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 Tests1. 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