点开始的地方;溶剂前沿是溶剂到达的最高处。
薄层色谱和 Rf 值
In TLC, the stationary and mobile phases are: · 在 TLC 中,固定相和流动相是:
The plate coating stays still; the solvent (mobile phase) travels up, carrying the spots. · 板涂层保持静止;溶剂(流动相)向上行进,携带斑点。
The $R_{\text{f}}$ value
- It is always between 0 and 1.
- A substance that sticks more to the stationary phase moves less → a smaller $R_{\text{f}}$.
A developed TLC plate under UV light: each spot is a separated component.
$R_{\text{f}}$ 值
- 它总是在 0 和 1 之间。
- 一种更多地黏附固定相的物质移动更少 → 一个更小的 $R_{\text{f}}$。
紫外光下一块展开的 TLC 板:每个斑点是一个分离的组分。
The Rf value is: · Rf 值是:
Rf = spot distance / solvent-front distance; it lies between 0 and 1. · Rf = 斑点距离 / 溶剂前沿距离;它在 0 和 1 之间。
A substance that sticks strongly to the stationary phase has: · 一种强烈黏附固定相的物质有:
Strong adsorption means it travels a shorter distance, giving a smaller Rf. · 强吸附意味着它行进更短的距离,给出更小的 Rf。
Using an Rf value
Worked example. A spot moves 3.0 cm while the solvent front moves 7.5 cm. Rf = 3.0 ÷ 7.5 = 0.40 — compared with knowns to identify the compound.
使用一个 Rf 值
例题。 一个斑点移动 3.0 cm,而溶剂前沿移动 7.5 cm。Rf = 3.0 ÷ 7.5 = 0.40——与已知物比较以识别化合物。
You've got it
- TLC: a stationary phase (plate) and a mobile phase (solvent moving up)
- $R_{\text{f}} = \dfrac{\text{spot distance}}{\text{solvent-front distance}}$, always between 0 and 1
- sticks more to the stationary phase → smaller $R_{\text{f}}$
你掌握了
- TLC:一个固定相(板)和一个流动相(向上移动的溶剂)
- $R_{\text{f}} = \dfrac{\text{spot distance}}{\text{solvent-front distance}}$,总是在 0 和 1 之间
- 更多地黏附固定相 → 更小的 $R_{\text{f}}$