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Fieldston School, Bronx

Summer 2001


The conceptual theory of chromatography

Mixtures:  1. Black ink.  2.  Extract from spinach.  3.  Food dyes.  4.  Amino acids. Solvents available are: Acetone, ethanol, methanol, petroleum ether and water.

Materials:  Chromatography paper, TLC plates and Pasteur pipettes and silica gel are available. Usual lab equipment is also available.

Safety:  This must be done in a well-ventilated lab preferably under a fume hood.  No open flames must be used during this lab.  Goggles and aprons must be used.

Task:  You are provided with the mixtures as listed above.  You are required to find the best method to separate THREE of the above mixtures choosing paper, thin layer or column chromatography.  You should consider the polarity of the substances in the mixtures and solvents when making your decision.  You are allowed to use mixtures of solvents.  You must submit an experimental plan for approval before starting your experiment.  This must include a list of materials and equipment that your group will need for the experiment.  You will need to carry out several trials to find the best method for each separation.  Each member of your team can work on one of the mixtures and you can then share information.

Evaluation: You will be given unknown substances to identify using one or more of the chromatography techniques that you have investigated.  Each person needs to submit a complete report on this experiment.  The materials and methods section as well as the data section may be the same but the introduction, conclusion and discussion must be individualized.

Science concept standards:

S1b, S5a, S5c, S5e, S5f, S6a, S6b, S7d, S7e, S8a, S8c