Transcript 9.4 Notes mb changes

9.4 Notes
ID, Collection of Evidence
Objectives
 Describe the laboratory tests normally
used to perform a routine drug
identification analysis
 Understand proper collection and
preservation of drug evidence
Drug Identification
 Either a specimen is a specific drug or it is
not
 Chemists must be prepared to support and
defend the validity of the results in a court of
law

Screening test – reduces possibilities


first test is color test
Confirmation test - pinpointing
Drug Identification cont.
The procedures must be able to confirm that
the likelihood of any other substance
responding in an identical manner to a
certain drug is so minimal that there exists
no other conclusion but reasonable scientific
certainty
Analytical schemes
1. Color tests
2. Microcrystalline tests
3. Chromatography
4. Spectrophotometry
5. Mass Spectrometry
Color Tests
1. Marquis reagent – purple with
heroine and morphine; orange with
amphetamines
2. Dillie-Koppanyi – violet blue with
barbiturates
3. Duquenois-Levine – ABC layers
with layer C purple with marijuana
4. Van Urk – purple/blue with LSD
5. Scott Test – ABC (A with cocaine,
blue to pink in B, and blue again in C
layer)
Microcrystalline Tests
 Chemical reagent
added to drug on slide
 Crystalline precipitate
with unique structures
results
Chromatography
 Uses TLC (Thin Layer
Chromatography) and gas
 Requires the Rf
comparison of known and
questioned drugs
 Accompanies color and
crystal test
Spectrophotometry
 Absorption of light in
the UV and IR regions of
the spectrum
 Establishes probable
drug
 IR can specifically ID a
substance
Mass Spectrometry
 GC/MS
 Utilizes the
fragmentation pattern of
sample molecules which
serves as a fingerprint
 Can be used to
separate components of a
complex drug mix
ID of Marijuana
 Based on botanical
features
 Cystolithic hairs – short
hairs, shaped like bear
claws
 DuQuenois-Levine color
test
 Without leaf, TLC is used
Collection & Preservation of
Drug Evidence
 Original container
 Airtight container if glue sniffing
 Packages marked
 Background information