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Graduated Tubes Graduated test tubes are an economical and convenient alternative to graduated cylin

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Colorimeter/Spectrophotometer. Principle: ... Difference between colorimeter and spectrophotometer ... The colorimeters are used only in visible regions of the ... – PowerPoint PPT presentation

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Title: Graduated Tubes Graduated test tubes are an economical and convenient alternative to graduated cylin


1
Laboratory OrientationFor First Year Students
2
Objectives
  • Practical biochemistry course is designed to
    teach
  • students the fundamental techniques used in
  • biochemistry.
  • In this course students will be exposed to some
  • biochemical procedures and experiments
    commonly
  • used in biochemistry laboratories and to
    provide a
  • basis for understanding how biochemical data
    is
  • obtained, analyzed and presented.

3
1. Lab Instructions
  • Time for practical session is two hours.
  • The student must read biochemical background of
  • experiment before attending the practical
    session.
  • The biochemical basis of practical session will
    be explained
  • by tutor.
  • Quizzes in biochemical basis of practical will
    be given
  • during lab session.
  • Quizzes cannot be repeated.
  • Quiz questions are designed so that they can be
    answered
  • in 5 minutes.
  • Practical work will be performed by students
    under
  • supervision of staff.
  • Laboratory report will be presented.

4
2-Laboratary regulations
  • Students are required to attend all lab
    sessions.
  • Student must attend the lab session at proper
    group
  • and proper time.
  • The class is divided into groups of
    approximately 2-4
  • students under demonstrators guidance during
    the class.
  • Students are not allowed to change practical
    session
  • without the permission of the course tutor.
  • Change of session is only permitted for
    students who
  • presented official medical excuse.
  • Attendance will be recorded by the
    demonstrators.
  • At the end of each laboratory session, students
    have to
  • wash glass wares that have been used and clean
    their
  • work space.

5
Laboratory rules
  • Do not eat food, drink beverages, or chew gum in
    the
  • laboratory. 
  • 2. Be prepared for your work in the laboratory
  • Read all procedures thoroughly before entering
    the
  • laboratory. 
  • Never fool around in the laboratory. 
  • 3. Always work in a well-ventilated area. 
  • 4. Work areas should be kept clean and tidy at
    all times
  • (keep your bag outside).
  • 5. Be alert and proceed with caution at all times
    in the laboratory.  Notify the tutor immediately
    of any unsafe conditions you observe.

6
3. Safety measures
  • CLOTHING

1. Wear safety goggles any time chemicals, heat,
or glassware are used. 2. Contact lenses may be
not be worn in lab. 3. Dress properly during a
laboratory activity.  - Long hair must
be tied back, - Dangling jewelry, and
loose or baggy clothing must be
secured.  - Shoes must completely cover
the foot.  - A lab coat should be worn
7
3. Safety measures b. Handling glass ware and
equipment
  • Examine glassware before each use.  Never use
    chipped, cracked, or dirty glassware
  • Never handle broken glass with your bare hands. 
    Use a brush and dustpan to clean up broken
    glass.  Place broken glass in the designated
    glass disposal container.
  • 3. Do not immerse hot glassware in cold water. 
    The glassware may shatter.

8
3. Safety measures c. Heating substances
  • During using hot plate, take care that hair,
    clothing, and hands are at a safe distance from
    the hot plate at all times. 
  • Use tongs or heat protective gloves if necessary.
  • Heated glassware should be set aside in a
    designated place to cool, and picked up with
    caution. 
  • Never look into a container that is being heated.
  • Do not place hot apparatus directly on the
    laboratory desk.  Always use an insulated pad. 

9
3. Safety measuresd. Handling chemicals
  • All chemicals in the laboratory are to be
    considered dangerous. Do not taste, or smell any
    chemicals. 
  • Check the label on all chemical bottles twice
    before use. 
  • Never return unused chemicals to their original
    container.
  • Never remove chemicals or other materials from
    the laboratory area
  • Dispose all chemical waste properly. 
  • Labels and equipment instructions must be read
  • carefully before use. 
  • Keep hands away from face, eyes, mouth, and body
    while using chemicals or lab equipment.  Wash
    your hands with soap and water after performing
    all experiments. 

10
  • All pipetting must be performed with the use of a
    mechanical
  • device and oral pipetting is to be avoided.
  • Strong acids, alkalis and other toxic substances
    should always be handled with great care.
  • Student should develop and display good
    techniques and
  • working habits such as proper and efficient
    use of laboratory
  • reagents, equipment and instruments.
  • Students will be held responsible for careless
    handling and
  • breakage of glassware and apparatus.

11
Different labels used in labs
Carcinogenic or dangerous
Dangerous to the environment
Harmful
Corrosive
Oxidizable
Explosive
Inflamable
12
4- General Laboratory supplies
Laboratory ware Most of laboratory ware used in
biochemistry laboratory is made of either
glass or plastic.
13
Test tubes
  • Available in different lengths and widths to
    serve a varying number of needs.
  • Usually used for liquid samples, during chemical
    procedures and experiments.
  • Often, formed of Pyrex to allow heating of
    samples.
  • Types of tubes

Test tubes
Centrifuge tubes
Sample tubes
14
Test tube RacksMade from wood, iron or plastic.
Available in different sizes
15
Beakers
  • A simple container for liquids.
  • Very commonly used in laboratories for boiling
    and preprairing solution.
  • Generally cylindrical in shape, with a flat
    bottom.
  • Available in a wide range of sizes, from 1 mL up
    to several litres

16
Flasks
  • The flask has a wide "body" and narrow neck with
    an opening at the top.
  • They have different sizes
  • Used for
  • - making, collecting and measuring
    solutions
  • - chemical reactions, mixing,
    heating, cooling or dissolving,
  • Several types having different functions
  • The most common types are

Volumetric flasks
Boiling flasks
Erlenmeyer flasks
17
Erlenmeyer Flasks (Conical flasks)
  • Used for simple measuring, storing and mixing of
    liquids.
  • It has a conical base with a cylindrical neck.
  • Usually marked on the side (graduated) to
    indicate the volume of their contents.

18
Boiling Flask- Florence Flask
Round Bottom Boiling Flasks
Flat Bottom Boiling Flasks
  • Used for uniform heating and ease of swirling
  • Has a round body with a single long neck and with
    either a flat or a round bottom.

19
Volumetric Flasks
  • Used to measure a very precise and accurate
    amount of a liquid.
  • Come with a stopper or cap.

20
Measuring cylinders
  • Graduated cylinders are used for accurate
    measurements of different volumes of liquid .

Plastic cylinders
Glass cylinder
21
Funnels
Used to hold filter papers when filtering fluid
or for pouring liquid into narrow neck
containers. They have
different sizes.
22
Reagents Bottles
They are available in different sizes and may be
made of brown color glass.
23
Dispensers
Used to deliver liquids including strong acids,
alkalis and solvents.
24
Thermometers
A thermometer is a device which measures
temperature
25
Pipettes
  • Used to transport a measured volume of liquid.
  • Types
  • 1. Automatic pipettes
  • 2. Glass pipettes

26
1. Automatic pipettes
  • They may be of fixed or variable volume
  • Types
  • -Micropipettes
  • dispense between 1 and 1000 µl
  • -Macropipettes
  • dispense a greater volume of liquid.

27
2. Glass pipettes
2.Graduated pipettes - Straight-walled,
and graduated for different volumes such as 1, 2,
5 10mL.
1. Bulb pipettes - Calibrated for a single
volume. - Typical volumes are 10, 25, and
50 mL.
28
Pipette Pumps and Bulbs  
Bulbs
Pumps
Both Pumps and Bulbs are used to fill glass
pipettes
29
Pasteur pipettes
Used to transfer small quantities of liquids.
Glass Pasteur pipettes -glass tubes tapered to a
narrow point, and fitted with a rubber bulb at
the top.
Plastic pasteur pipettes made of single plastic
piece.
30
Droppers
Graduated droppers
Ungraduated droppers
31
Burette
  • They vary in sizes
  • The outflow of liquid from buret is usually
    controlled by a stopcock.
  • Used to dispense known amounts of a Liquid
    reagent in titration experiments.

32
Wash Bottles formed from Polyethylene
33
General Laboratory Equipments
  • Centrifuges
  • Vortex mixer
  • Water bath and shaker
  • Hot plate and magnetic stirrer
  • Hot oven
  • Balances
  • Coloremeter and Spectrophotometer

34
Centrifuges
Is an instrument that accelerate gravitational
separation of substances that differ
significantly in their masses They are used
to 1-Separate particles from solution in
which they are suspended (e.g. separation of
cells from blood to provide cell-free plasma)
2- Separate two liquid phases of
different densities (e.g. extracting solute from
aqueous to organic solvents)
Figure 8 Centrifuge
35
Vortex mixer for stirring and mixing of liquids
of test tubes and other small vessels
Stir bar It is a magnetic bar, used to stir a
chemical mixtures or solution.
Magnetic stirrer with magnets
36
Water Bathes 
37
Hot plate
Hot ovens
Used for heating heating tasks
38
Electronic Balance
39
Fume hood
A fume hood or fume cupboard used to limit a
person's exposure to hazardous fumes.
40
Colorimeter/Spectrophotometer
  • Principle
  • Many important biological solutions are estimated
    as colored solutions, in which the intensity of
    the color is proportional to the concentration of
    the biological substance.
  • When light passes in a colored solution, it has
    specific wave length therefore, the intensity of
    the color is measured as its optical density or
    absorbance of its wave length.
  • Spectrophotometry measures the absorbance or
    optical activity of the colored solutions, and
    the intensity of colors are read on its scale.
  • The absorbance of an unknown concentration of a
    particular
  • substance is compared with the absorbance of
    a known concentration of a standard which reacts
    in the same way to produce colored solution to
    obtain the exact concentration of the test
    unknown sample

41
  • The following formula is usually used
  • Contraction of sample (A )sample X
    conc. Of .standard

  • (A)standard
  • A sample Absorbance (optical density, reading)
    of sample
  • A standard Absorbance (optical density,
    reading) of standard
  • Concentration .standard contraction of the
    known standard solution
  • The zero point of the Spectrophotometry should be
    first adjusted with a solution known as the
    blank. A water blank (colorless solution) or a
    reagent blank may be used. Sometimes the zero
    point of the colorimeter is adjusted against air
    this depends upon the procedure used.

42
  • Difference between colorimeter and
    spectrophotometer
  • The spectrophotometers are used in the UV and
    visible regions of the spectrum.
  • Historically, spectrophotometers use a
    monochromator to analyze the spectrum, but there
    are also spectrophotometers that use arrays of
    photosensors
  • The colorimeters are used only in visible regions
    of the spectrum.
  • Optical filters are used.

43
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