艺术
美容与健康
工艺
文化与历史
娱乐
环境
食品与饮料
逆向工程
科学
体育
技术
可穿戴设备
Two-Dimensional Paper Chromatography
Paper chromatography, already published here, has a hard limit: two substances that happen to travel at the same speed in your solvent land in the same place, and no amount of care will pull them apart. They are not unresolved because the technique is sloppy — they are unresolved because you asked one question and got one answer.
In 1944 Consden, Gordon and Martin at the Wool Industries Research Association asked a second question of the same sheet. Run the paper as usual, dry it, turn it ninety degrees, and run it again in a DIFFERENT solvent. A pair that matched in the first solvent will almost never match in the second, so the spots that were one become two.
It is the cheapest large increase in resolving power in analytical chemistry, it needs no equipment you do not already have, and it separated the amino acids of a protein hydrolysate well enough to start the work that sequenced insulin.
中级
1 day
说明
1
1
Cut a square, and mark the origin in PENCIL
Cut a square, and mark the origin in PENCIL
Cut a square of chromatography or good filter paper, about 15 by 15 cm. Mark a pencil dot 2 cm in from two adjacent edges. That corner is your origin.
Pencil, never pen: graphite is carbon and does not move in any solvent, while ink is a mixture of dyes that will run up the paper and contaminate the very thing you are trying to read. Handle the sheet by its edges from now on — a fingerprint deposits amino acids and oils that show up as their own spots, which is a genuinely common way to get a confusing result.
此步骤所需材料：
色谱纸4 个所需工具：
直尺2
2
Spot small, spot repeatedly, dry between
Spot small, spot repeatedly, dry between
Touch a loaded capillary briefly to the origin, let it dry completely, and repeat five or six times on the same dot.
The aim is a concentrated spot under 3 mm across. Loading it all at once gives a wide wet blot that spreads before it ever starts to travel, and every spot downstream inherits that width. Repeated small applications with drying between build up the quantity without the diameter — and in a two-dimensional run, where the spot has to survive being developed twice, that discipline pays double.
此步骤所需材料：
食用色素1 瓶所需工具：
玻璃毛细管3
3
Run the first dimension
Run the first dimension
Stand the sheet in a closed jar with a shallow depth of your first solvent — a butanol/acetic acid/water mixture is the classic — with the origin edge down and the origin ABOVE the liquid line. Let the front climb to about 2 cm from the top, then take it out and mark the front in pencil immediately.
The jar must be closed and ideally lined with damp paper, so the atmosphere is saturated with solvent vapour. In an open vessel, solvent evaporates from the paper face as fast as it climbs, the front becomes ragged and every Rf you measure is wrong. Mark the front at once: it vanishes as the sheet dries and cannot be recovered.
此步骤所需材料：
乙酸（冰醋酸）10 毫升
乙醇——实验级，95 %100 毫升所需工具：
玻璃罐直尺4
4
Dry it thoroughly — this is the step people rush
Dry it thoroughly — this is the step people rush
Hang the sheet and let it dry completely, for an hour or more, until it has no smell of the first solvent at all.
Any solvent left in the paper joins the second run and makes a mixed mobile phase you did not design, so your second-dimension Rf values are not reproducible and the whole point of the exercise is lost. Acetic acid is particularly stubborn. If the sheet smells, it is not dry, whatever it looks like.
5
5
Turn ninety degrees and run the second solvent
Turn ninety degrees and run the second solvent
Rotate the sheet a quarter turn so the edge that was at the side is now at the bottom, and develop it in a clearly different solvent — phenol-water, or simply a much more aqueous mixture than the first.
'Different' has to mean different in KIND, not just in strength. A second solvent that separates by the same property as the first only stretches the pattern along a diagonal and separates nothing new. The pair you want attacks a different property: one sorting mainly by polarity, the other by size or by acidity.
此步骤所需材料：
99% 异丙醇100 毫升
小苏打5 克所需工具：
玻璃罐6
6
Develop the invisible spots
Develop the invisible spots
If your sample is not coloured, drop a few iodine crystals into a closed jar with the dry sheet and wait. The violet vapour settles into any organic spot and turns it brown.
Iodine is the most forgiving visualiser there is: it stains almost any organic compound, it needs no spray or heat, and the stain FADES as the iodine evaporates, so the sheet is unharmed and can be stained again. Circle every spot in pencil while the colour is there, because in twenty minutes it will not be. Handle the crystals with gloves and keep the jar closed — iodine vapour is an irritant.
此步骤所需材料：
碘晶体2 克所需工具：
玻璃罐
丁腈手套7
7
The resolving power you just bought
The resolving power you just bought
正在加载 Jupyter 笔记本…
所需工具：
直尺8
8
Record the map, not just the picture
Record the map, not just the picture
Measure each spot's distance from the origin along both edges, divide each by the corresponding solvent front distance, and write the pair of Rf values beside it.
A photograph of a stained sheet is unrepeatable — the stain fades and the paper yellows. A table of Rf pairs is a fingerprint you can compare against a run you do next year, or against someone else's, provided you record the solvents and the temperature with it. That table, not the sheet, is what the next rung in this batch and every published method actually exchange.
所需工具：
直尺材料
7- 4 个占位符
- 1 瓶占位符
- 10 毫升占位符
- 100 毫升占位符
- 100 毫升占位符
- 5 克占位符
- 2 克占位符
相关蓝图
这些蓝图共享知识——技术、材料或原理
CC0 公共领域
此蓝图以 CC0 协议发布。你可以自由复制、修改、分发和使用此作品，无需征得许可。
通过购买蓝图中的产品支持创客，他们将获得 创客佣金 （由供应商设定），或创建此蓝图的新版本并将其作为连接包含在你自己的蓝图中以分享收入。