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FSC239 Ch 23

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Forensic Science

FSC239 December 14 th Ch. 23 – pgs 457 to 482 Analysis of Control Substances controlled substances: substances (usually drugs) whose possession or use is regulated by the government - the analysis of controlled substances is the basis of the forensic laboratory o to confirm the presence of a substance that is either statutorily regulated or is illegal to possesses deductive reasoning: using non-specific details to infer a specific fact o from general to specific – build down Standard Practices currently under development by the ASTM E-30 are: 1. WK389: Terminology relating to forensic seized drug analysis 2. WK390: Practice for identification of drugs 3. WK2238: Standard terminology relating to seized drug analysis 4. WW2239: Standard practice of education and training of seized drug analysis 5. WW2240: Standard practice for quality assurance of laboratories performing seized drug analysis 6. WW2241: Standard practice for identification of seized drugs - SWGDRUG has established 3 categories of analytical techniques o 1. Category C – non-specific techniques o 2. Category B – moderately specific techniques o 3. Category A – specific techniques - the SWGDRUG guidelines provide recommendations for the types and minimum number of tests required to identify seized drugs - minimum examination criteria is a validated Category A supported by a Category A/B/C technique - the examination of controlled substances is divided into: o botanical examinations: identify physical characteristics specific to plants  most common  done at the controlled substance section of lab  ex. marijuana, peyote, mushrooms, and opium  examiner is identifying plant material, not specific psychoactive ingredients  DNA analysis has potential applications o chemical examinations: use wet chemical or instrumental techniques to identify specific substances that are controlled by statute Marijuana - cannabis sativa l - identification is a 2-step process o 1. establishes plant/plant material as mj through physical characteristics  identification process begins with macroscopic examination of plant material (1) • has palmate leaf configuration and pinnate leaf structure with serrated edges  microscopic identification is used to identify: • cystolithic – bear claw shaped – hairs on the top surface of the leaf o 2. establishes presence of plant resin that contains psychoactive components  Duquenois-Levine test: chemical colour test used to determine the presence of mj  TLC: thin layer chromatography – separates cannabinoids in the resin  GC: gas chromatography  MS: mass spectroscopy – specifically identifies THC Hashish - not the potent form of mj - is the resin from mj that has been isolated from the plant material – oil/cake form - if the hash statutes mirror mj, a Duquenois-Levine test is all you need - if it does not, then MS is performed Peyote - small Mexican cactus lophophora williamsii - identification begins with macroscopic examination of plant material – peyote button has a soccer ball appearance - doesn’t have specific microscopic characteristics - a chromatographic examination is used to confirm the identity of peyote Mushrooms - possession of mushrooms is not illegal - physical identification of psilocin and psilocybin is the initial step in identification - next step is the testing for the presence of psilocin and psilocybin o chemical colour tests, TLC, and examination of extracts using UV - procedure of sample is always the same o 1. screening step o 2. extraction or sample preparation step o 3. confirmatory step - chemical examinations can be divided into 2 steps o 1. wet chemical o 2. instrumental procedures Wet Chemical - used in the initial stages of the controlled substance identification process o quickly determine if a controlled substance is or is not present - consist of chemical colour tests, thin layer chromatography, and liquid extraction Chemical Colour Tests - chemical reactions that provide information regarding the structure of the
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