Download docx - Forensic Experiments

.Name: _____________________________ Year & Section: ________ Score: ________Group no. _____ Date: _____________________ Instructor: _____________________

EXPERIMENT 1 THE COMPOUND MICROSCOPE

I. Objective :To know the parts and the correct technique of using the microscope.

.II. Materials: Compund Microscope

III. Drawing: (Draw and label the parts of the microscope).

IV. Questions:1. Give the functions/uses of the following parts of the microscope:

a) Revolving nosepiece –

b) Coarse adjustment knob –

c) Stage –

d) Iris diaphragm –

e) Mirror –

f) Ocular or eyepiece –

g) High power objective –

h) Low power objective –

i) Fine adjustment knob –

j) Mirror –

2. Describe briefly and in systematic order the manner or method of properly using a microscope.

3. Give some precautionary measures in the use of the microscope.

4. Name the three general parts of the microscope and give examples of each general parts.

Name: _____________________________ Year & Section: ________ Score: ________Group no. _____ Date: _____________________ Instructor: _____________________

EXPERIMENT NO. 2MAGNIFICATION

I. ObjectivesTo manipulate the compound microscope and determine the magnification of the object.

II. MaterialsCompound microscope, old newspaper, ruler

III. ProcedureThe size of the image of an object as seen the microscope is several times bigger than its actual size. This means that the object is magnified under the microscope. The following exercises would enable you to determine how many times an object is magnified under the microscope.1. Cut a small letter e from any newspaper. Measure the actual size of the letter e. Put

the letter e in its natural position on a slide. Put a drop of water and cover with a cover slip. Focus under LPO. Observe the position of the letter e under the micro-scope.

2. Place a ruler along the right side of the stage. Look through the microscope with your left eye, at the same time looking at the ruler with your right eye. Measure the letter e under the microscope. Compute the magnification by dividing the size of the image by the actual size of the object.

3. Turn to high power objective. Can you see the whole letter e?

Draw the letter e as seen with the naked eye under the LPO and HPO.

Actual size LPO HPO

4. The magnifying capacity of the microscope.The magnifying capacities of the ocular and the objectives are often indicated on them. An ocular x10 with an objective x4 will magnify an image 40 times. Compute the magnifying capacity of your microscope when you are using the following ocular and objectives.

Ocular Objective Magnifying capacityx10 x10x10 x100x10 X60

x10 X40IV. Questions

1. What is magnification? What parts of the microscope are responsible for magnifying im-

ages? ______________________________________________________________

______________________________________________________________________

______________________________________________________________________

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2. Two microscopes may have different magnification even both are focused under the

LPO. Why? ____________________________________________________________

______________________________________________________________________

______________________________________________________________________

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3. What kind of objective should be used in studying:

a. Whole section of a specimen. _______________________

b. A portion or a section that is very small. _______________

Name:____________________________ Year & Section: __________ Score: ________Group no. _____ Date: _____________________ Instructor: _____________________

EXPERIMENT 3 BLOOD GROUPING OF FRESH BLOOD

Objective:To study the techniques of grouping fresh blood by direct method.

Materials and reagents:Sterilized p-in, needle or lancetBlood typing SeraGlass slides

Procedure:1. Using a sterilized needle, pin or lancet, prick the ring finger of the subject whose

blood group is to be determined.2. Get a glass slide and place one drop of blood on the left side of the slide and

label “A”, put another drop of blood on the right side and label ”B”.3. Place one drop of Anti sera A on the blood with label “A” and a drop of Anti sera

B on the blood with label”B”. Mix both drop of blood with a stick using the other end for “A” and “B” on the other end.

4. Observe under the microscope.5. The blood group where there is agglutination is the blood type of your subject.

Observation:

1. What is the group of the fresh blood of your subject? Why? _________________

________________________________________________________________2. Draw what has been observed under the microscope.

“A” “B”3. What happened when the respective serum was added to the red blood cells?

________________________________________________________________

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4. What is agglutination? ______________________________________________

________________________________________________________________

5. Why agglutination does take place? __________________________________

________________________________________________________________

Conclusion:


EXPERIMENT 4 SEMEN AND SEMINAL STAIN

V. Objective :To study the physical and chemical methods of identifying semen and seminal stains.

VI. Procedure:5. Physical Examination

a. Fresh semen: Observe your fresh semen and describe as follows:

1. Odor : __________________________________

2. Color : __________________________________

3. Feel : __________________________________

4. Appearance : __________________________________

5. Character when exposed to air for half hour:

_______________________________________________

6. Seminal stain: Get a glass slide then place a drop of semen and make a smear using an applicator stick. Air dry then heat fix using an alcohol lamp. Stain by flooding the glass slide with methylene blue for 1 minute. Then wash with water and let dry. Observe under oil immersion objective

VII. Observation:Draw what you have observed in both cases:

VIII. Question:1. Why is dried smear stained with methylene blue?

________________________________________________________________

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2. Is the microscopic examination a specific test for semen and seminal stain?

Why?

________________________________________________________________

________________________________________________________________

3. If no spermatozoa are observed under the microscope can we conclude that

there is no semen? Explain.

________________________________________________________________

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Fresh Semen Stained Semen


EXPERIMENT 6 TEST FOR HAIR

I. Objective :To distinguish human hair from animal hair.

II. Procedure:1. Preliminary examinationGet human and animal hair from the specimen collected and observe:

Qualities Human AnimalColorTextureAppearanceLengthDiameter/ Width

2. Microscopic ExaminationA. Anatomical parts – On a separate slide place human and animal hair. Add a

drop of water and cover. Illustrate observation and label the three anatomical parts.

Human hair Animal Hair

B. Medulla – Place human and animal hair on separate slide. Add a drop of water and cover with glass slip. Observe and draw your observation.


C. Cuticle (Scale Pattern) - Place human and animal hair on separate slide. Add a drop of water and cover with glass slip. Observe and draw your observation.


III. Observation:

1. Describe the Medulla in each case.

Human _____________________________________________________________

___________________________________________________________________

Animal Hair _________________________________________________________

___________________________________________________________________

2. Describe the scale pattern observed.

Human _____________________________________________________________

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Animal Hair _________________________________________________________

___________________________________________________________________

3. Describe the pigment distribution in each case as observed.

Human _____________________________________________________________

___________________________________________________________________

Animal Hair _________________________________________________________

___________________________________________________________________

IV. Question:1. Differentiate human hair from animal hair based on your findings.

________________________________________________________________

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2. What microscopic examination of hair will determine whether it is human or

animal of origin? Why?

________________________________________________________________

________________________________________________________________


EXPERIMENT 5 SMOKE BOMB

The smoke bomb you would purchase from a fireworks store is made from potassium chlorate, sugar, sodium bicarbonate, and a powdered organic dye. When a commercial smoke bomb is burned, the reaction makes white smoke and the heat evaporates the organic dye.

MaterialsSugarPotassium NitrateSkillet or PanAluminum foil

Procedure1. Pour about 3 parts potassium nitrate to 2 parts sugar into the pan or skillet.

Measurements don’t need to be exact, but you want more KNO3 than sugar. If you use equal amounts of KNO3 and sugar, your smoke bomb will be harder to light and will burn more slowly.

2. Apply low heat to the pan. Stir the mixture with a spoon using long strokes. If you see the grains of sugar starting to melt along the edges where you are stirring. Remove the pan from the heat and reduce the temperature before continuing.

3. Basically you are caramelizing the sugar. The mixture will melt and become a caramel or chocolate color. Continue heating/stirring until the ingredients are liquefied. Remove from heat.

4. Pour the liquid into a piece of foil. You can pour the smoke bomb into any shape, onto the object, or into a mole. The shape and size will affect the burning pattern.

5. Allow the smoke bomb to cool, and then you can peel it off the foil.

Observation:

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Conclusion

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EXPERIMENT 8 INK ANALYSIS USING PAPER CHROMATOGRAPHY

Chromatography techniques are methods used to physically separate mixtures of gases, liquids, or dissolved substances. It is particularly useful in identifying substances composed of several different compo0nents, like illicit drugs, paints samples and ink from writing instrument. Substances of similar composition will show separation in similar manner. Substances can be classified this way but exact identification is not possible without further testing. This is considered only as a presumptive test.

In paper chromatography, the components or solutes of the substance being identified will travel at different speeds past the stationary phase. The components that are held less “tightly” by the stationary phase will travel the fastest along with the solvent or liquid phase. The distance each component travels from the origin is called the solute front and the distance the solvent travels is called the solvent front.

The distance that the pigments travel in across the paper is assigned a numerical value called an R ƒ value or retention factor. The R ƒ value is the distance traveled by a single pigment divided by the distance traveled by the solvent (acetone). The further the pigment travels, the greater the R ƒ value.

R ƒ values can never have a value greater than 1! No solute is able to travel faster, and move farther than the solvent. An R ƒ value for a specific component is unique and can be used to compare to a standard. An Ff value is a ratio between two measurements. The measurements cancel out so the value has no unitsA sample chromatogram:

MaterialsFilter paper 3 different kinds of black penBeaker or plastic cup PencilAcetone RulerMasking tape or scotch tape

Procedure:1. Write the pen number on a piece of masking tape with a permanent marker and place at the top

of the strip of filter paper.2. Draw a line 1 cm across each paper 1 cm from the bottom of the paper with a pencil, Number

each piece of paper 1-3 correspond to your number of pens,3. Place small dot of ink from each pen in question on the pencil line of each paper. Let the dot dry.4. Pour acetone into each beaker to a level of 1 cm using a dropper.5. Lower the paper into the beaker so that the bottom of the paper just touches the solvent. The

ink dot should be above the line of solvent. Bend the top of the paper overt the beaker.6. Watch as the solvent moves up the paper. You should also notice that the ink in question also

begins to move. You can observe the separation of different components as they move along the paper.

7. Stop the movement when the solvent front reaches one or two centimeters from the top of the beaker. Remove the paper from the beaker and immediately mark the solvent front with a pencil mark.

8. Measure the distance travelled by the solvent from the starting pencil line to the solvent front.

Start

Distance traveled by 3rd component

Distance traveled by 2nd component

Distance traveled by 1st component

R ƒ = distance solute traveled (no units) distance solvent traveled

Solvent Front

Sample: 1 2 3

Measure the distance travelled by each component from the starting line to the furthest point each component traveled.

9. Compute for the rf values or retention factor. Fill out the report and tape your chromatogram into your lab. Activity. If you are working in a group, photocopy your chromatogram so they can have a copy.

MARKER # 1 2 3

Color observed in Ink sample

Questions:1. What colors did your group observe in each of the black ink samples?2. Do the colors occur in the same order and in the same location on all the samples? Explain

CHROMATOGRAPHY CHALLENGEWork with your group to identify the pens used for each of the “Mystery Marker”.

1. Test each of the Mystery mark strips using the procedure from above.2. Compare your strips to the strips paste on the board.3. Write the number of the pen that you think matches with each of the mystery marks in the space on your

worksheet.4. Write your answer on the table below.

Pen A matches with #_________ Pen D matches with #_________

Pen B matches with #_________ Pen E matches with #_________

Pen C matches with #_________ Pen F matches with #_________


EXPERIMENT 9 INVISIBLE INK

I. Objective:To know some of the commonly used invisible inks and the different methods of developing them.

II. Materials:Invisible inks: Lemon juice, milk, sugar, sulfuric acid, onions, starch, acetic acid barium chloride, phenolphthaleinDeveloper: Heat, Light, water, ammonia, iodine

III. ProcedureUsing pointed rods as writing instrument, write the name of particular invisible ink you are using on different pieces of paper. Label the paper using pencil correspondingly. Allow the writing to dry.

Methods of Development:a. Developing by heat – Carefully heat the piece of papers containing writings using starch,

lemon juice, milk, sugar onion, and sulfuric acid. Note the colors of the writing produced.

b. Developing by Ammonia – expose the paper containing the phenolphthalein solution writings to ammonia fumes and note the color of writing produced.

c. Developing by Water – dip or soak in water for a minute the piece of paper containing writings using dilute solutions of acetic acid and sulfuric acid. Note the results obtained.

d. Developing by Iodine – expose the paper containing starch solution writing to iodine fumes and note the colors of the writing produced.

IV. Observation:

Fill up the table below from the results obtained from above:

INVISIBLE INKS METHOD OF DEVELOPMENT OBSERVATION

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

V. Conclusion:1. What are the principles involved in the development of invisible inks mentioned above?