植物色素的色谱分析

用纸色谱法分离叶绿素和类胡萝卜素

Qualitative Analysis Intermediate (High School) 60 分钟 ~$8.00

目标

用纸色谱法分离鉴定植物色素，并计算各色素的Rf值。

背景

Paper chromatography separates mixtures based on differential affinity for the stationary phase (paper) and mobile phase (solvent). Plant leaves contain multiple pigments: chlorophyll a (blue-green), chlorophyll b (yellow-green), xanthophylls (yellow), and carotenoids (orange). These pigments have different polarities, causing them to travel different distances up the paper as the solvent front advances.

安全警告

  • Acetone and petroleum ether are highly flammable — no open flames
  • Work in a well-ventilated area or fume hood
  • Avoid inhaling solvent vapors
  • Petroleum ether is a skin irritant

所需PPE

goggles gloves lab_coat

材料

  • Fresh spinach leaves (5–10 leaves)
    Or other dark green leaves
  • Acetone or isopropanol (50 mL)
    Extraction solvent
  • Petroleum ether (30 mL)
    Chromatography solvent
  • Chromatography paper (2 strips)
    Whatman No. 1 or equivalent
  • Sand (1 teaspoon)
    For grinding

设备

Mortar and pestle Beaker (250 mL) with watch glass cover Pencil (not pen) Ruler Capillary tube Scissors

步骤

1

Grind spinach leaves with a pinch of sand and 5 mL acetone in a mortar until a deep green extract forms.

5 分钟 Acetone is flammable
2

Draw a pencil line 2 cm from the bottom of the chromatography paper. Apply the extract using a capillary tube in a small spot. Let dry and reapply 3–4 times to concentrate.

10 分钟
3

Pour petroleum ether into the beaker to a depth of about 1 cm. Suspend the paper strip so the origin line is just above the solvent level.

5 分钟 Work in fume hood
4

Cover the beaker with a watch glass and let the solvent rise by capillary action. Do not disturb until the solvent front is 1–2 cm from the top.

25 分钟
5

Remove the paper, immediately mark the solvent front with pencil. Let dry completely.

5 分钟
6

Identify the colored bands: carotenoids (orange, highest Rf), xanthophylls (yellow), chlorophyll a (blue-green), chlorophyll b (yellow-green, lowest Rf). Calculate Rf values for each band.

10 分钟

预期结果

Four or more colored bands should be visible. Carotenoids (orange) travel farthest (Rf ≈ 0.9–0.95). Xanthophylls (yellow) at Rf ≈ 0.7. Chlorophyll a (blue-green) at Rf ≈ 0.5. Chlorophyll b (yellow-green) at Rf ≈ 0.4.

清理

Allow all solvents to evaporate in the fume hood. Dispose of paper in general waste. Clean mortar and pestle thoroughly.

详情

类别
Qualitative Analysis
难度
Intermediate (High School)
时长
60 分钟
预估费用
$8.00
步骤数
6
材料
5

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Frequently Asked Questions

What is the objective of 植物色素的色谱分析?
用纸色谱法分离鉴定植物色素，并计算各色素的Rf值。
How difficult is 植物色素的色谱分析?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for 植物色素的色谱分析?
Key safety precautions include: Acetone and petroleum ether are highly flammable — no open flames; Work in a well-ventilated area or fume hood; Avoid inhaling solvent vapors.
What materials are needed for 植物色素的色谱分析?
The main materials required are: Fresh spinach leaves, Acetone or isopropanol, Petroleum ether, Chromatography paper, Sand.
What results should I expect from 植物色素的色谱分析?
Four or more colored bands should be visible. Carotenoids (orange) travel farthest (Rf ≈ 0.9–0.95). Xanthophylls (yellow) at Rf ≈ 0.7. Chlorophyll a (blue-green) at Rf ≈ 0.5. Chlorophyll b (yellow-green) at Rf ≈ 0.4.