Download LAB_Identification of Unknown Substances I_DrugIDLab_Flinn

Identification of Unknown Substances I – Forensics Investigation Kit
(Adapted from Flinn Lab FB#1644/Pub# 10521)
Introduction:
Is the white power on the floor aspirin, flour, cocaine, or sugar? How do authorities distinguish between substances that
might look alike? To the criminalist the answers may be critical to solving a case or getting a conviction.
Concepts:




Standards/controls
Precipitation
Chemical Reactions
Solubility
Background:
Substance identification is very important in many real-life situations. An unconscious victim has ingested some drug-it is
critical to identify the substance as quickly as possible. A child has swallowed some pills from a medicine cabinet-identification could
be a matter of life or death. Someone is seen selling bags of white powder-it must be identified for a criminal conviction to occur. A
person has died from someone tampering with drug bottles at a local pharmacy-what was added to the antacid tablets?
The basis for identification of unknown substances always hinges upon using known standards for comparison. Without
knowing exactly how a known substance reacts to all tests, it would be impossible to make a positive identification of an unknown
substance. As new drugs and substances are created, standards for testing these substances must also be developed. The FBI Crime
Lab, for example, works very closely with pharmaceutical companies to produce tests for all new drugs as they are developed. The
“standards,” which are kept on file, are critical for proper identification of “unknowns.”
In the first part of this laboratory, a set of standards will be established for the simulated drugs Scogaine, Davlate, Bradlin,
Irenin and Markopan. In the second part, once the standards have been established, tests will be run to identify an unknown. Though
this simulation is clearly an oversimplification and cannot actually be used to test for drug unknowns, the principles are the same as
those utilized by a crime laboratory. In the criminal lab, the simple chemical reaction would be replaced by more complex methods of
chemical analysis utilizing expensive and complex equipment as the GC/Mass Spectrophometer.
Materials:
Hand Lens
Scogaine
Davlate
Bradlin
Irenin
Markopan
Unknown drug
Paper towels
Crucible tongs or forceps
Chemical resistant gloves
Chemical resistant Aprons
Plastic graduated test tubes with screw tops or micro-well plates
Distilled Water
Sodium Carbonate (aq), Na2CO3, 0.1M
Iodine solution/Iodine ‘water’, I2
Silver Nitrate (aq), AgCl, 0.1M
Hydrochloric acid (aq), HCl, 0.1 M
Microspatula
Aluminum (Al) cups or foil
Wood toothpicks
Safety Goggles
Safety Precautions:
HCl, AgNO3, and I2 are toxic by ingestions or inhalation and severely corrosive to skin and eyes. Na 2CO3 is also a
skin irritant. I2 and AgNO3 solutions will stain the skin and clothing. Wear chemical splash goggles, chemical resistant
gloves and a chemical resistant apron. Wash hands thoroughly upon completion of laboratory work. Clean all work areas so
the next group does not have to work in a contaminated laboratory environment.
Procedure:
1.
Use a Microspatula and obtain approximately a ½ level spatula of each drug in a separate, labeled Microplate well. CLEAN
the spatula after each sample is taken to avoid any cross contamination.
2.
Using a separate well for each drug, fill each with one of the drugs. CLEAN the spatula in between each drug to avoid any
cross contamination.
3.
GENERAL APPEARANCE: Examine each drug with a hand lens. Describe the General Appearance (color, powder or
crystalline [coarse or fine]) on the Knowns/Unknown Substances Worksheet.
4.
HEAT: Make 6 small Al cups with foil. LABEL the cups and place the ½ level spatula of each ‘drug’ into SEPARATE Al
cups. Use tongs or forceps to place the cups on a hot plate at the highest setting. Observe the substances for a MAXIMUM of
3-4 minutes. Note if any MELT (M) or show NO Reaction (NR). Remove the cups from the hot plate. Record the results for
each Heat test, including the unknown on the Knowns/Unknown Substances Worksheet.
5.
HCl Test: Repeat step #1. Add 2-3 drops of HCl (aq) to each tube. As the acid is added, note any reactions that occur of
Effervescence (E) or No Effervescence (NE) and record the results for the HCl test on the Knowns/Unknown Substances
Worksheet.
6.
THOUGHLY wash the micro – well plates and rinse with distilled water. Unclean wells will cause cross-contamination and
you may get incorrect results. Be careful. Pay attention to details.
7.
SOLUBILITY Test: Repeat step #1. Add between 5-10 drops of distilled H2O to each micro-well. Stir with a clean tooth
pick. Note which substances dissolve in water - soluble (S) and which are slightly soluble (SS) or do not dissolve – insoluble
(I). Record the results of the Solubility tests on the Knowns/Unknown Substances Worksheet.
8.
Na2CO3 Test: To the SAME wells used in step #7 add 5-10 drops of Na2CO3 (aq) to each well. Observe each carefully as the
test solution and note any reactions of Effervescence (E) or No Effervescence (NE) on the Knowns/Unknown Substances
Worksheet.
9.
Iodine Test: Repeat step #1. Add 2-3 drops of I2 solution to each sample. CAUTION: The I2 solution has a yellow-brown
color and will stain clothing and skin. Record any color changes when iodine reactions with each of the 5 knowns and the 1
unknown. Record the results of the Iodine tests on the Knowns/Unknown Substances Worksheet.
10. THOUGHLY wash the micro – well plates and rinse with distilled water.
11. AgNO3 Test: Repeat step #1. Add between 5-10 drops of distilled H2O to each micro-well, stir and let sit for approximately
20-30 seconds. Add 2-3 drops of silver nitrate solutions to each micro-well plate. Note if a precipitate forms (PPT) and the
color of the precipitate (W-White, Y-Yellow, R-Red, B-Blue) or if there is NO Reaction (NR). CAUTION: Silver nitrate
will stain skin and clothing. It may take several washings to remove from either surface.
12. THOUGHLY wash the micro – well plates and rinse with distilled water. Shake any excess water from them and DRY the
well plates for the next class. Dispose of all toothpicks and paper towels and gloves in the waste basket, NOT the recylcling.
13. COMPARE the test results for the unknown substance against the “Standards” for each known drug and then determine
which drug the UNKNOWN most closely resembles. Identify your unknown on the line provided at the bottom of the
Knowns/Unknown Substances Worksheet.
NAME:
Partner:
Squad:
Identification of Unknown Substances I – Flinn Scientific Drug ID Lab
Grade:
KNOWNS/UNKNOWN SUBSTANCES WORKSHEET
SCOGAINE
DAVLATE
BRADLIN
IRENIN
MARKOPAN
General
Appearance
Hydrochloric
Acid (HCl)
Test
Heat Test
Solubility
In Water
(H2O)
Sodium
Carbonate
(Na2CO3)Test
Iodine (I2)
Test
Silver Nitrate
(AgNO3) Test
*Use N/R to denote that NO REACTION has occurred.
If a precipitate forms, note its color.
If there is effervescence-(fizzing), note how active (Very [VE], Moderate [ME], or Slow [SE]
Effervescence)
CONCLUSION-Unknown is:
Rubric:
Gr
A+
B+
C+
D+
# Correct
31-32
25-26
18-19
10-11
(Bonus +2)
Gr
A
B
C
D
# Correct
28-30
22-24
14-17
7-9
Gr
ABCF
# Correct
26-27
20-21
12-13
≤6
UNKNOWN
Letter:_____