main purpose of this assignment is to undertake chromatographic techniques to
identify components in mixtures. The
scenario that is given is I am appointed as newly technical assistant at large
chemical plant, Chemcalequip. As
part of the induction period and to progress in the role I have to demonstrate
skills in a range of practical procedures and techniques. I have to demonstrate
that I can carry out different chromatographic techniques to separate and
identify components in mixtures. I have to make a report and explain the
techniques, analyse and evaluate your results and suggest improvement.
can be used to separate different colours from it mixtures. Mixtures can be
separated such as ink dyes or colouring agents.
chromatography is a method for separating dissolved substances from each other.
It is used when the substance are coloured, such as inks, food colourings and
plant dyes. It works because some of the coloured substances dissolve in the
solvent used better than others, so they travel up the paper.
pure substance will only make one spot on the paper during paper
Thin layer chromatography:
chromatography is using a thin, uniform layer of silicon dioxide gel or alumina
coated onto a piece of glass or metallic element or rigid plastic. The silicon
dioxide gel (or the aluminium oxide) is the stationary form. The stationary
phase for thin layer chromatography also often contains fluoresces in
Ultraviolet illumination light.
Producing the chromatogram:
line is drawn close to the lowest of the plate and a small drop solution
mixture. An y labelling at the plate to
reveal the authentic position of the drop have to additionally be in pencil. If
any of this was performed in ink, dyes from the ink might also circulate
because the chromatogram developed.
spot of mixture is dry, the plate is stood in a layer of solvent in a
full-covered beaker. It’s critical that the solvent level is below the line with
the spot on it.
for masking the beaker is to make sure that the surroundings inside the beaker
is saturated with solvent vapour. To help this, the beaker is frequently coated
with a few filter out paper soaked in solvent. Saturating the environment
within the beaker with vapour stops the solvent from evaporating because it
rises up the plate.
solvent slowly travels up the plate, the dye is separated into different
coloured spots at different rates.
is allowed to rise until it reach the top part of the paper. This is done in
order for maximum separation of the dye.
value of particular compound is the same. To find out the Rf value of compound
you use the formula
For example, if the a red colour
travelled 1.7 cm from the base line while the solvent had travelled 5.0 cm,
then the Rfvalue for the red dye is:
1) Extracted plant pigments
identify plants pigments we use TLC (thin layer chromatography)
2) Amino acids