First_Aid.jpghand_print.jpgtraffic_cone.jpgMSDS for Povidone-IodineMSDS for Iodine Lugol's SolutionMSDS for Iodine MSDS for Methyl VioletMSDS for Crystal Violet TSMSDS for Ninhydrin SolutionMSDS for Super GlueMSDS for Water

external image FINGERPRINT.jpg


Forensic Chemistry Fingerprinting

Jane Russell and Stacy Tanguay

Organic Chemistry 2009

Collaborating Instructor: Mrs. Ashworth, Memorial High School, Manchester, NH


Introduction:



Ever since the early 1900's, fingerprints have been successfully used to solve crimes. The success has been accredited to fingerprints' ability to identify a suspect at the exclusion of all others. No two fingerprints have ever been found alike. In addition, during the course of one's activities, fingerprints are left on several types of surfaces. Many processing techniques have been developed allowing fingerprints to be enhanced on many of these surfaces. Each technique has the ability to selectively interact, or chemically react, with a component, or several components, found within the fingerprint residue. However, since fingerprint residue can be composed of many different substances (amino acids, water, salts, dust, oil, etc.) and the composition of which is related to each individual's body chemistry and activities, not all techniques work the same on all prints. Also, not all surfaces can be processed for fingerprints. Many rough surfaces tend to be extremely challenging. Furthermore, the quality of the print may be poor or damaged due to the manner in which the print was left and/or due to the subsequent activities (ie - brushing, washing, rain, etc.). Despite these potential disadvantages, fingerprints continue to be highly recognized as extremely valuable evidence. (Introduction from Mrs. Ashworth's Forensic Chemistry Fingerprints lab protocol)


Purpose:


The purpose of our experiments are to complete the fingerprinting procedures while complying with the twelve principles of green chemistry. We have replaced crystal violet with methyl violet in plan A. By this substitution we are able to reduce the use of substances that are toxic to humans and the environment, to use forms of substances that minimize the potential for chemical accidents and utilize chemicals that do not persist in the environment.


Materials:

    • clear sticky tape
    • methyl violet
    • shallow dish
    • distilled water
    • paper
    • black and/or flourescent fingerprint powder
    • fluffy long bristle/feather brush
    • filter paper
    • paper clip
    • string
    • mason jar or jar and tin foil
    • iodine crystals
    • camera

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Materials

Movie Time


Procedures




Plan A: Substitute methyl violet for crystal violet as a green alternative to teachers existing fingerprinting procedure Part G - Sticky - side of Tape Development

  1. Obtain a piece of clear tape large enough for two fingerprints. Make two prints on the sticky side of the tape.
  2. Soak the piece of tape in the methyl violet solution for a few minutes (2-5 min). Remove using tongs and rinse using distilled water.
  3. Examine the contrast. If the prints are faint, soak the tape for a little longer and then rinse again.
  4. Allow the tape to dry and tape or staple the developed prints onto your worksheet.
  5. If prints are not legible, repeat part G just one more time.

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Methyl Violet


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Methyl Violet Print

Plan B: Substitute povidone-iodine solution 10% for silver nitrate solution in existing procedure F.
Procedure:


  1. Prepare two prints as in Part A on one piece of paper using a different finger. Note: A sweaty print is better than an oil print for this part.
  2. Dip the paper into a tray containing povidone-iodine solution using tongs. Remove the paper and let any excess drip from the paper into a waste container.
  3. Set the paper near the window or an Prepare two prints as in Part A on one piece of paper using a different finger for each print. Note: a sweaty print is better than an oil print for this partultraviolet light source and allow it to develop (15-20) minutes. Cut and tape your prints on the worksheet. If the prints are not legible, repeat part F one more time.

Substitution of povidone-iodine solution 10% for silver nitrate solution was unsuccessful.

Plan C: Demonstrate a latent fingerprinting experiment.


  1. Make a fingerprint on a small piece of filter paper by firmly pressing down.
  2. Take a paper clip with a piece of string attached to it and clip this on to the filter paper. Place a few iodine crystals on the bottom of a screw top jar.
  3. Hang the paper clip and the filter paper insider the jar and put the lid on tightly trapping the string outside of the jar and suspending the paper clip and filter paper.
  4. After about ten minutes, the iodine will develop the print on the filter paper and the image should be clear enough to photograph. The print will fade with time and must be photographed if to be kept.



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Iodine Crystal Set Up

Iodine crystals developing a fingerprint on filter paper


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Iodine Print
Quick take a picture, because it will not last forever.




Plan D: Just for a fun an alternative a latent fingerprinting
process that does not require developing.

  1. Place a fingerprint firmly onto a solid surface.
  2. Place brush gently into fingerprinting powder (black or flourescent).
  3. Brush powdered brush over fingerprinted surface.
  4. Remove fingerprint by placing clear sticky tape over exposed fingerprint.
  5. Gently remove the tape without distorting the fingerprint.
  6. Place adhesive tape on paper for examination.









crime_tape.jpgcrime_tape.jpg
Manchester Memorial High School Chemistry Mrs. Ashworth
Forensic Chemistry
Fingerprints


Introduction:

Ever since the early 1900’s, fingerprints have been successfully used to solve crimes. The success has been accredited to fingerprints’ ability to identify a suspect at the exclusion of all others. No two fingerprints have ever been found alike. In addition, during the course of one’s activities, fingerprints are left on several types of surfaces. Many processing techniques have been developed allowing fingerprints to be enhanced on many of these surfaces. Each technique has the ability to selectively interact, or chemically react, with a component, or several components, found within the fingerprint residue. However, since fingerprint residue can be composed of many different substances (amino acids, water, salts, dust, oil, etc.), and the composition of which is related to each individual’s body chemistry and activities, not all techniques work the same on all prints. Also, not all surfaces can be processed for fingerprints. Many rough surfaces tend to be extremely challenging. Furthermore, the quality of the print may be poor or damaged due to the manner in which the print was left and/or due to the subsequent activities (e.g., brushing, washing, rain, etc.). Despite these potential disadvantages, fingerprints continue to be highly recognized as extremely valuable evidence.

Purpose:

The student will be introduced to various fingerprint development techniques used on both porous (ie., paper) and nonporous (i.e., glass) surfaces. The student will recognize many advantages and disadvantages of each technique. It should also become apparent to the student that not all techniques work the same on all prints.

Materials:

Obtain the following material:
1. 250-mL beaker
2. One watch glass
3. One weigh boat

The following materials and chemicals will be supplied as needed:

1. Ultraviolet light source
2. Flash light
3. Fingerprint brushes
4. Black and fluorescent fingerprint powder
5. Lifting tape
6. Iodine crystals, 600-mL beaker, and a hot plate
7. Ninhydrin solution, small tray, tongs, and an iron
8. Superglue
9. Oven
10. Silver nitrate solution and a small tray
11. Crystal violet solution and a small tray


Procedures:

Part A – Fingerprints and Light Sources

1. Prepare two fingerprints, approximately two inches apart, of the same finger on both a piece of paper
and a watch glass (a total of four prints). Good prints can be prepared by first rubbing your fingers on
your forehead or some other oily or sweaty part of the body. Next, gently press the finger onto the
surface. Do not press too hard or the ridges will smash together and a poor fingerprint will result.


2. Using oblique lighting, attempt to find the prints made on each surface. Shining a light source at an
angle to the surface or rotating the surface in a fixed light source can obtain oblique lighting. Record
your results.

3. Using an ultraviolet light source n the darkroom, attempt to find your prints on each surface. Some
fingerprint residue may have inherent fluorescence. Others may fluoresce due to residue acquired
(e.g., cosmetic products). Record your results.

Part B – Fingerprint Powder

1. Obtain a little black and fluorescent fingerprint powder and two fingerprint brushes (one for each
powder used). Develop one print on each surface from part A using black powder, and one on each
surface using fluorescent powder.*

* Only use fluorescent powder brushes when fluorescent powder. You may wish to do this over a
sink and allow extra powder to slowly fall down the paper or watch glass adhering to your prints.
Do not brush too hard or you may damage the prints. Many brushes may already have enough
powder sufficient for enhancement and will not require dipping into the powder.

2. View both fingerprints under normal and ultraviolet light. Record your results. If pattern type cannot
be determined from the prints (i.e., arch, loop, or whorl), repeat part A just one more time. Using the
internet research fingerprint pattern types to become more familiar.

3. Lift the black print from the watch glass using clear tape by carefully placing a piece of tape over the
print, gently rubbing, and then removing. Place the “lift” on your worksheet. Attempt to re-dust the
print and lift again. Place the second “lift” on your worksheet. Wash your watch glass with soap and
water removing all fingerprints.

Part C – Iodine Fuming

1. Prepare two prints as in part A on a piece of paper using a different finger.

2. Make sure the piece of paper is large enough to fit over the mouth of the beaker on the hot plate found
in the fume hood. While wearing gloves, obtain 2-3 iodine crystals using a spatula and place them
into the hot beaker. Immediately place the paper containing the prints over the mouth of the beaker
with the prints down and allow the iodine fumes to fumigate the paper. Watch the prints develop
through the side of the beaker. Record your results.

3. Place a piece of tape over the top and bottom of the paper where one of the prints is found and add a
few drops of starch solution over the second.* Allow the paper to dry and then tape it on your
worksheet. If the print type is not legible, repeat part C just one more time.

* Iodine-fumed prints fade over time. Placing a piece of tape over the top and bottom of the print will
decrease fading. Alternatively, the prints may be fixed with starch solution.

Part D – Ninhydrin Development

1. Prepare two prints as in part A on a piece of paper using again a different finger. Note: A sweaty
print may be better than an oily print for this part.

2. While wearing gloves, dip the piece of paper into the Ninhydrin solution very briefly. The Ninhydrin
solution is flammable. Do not expose to flame or high heat. The solution will also temporarily
change your skin color in the locations in which it comes in contact. Caution must be taken.

3. Using tongs, fan dry the paper. Steam the paper with an iron for a few minutes without having the
iron touch the surface of the paper.

4. If prints have not developed, turn off the steam and hold the iron on the surface of the paper for a few
seconds until the prints begin to develop. Record your observations.

5. Cut out your prints and tape them on your worksheet. If the print is not legible, repeat part D just one
more time.

Part E – Superglue Development

1. Obtain a 250-mL beaker, a watch glass, a weigh boat, and some superglue. Place 5-10 mL of water in
the bottom of the beaker. Each partner makes one fingerprint, of yet another finger, somewhat
side-by-side and close to the center of the watch glass. Each partnership will use one beaker. You
may need to mark whose print is whose. Using oblique lighting, make sure that you can see each
fingerprint and that they are of a good quality.

2. Place the weigh boat in the beaker containing water. Add a few drops of superglue into the weigh
boat and immediately place your watch glass containing the prints over the top of the beaker. Place
the beaker in the oven for 10-20 minutes.*

* Check on your prints periodically. It is possible to over-fume your prints and have too much
superglue adhere to the prints and watch glass, destroying detail.

3. Remove the beaker. Be careful – it is hot. Allow the beaker to cool. Remove the watch glass and
examine your prints under oblique lighting. Record the appearance of the super glued prints.

4. Dust the super glued fingerprints using black fingerprint powder and “lift” them using tape. Attempt
to re-dust the prints and “lift” again. Place both “lifts” on your worksheet. Wash your watch glass
with soap and water removing all fingerprints. You may need to use acetone to remove the superglue.


Part F – Silver Nitrate Development

1. Prepare two prints as in Part A on one piece of paper using a different finger. Note: A sweaty print is
better than an oil print for this part.

2. Dip the paper into a tray containing silver nitrate solution using tongs. Remove the paper and let any
excess drip from the paper into a waste container.

3. Set the paper near the window or an ultraviolet light source and allow it to develop (15-20 minutes).
Cut and tape your prints on the worksheet. If the prints are not legible, repeat part F one more time.

Part G – Sticky-side of Tape Development

1. Obtain a piece of clear tape large enough for two fingerprints. Make two prints on the sticky side of
the tape.

2. Soak the piece of tape in the crystal violet solution for a few minutes. Remove using tongs and rinse
using distilled water.

3. Examine the contrast. If the prints are faint, soak the tape for a little longer and then rinse again.

4. Allow the tape to dry and tape or staple the developed prints onto your worksheet. If prints are not
legible, repeat part G just one more time.

Part H – Unknown Prints

1. Using the development technique of your choice, develop the unknown prints found on the piece of
paper supplied by the instructor.

2. Place the developed unknown prints on your worksheet.

Part I – Rolling Prints (Optional)

1. Allow the instructor to prepare the inking station.

2. Practice rolling your partners fingerprints onto a 10-print card. Roll all 10 fingers. Roll prints into
the center of the body. Remember to hold both ends of the finger. Turn in 10-print card of your
partner with your worksheet.

3. Clean up when finished.

Extension Questions:

1. Explain why or why not part A may serve as a good initial technique.

2. Why do the iodine crystals need to be heated in part C?

3. According to your results in part E, did the superglue-fuming do much enhancing of the fingerprint?
Why did we superglue fume?

4. Did each technique work the same for you and your partner? Explain.

5. Discuss why you chose the development technique employed to develop the unknowns. Make
comparisons to other techniques, discussing advantages and disadvantages. If your first choice did
not work, explain your results and what you did next.





Sources:

Ashworth, Mrs., Forensic Chemistry Fingerprinting, Memorial High School, Manchester, NH, 2009

Doxsee/Hutchinson, Green Organic Chemistry: Strategies, Tools, and Laboratory Experiments, Appendix A

http://education.vetmed.vt.edu/curriculum/vm8054/labs/Lab14/IMAGES/FINGERPRINT.jpg

http://www.topspysecrets.com/fingerprint-powder.html

http://library.thinkquest.org/04oct/00206/p_fin.htm


PPE1.jpgMSDS Sheets
http://www.sciencelab.com/xMSDS-Iodine-9927547
http://www.sciencelab.com/xMSDS-Methyl_violet_2B_-9926113