forensic toxicology and pharmacology

forensic toxicology

study of poisons that may have legal implications

toxicologist

drugs after ingested into body

two phase approach —> presumptive and confirmatory test

seized drug analysts

drug as physical evidence

tracking drugs in the body

ADME

Absorption

Distribution

Metabolism

Excretion

• metabolized mostly in liver

amphetamine

stimulants —> excitatory condition —> increased heart rate, blood pressure and respiratory rate

• euphoria

cocaine

stimulant —> extracted from coca leaves with HCl

—> when treated with base —> “crack” cocaine

metabolized to methylecgonine

cannabionoids

psychoactive compounds found in marijuana

tetrahydrocannabinol (THC)

a cannabinoid

—> euphoria, perceptive alterations, memory impairment, mood swings, hallucinations and delusions and paranoia

polypharmacy

using multiple prescription drugs

gas chromatography (GC)

for testing chemical components of a mixture

more than 350 mg/dL — death

cyanide poisoning

fasting acting form is gas hydrogen cyanide

death occurs within minutes

fatal level: 2500 ng/pmL

carbon monoxide poisoning

blood carboxyhemoglobin over 60% is at risk of death

testing in forensic toxicology

two step approach —> presumptive/screening and confirmatory test

confirm by finding toxins in two location (eg. blood and urine)

immunoassays

screening test —> antibodies used —> only reacts when substance is present

!! not 100% specific

thin-layer chromatography (TLC)

screening test

silica gel covered plate + extracted specimen in organic solvent —> spotted onto the plate

plate placed in tank —> mobile phase

slow moving compound —> don’t react with silica

cheap and is the primary method

gas chromatography

confirmatory test

GC + detection system

mobile phase=carrier gas = an inert gas (H, N, He)

paired with mass spectrometer (MS) —> GC-MS

retention time = how long it takes for sample to move thru column

Electron impact

ionization scheme used in MS

mass spectrometry

most common is quadruple mass filter

compound in GC ionized —> electron impact —> find molecule

liquid mass chromatography

compatible with all organic compounds (don’t have to be converted to gas form)

good for thermolabile and hydrophilic stuff

colourimetric testing

for measuring metals

• cheap

• high detection levels

• needs lots of sample

inductively coupled plasma-mass spectrometry (ICP-MS)

measures metals

• more modern

• low detection level

• small sample size

• $$$

pharmacokinetics

how a drug/ toxin moves thru the body

toxicogenomics

how genetics play a role in how toxic a drug/poison is for a person

drugs affects when taken → absorbed —> tissues —> metabolized — > relies on enzymatic activity —> can be metabolized at different rates

drug testing in dead ppl

used to find manner of death

• not studied well (ethical reasons)

• postmortem redistribution —> concentration changes that occur after death —> drugs move to different regions of the body

controlled substances act (CSA)

US code —> define use of controlled substances —> divided drugs into schedules (groups) based on potential for abuse and medical use

1984 —> allowed drug enforcement administration (DEA) to temp. add substance to schedule

schedules

Schedule I —> high potential for abuse, not accepted as medicine (heroin)

Schedule II —> high potential for abuse and have accepted medical uses (cocaine, morphine, methamphetamine)

Schedule III —> less potential for abuse and addiction (anabolic steroids, barbiturates)

Schedule IV and IV —> decreasing risk, increasing legit uses (over the counter cough medicines)

SWGDRUG

Scientific working group for the analysis of seized drugs

provides recommendations for types/min number of tests requires to identified seized drugs

3 categories for analytical techniques for identification of controlled substances

Category A —> specific examinations

Category B —> moderately specific techniques

Category C —> Nonspecific Techniques

botanical examinations

identification of controlled substances

—> identify physical characteristics specific to plants that are considered controlled substances

chemical examinations

identification of controlled substances

—> using wet chemical or instrumental techniques to identify specific substances

plant matter analysis

plant —> macro examination —> mico exam. —> chem. exam

not plant —> screening test —> confirmation test

top four botanical examination caseload

• marijuana

• peyote

• mushrooms

• opium

marijuana

cannabis sativa

identify: (2 steps)

• physical traits (—> macro and micro)

• establish presence of plant resin that has psychoactive stuff

micro. exam. —> cystolithic hairs (bear-claw shaped) on t level of lead

duquenois-levine test —> chem. colour test to confirm presence of weed in sample

hashish

resin from marijuana isolated from plant

found as oil or in cake form to be smoked

federal law (US) doesn’t care between marijuana and hashish

—> duquenois-levine test is all needed to identify

peyote

Lophophora williamsii (small mexican cactus)

has mescaline —> hallucinogenic effects

mushrooms 🍄

components within the mushroom (psilocin, psilocybin) are controlled substances

• additional step to confirm the Ps is needed

• over a dozen mushrooms types contain the Ps

• caps can be white to tan, stems off-white+bluy gray staining

chemical examinations

needs identification of specific compound within mixtures

steps (SEC)(“chem will just take a SEC lol) —> screening, extraction, confirmation

two types —>

• wet chem. —> screening methods, sample prep. (non specific)

• instrumental procedures → screening methods, confirmatory tools

chemical colour tests (chem. examinations)

chem reactions → gives info abt structure of the substance

can indicate presence of generic molecular structure

small amount of substance transferred to well and test reagent is added

+ and - controles

microcrystal tests (chem. examinations)

test samp. dissolved in solution containing reagent → reaction where nique solid crystals form

this test relies on comparison of crytals formed and those formed by reference standard → subjective

extractions (chem. examinations)

used to separate compound of interest from rest of the sample

type of extractions

• physical extraction (physically removing particles)

• dry washing

• dry extractions (solvent removes compound from sample)

• liquid extractions (utilizing solubility characteristics)

infrared (IR) spectroscopy (instrumental examination)

uses compound ability to absorb IR light → solid samples good

organic compounds absorb different portions of IR spectrum → absorbance charts→ unique → library ok known IR spectra of compounds used for comparison

clandestine drug laboratories

illegal places that make controlled substances

clandestine lab chemist → forensic chemist w/ training in clandestine manufacturing techniques