It is used for the detection of drugs in urine - athletes, isolation pigments and dyes, forensic science testing blood found at crime scene, sugars and amino acids an also be separated.
The sample is applied to the paper in small amounts.
As the solvent rises up the paper it carries the dissolved solutes with it. The more soluble is in the solvent, the further the sulute will travel and be separted from the others.
Some spots may be colourless so they will be located by spraying with ninhydrin or treatment with iodine vapures (location agents). These substances form a new compound with the material on the paper and then produce a coloured compound which can be seen clearly.
The Rf value of a spot = distance moved by solute / distance moved by solvent.
NB values will always be less than 1.0
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