Analyzing and
Identifying White Solids
When a crime has
been committed, it is the responsibility of the police, FBI, ATF, and/or
sheriff to collect evidence in order to solve the crime. The evidence must be
collected and analyzed properly to hold up in a court of law. In this lab, you
must collect data and draw conclusions from that data. A forensics scientist
can use hunches and intuition
in trying to
solve a crime; however, when it comes to going to court, only actual facts
should be presented. An expert witness may make inferences but he or she is
subject to questioning by the defense.
Observation : a statement of fact based on what you see, hear, taste, touch, or smell.
A good investigator takes careful notes of everything at the scene. Sketches
and photographs are important parts of every investigation and are completed
prior to touching or collecting any evidence.
·
Physical
properties of a substance are those characteristics that can be observed, such
as color, odor, density, melting point, boiling point, hardness, conductivity,
or taste.
·
Chemical
properties of a substance are those characteristics that describe how the
substance reacts with other chemicals.
Conclusion : a
statement of fact based on the results of experimental testing. For example, if
you have a white powder and add iodine solution to the powder and it turns
black, you can conclude that the white powder contains starch.
Inference: a judgment
or opinion based on observations and/or conclusions from testing. It is a fact
that some illegal drugs are mixed with flour. If a white powder tests positive
for starch , one could infer that the powder is an illegal drug mixed with
flour. However, this inference would not stand up in court. A good investigator
might infer that the powder was an illegal drug but should order additional
testing to confirm the actual composition of the powder.
Objectives:
·
Make
observations
·
Make
inference
·
Draw
conclusions
·
Solve for an
unknown
·
Identify
common substances which are over-the-counter drugs or compounds often used in
the cutting or making of illegal drugs
The FBI Crime Lab
works very closely with the pharmaceutical companies to produce tests for all
new drugs as they are developed. Tests are developed to identify very small
samples of a drug and files are kept to serve as reference for forensics
investigations to use.
Drug
identification is very important. If you arrive on the scene and find an
unconscious victim who has ingested some drug, you need to identify the substance
as quickly as possible. Some over - t h e –counter drugs may cause poisoning
and/or death especially in children.
Background
Information
In this activity
you will test for common over-the-counter drugs as well as common substances
which are found in illegal drugs.
Aspirin, Acetyl salicylic acid: a small sample or a solution of aspirin can be identified by adding a
solution of ferric nitrate. The solution will turn brownish purple if aspirin
is present. In addition to the acetyl salicylic acid (active ingredient)
aspirin tablets also contains starch, silicon dioxide, and preservatives. A
solution of aspirin should be acidic.
Bufferin™ (buffered aspirin ) : you should get the same results with this sample as you did for regular
aspirin. In addition you may get a fizzing produced when you add HCl. This is
because some aspirins are buffered by a carbonate.
Baking Soda, Sodium Hydrogen Carbonate: a sample or a solution of baking soda can be identified by adding a
solution of HCl acid. When the acid is added the solution will fizz. Baking
soda is used in the making of crack cocaine. A solution of baking soda should
be basic.
Tylenol ™ : acetaminophen,
a pain killer similar to aspirin but will not test positive for salicylic acid.
Flour: a
carbohydrate of high molecular weight composed of numerous glucose units.
Sugar: s u c rose
is common table sugar and is made of a glucose and a fructose unit.
Procedure
1 . Add a small
sample of each white powder in 4 of the wells of each column as labeled
in the Data Table.
2. Add 5 drops of
water to each sample in the first well. Stir each mixture with a clean
toothpick. In the Data Table, write if the white powder is soluble (s), slightly
soluble
(ss) or insoluble (ins) in water.
3. Add 1 drop of
universal indicator to each of the wells containing your sample and
water. In the Data Table, write the color
the solution turns.
4. Add 5 drops of
methanol to each of the six sample in the second well. In the Data
Table, write if the white powder is
soluble (s), sightly soluble (ss) or insoluble (ins) in
methanol.
5. Add 5 drops of
Fe(NO3)3 solution to each of the six samples in the third
well. If a
chemical reactions occurs, you should see
a brownish-purple product produced. In the
Data Table put a “P” in the well where you
see this reaction occur.
6. Add 5 drops of
iodine solution to each of the six samples in the last well. If starch is
present, the solution will turn black.
Write a “B” in the Data Table if the solution turns
black.
7. Obtain an
unknown sample from the evidence box. The sample is one of the six sub-
stances you have just tested. Identify the
sample.
O b s e r v a t i o n s
|
|
White
Powders |
|||||
|
|
Aspirin |
Sugar |
Benzoic Acid |
Flour |
Tylenol |
Sodium chloride |
|
Water + Universal
indicator |
|
|
|
|
|
|
|
methanol |
|
|
|
|
|
|
|
Fe(NO3)3 |
|
|
|
|
|
|
|
Iodine |
|
|
|
|
|
|
Record your observations in the table below.
1. Describe what
happened when you added water to the sample.
a. aspirin +
water ________________________________________________________________
b. sugar+
water
________________________________________________________________
c. Bufferin™ + water ________________________________________________________________
d. flour + water
_______________________________________________________________
e. Tylenol™ + water ________________________________________________________________
f. baking soda +
water ____________________________________________________________
g. Unknown sample
# _________________________________________________________