Pharmaceutical chemistry

1. TITRIMETRIC EQUIPMENT
CIU

2. objectives
• To describe the principle of working of
commonly used instruments in titrimetry
• To outline some of their applications
• To describe some of the advantages and
limitations

3. Titrimetric equipment include;
• Pipette
• Burette
• Beaker
• Graduated cylinder
• Stirring rod
• pH meter
• conical flask (Elenmeyer flask)

4. pipette
• Used as a media dispenser
• Common in several designs for various purposes
with differing level of accuracy and precision
• Many work by creating a partial vacuum above
the liquid holding chamber and selectively
releasing this vacuum to draw up and dispense a
liquid.
• Types include air displacement micropipettes,
positive displacement, volumetric, graduated,
pasteur(teat), transfer(beral) pipettes etc.

5. Volumetric pipettes
• Allow the user to measure volume of solution extremely
precisely (precision of 4 significant figures)
• Have a bulb with a long, narrow portion above with a single
graduation mark as it is calibrated for a single volume
• Typical volumes include; 10ml, 25ml,20ml,50ml
• Commonly used to make laboratory solutions from a base
stock as well as prepare solutions for titration
• Advantages
• Precise with delivering solutions
• Limitations
• When leveling out the solution in the device, the pressure
applied by the finger is hard to adjust

7. burette
• Graduated glass tube with tap at one end for delivering known
volumes of a liquid during titration
• Has a stopcock at its lower end and a tapered capillary tube at the
stopcock’s outlet
• Flow of liquid from the tube to the tip is controlled by stopcock
valve
• To main types of burettes; volumetric and piston or digital burette
• Piston burettes are similar to syringes, but with a precision bore and
a plunger. They are manually operated or may be motorized
Advantage
 Accurate with delivering solutions
Limitation
 Calibrated from top to bottom making it harder for meniscus to be
read

9. beaker
• Cylindrical container with a flat bottom
• Most have a small spout(beak) to aid pouring
• Available in various sizes of three form;
• Low form or Griffin form beaker
• Tall form or Bezelius beaker
• Flat beaker or crystallizer
Advantage
 Flat bottom makes it easy to place on flat surfaces e.g.
bench or hot plate
Disadvantages
 Are not particularly precise

11. Conical flask
• Features a flat bottom, conical body and a cylindrical
neck
• The slanted sides and narrow neck allow the contents
of the flask to be mixed by swirling, without the risk of
spillage, making it suitable for titration by placing
under burette
• The flask’s narrow neck can also support filter funnels
Advantages
 Good for swirling
Limitation
 Not particularly accurate for measurement

13. Graduated cylinder
• Used to measure volume of a liquid
• Has a narrow cylindrical shape
• Each marked line on the graduated cylinder
represents the amount of liquid that has been
measured
Advantages
Good for measuring bulk volumes
Limitation
Its narrow shape is not suitable for use in dilution
Measurements usually less precise

15. Volumetric flask
• Laboratory flask calibrated to contain a precise volume at a
particular temperature
• Usually pear-shaped with a flat bottom and made of glass
or plastic
Advantages
 Because there is only one calibration mark on the neck, it
makes it easier to determine the amount of solution
 Particularly accurate
Limitation
 The narrow neck makes it difficult to pour out the solution
 No room for correction when solution exceeds the
calibration mark

17. Stirring rod
• Piece of laboratory equipment used to mix
chemicals and liquids
• Usually made of solid glass(borosilicate or
polypropylene)
Uses
Mixing liquids
They can also break up an emulsion during an
extraction

19. PH meter
• Instrument that measures the hydrogen-ion activity in water-based solutions, indicating
its acidity or alkalinity expressed as pH
• Measures the difference in electrical potential between a pH electrode and a reference
electrode and so is also referred to as a potentiometric pH meter
• The difference in electrical potential relates to the pH of solution.
• Applications
• Soil measurements in agriculture
• Water quality for municipal water supplies
• Brewing, swimming pools and blood chemistry
Advantages
 Can be calibrated and used whenever needed
 Is portable
 Measures pH at equivalence point
 More simpler to use
Limitations
 Expensive compared to test strips
• Needs regular cleaning