Teacher and technician notes TC3.14
Lesson reference: C3.14 Making medicines
Book links: Page 116
Specification links: C3g
Making medicines
Equipment required per student/group:
Student activity AC3.14.1 Making medicines
Set of laminated cards
Student activity AC3.14.2 Testing medicines
Thin layer chromatograph demonstration (optional)
Thin layer chromatography plate, about 8 cm × 5 cm
Three watch glasses
Two thin capillary tubes
Sample of pure aspirin (2-ethanoylhydroxybenzoic acid) (harmful)
Sample of aspirin contaminated with either salicylic acid (harmful)
or benzoic acid (harmful)
Ethanol (highly flammable, harmful)
3
20 cm chromatography solvent
Chromatography beaker or jam jar
A few crystals of iodine (harmful)
Notes on equipment:
These cards can be found
below. They need to be
prepared in advance of the
lesson.
The chromatography plate
needs to be pre-dried and
able to fit into the
chromatography beaker
beaker.
Label the pure aspirin ‘A’ and
the contaminated aspririn ‘B’.
Industrial denatured alcohol
(IDA) will do.
Chromatography solvent can
be made by combining
 cyclohexane (highly
flammable, harmful)
Small beaker
Access to a fume cupboard
Melting point demonstration (optional)
 ethyl ethanoate (highly
flammable, irritant)
Melting point apparatus
Two melting point tubes
Two spatulas
 ethanoic acid (corrosive)
in the ratio 200:100:1
Fundamental Scientific Processes:
Explain how the application of science and technology depends on economic, social and cultural
factors (L, S, H).
Health and Safety notes:
 Wear eye protection for the demonstrations.
 Work in a well ventilated laboratory.
Starting off
 This is potentially quite a time-consuming part of the specification. Some important aspects of
the drug testing process are dealt with in Homework task (HC3.14.1) Making medicines. Make
sure that suitable feedback is given on this task to ensure that all students are fully prepared for
exam questions which cover this section of the specification
Practical activities have been checked for health and safety advice by CLEAPSS.
All users will need to review the risk assessment information and may need to adapt it to local circumstances.
© Oxford University Press 2010
This document may have been altered from the original.
1
 Students will probably use the ideas they have developed about industrial processes in Module
C1 Carbon chemistry and other recent lessons. They will probably raise issues like energy costs
and raw materials costs.
 Emphasise that the cost of drugs is affected by these factors but there are other factors which
are more significant.
Main ideas
Student activity AC3.14.1 Making medicines
 This card-sorting activity follows on from Presentation (IC3.14.3) Making medicines in exploring
the steps involved in drug development.
 The cards should ideally be laminated in advance of the lesson. They can be stored in
envelopes or self-sealing plastic bags for re-use.
✄
Stage
What happens in this
stage
Why this stage is
expensive
development
the drug is given to a group
of healthy volunteers to test
that it is safe
legal approval takes time,
it may be difficult to
persuade doctors to
prescribe the drug
phase 2 and 3 trials
compounds are identified
which may have a beneficial
effect on a disease
the volunteers need to be
paid and closely
supervised by doctors
approval and marketing
a way of making the
compound from raw
materials is developed
it may take several years
before it is clear whether
the drug is effective
discovery research
the product gets legal
approval and doctors are
informed about the drug
the raw materials may be
costly, rare or difficult to
make into the new
compound
phase 1 trials
the drug is given to patients
suffering from the disease
millions of compounds
may need to be tested,
taking many years
Student activity AC3.14.2 Testing medicines
 Students will have done some paper chromatography before. Point out that thin layer
chromatography is similar to paper chromatography but uses a thin layer of silica painted onto a
plastic plate. The principle is very similar. As solvent rises up the plate, different substances
move at different speeds.
 If you choose to demonstrate the thin layer chromatography, it will take around 35 minutes.
However, about 20 minutes of this is spent waiting for the solvent to rise up the paper. You can
use this time to discuss melting point measurements or ask students to complete one of the
Student activity sheets.
 Explain the principles of melting point measurement to the students.
Practical activities have been checked for health and safety advice by CLEAPSS.
All users will need to review the risk assessment information and may need to adapt it to local circumstances.
© Oxford University Press 2010
This document may have been altered from the original.
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 If a melting point apparatus is available, it could be shown to the students. However, the action
of taking a melting point using it is not very visual and unlikely to be very engaging.
 You may want to show how samples are prepared for the melting point apparatus by placing a
few crystals in a melting point tube.
 If time allows, students could analyse the chlorophyll extracts they obtained in Lesson (C3.13)
Batch or continuous? although this is not required by the specification. Full experimental details
can be found by going to the Science & Plants for Schools website at www.saps.org.uk and
searching for ‘chlorophyll chromatography’.
Thin layer chromatograph demonstration (optional)
1 Handle the TLC plate by the edges only and draw a thin pencil line 1 cm from the bottom of the
plate. This is the baseline.
2 Take a few crystals of each of the aspirin samples and dissolve them in a minimum volume of
ethanol on a watch glass. To do this, try a few drops, then add more ethanol if required.
3 Using capillary tubes, place small spots of your aspirin samples on the baseline. Ensure the
three spots are well spaced out along the baseline but are not too close to the side edges of the
TLC plate. Label them A and B in pencil. To achieve small, concentrated spots, apply a small
quantity of the solution then let them dry before adding a second spot on top of the first. Try not
to let the diameter of the spots exceed 2 mm.
4 Working in a fume cupboard, pour some of the chromatography solvent into the beaker to a
depth of no more than 5 mm.
5 Place the chromatography plate in the beaker, making sure that the solvent level is below the
baseline.
6 Cover the beaker with the spare watch glass Leave the solvent to rise up the TLC plate. This will
take about 15–25 minutes.
7 When the solvent has nearly reached the top of the plate, take the chromatogram out of the
beaker. Place the plate in a fume cupboard and allow the solvent to evaporate.
8 The positions of the spots on the plate can be located by examining them under UV light.
However, this will be difficult to do as part of a demonstration. Instead, place the plate in the
small beaker containing a few crystals of iodine. Cover the beaker with a watch glass. The
spots, which were probably just visible before, should show up clearly as dark brown.
Plenary
 The drag-and-drop will give a brief summary of the main steps. If time allows, there could be
more discussion about the nature of the tests and trials, especially the design of the phase III
trials, leading into the homework.
 The extraction of plant chemicals only needs to be covered at a very descriptive level.
Practical activities have been checked for health and safety advice by CLEAPSS.
All users will need to review the risk assessment information and may need to adapt it to local circumstances.
© Oxford University Press 2010
This document may have been altered from the original.
3
Answers
Student activity AC3.14.1 Making medicines
Stage
What happens in this stage
Why this stage is expensive
discovery research
compounds are identified
which may have a beneficial
effect on a disease
millions of compounds may
need to be tested, taking
many years
development
a way of making the
compound from raw materials
is developed
the raw materials may be
costly, rare or difficult to make
into the new compound
phase 1 trials
the drug is given to a group of
healthy volunteers to test that
it is safe
the volunteers need to be paid
and closely supervised by
doctors
phase 2 and 3 trials
the drug is given to patients
suffering from the disease
it may take several years
before it is clear whether the
drug is effective
approval and marketing
the product gets legal
approval and doctors are
informed about the drug
legal approval takes time, it
may be difficult to persuade
doctors to prescribe the drug
Student activity AC3.14.2 Testing medicines
Investigating
A Sample A is the most pure. It has the melting point which is closest to the data book value
B Sample A is the most pure. It produces only one spot so it contains only one substance
Spreading the word
A Both melting point tests and thin layer chromatography tests are done on samples of drugs
because doing two tests increases the reliability of the tests.
B The boiling point of oil of wintergreen should be measured together with a TLC test.
C i
Sample B was impure aspirin.
ii Sample A does not appear to contain any aspirin.
Practical activities have been checked for health and safety advice by CLEAPSS.
All users will need to review the risk assessment information and may need to adapt it to local circumstances.
© Oxford University Press 2010
This document may have been altered from the original.
4