Forensic Science: An Introduction

Drugs and Toxicology

Dependence

Drug – natural or synthetic substance used to produce a physiological or psychological effect.

Psychological dependence – emotional attachment to the drug

Physical dependence – physiological need characterized by withdrawal sickness if not taken

Narcotics

Depresses vital body functions Physical – yes Psychological – high Opiates - Morphine,Heroine,Codeine Synthetic Opiates - Methadone,OxyContin

Hallucinogens

Induces changes in normal though and moods

Physical – no Physiological – only PCP Marijuana ( THC), Hashish LSD PCP

Depressants

Slows down functions of the CNS Physical - yes Psychological – varies Alcohol Barbituates (Quaaludes) Antipsychotics/anxiety (Valium) Huffing materials

Stimulants

Speeds up the CNS Physical – only nicotine Psychological – varies Amphetamines – speed Methamphetamines (crsytal meth) Cocaine/crack

Others

Club Drugs GHB, Rohybinol (Roofies) - depressants Ecstacy, ketamine – stimulants/hallucogens

Anabolic Steroids

Controlled Substance Act Schedule I – no current medical use; heroin,

marijuana, methaqualone, LDS Schedule II – current medical use; high

dependence; opiates not in Sch I, cocaine, methadone, PCP, most amphetamines, most barbituates

Schedule III – less potential for abuse, current medical use; low-mod phys abuse; codeine, anabolic steroids, barbs not Sch II

Schedule IV – low potential for abuse; tranquilizers, Valium,

Schedule V – low abuse and dependence; opiate drug mixtures with nonnarcotic medicinal ingredients

Drug Analysis

Screening – preliminary test used to reduce the number of possible identities of unknown substances

Confirmation – a single test that specifically identifies a substance

Qualitative – determines the identity of the substance

Quantitative – determines the amount of the substance

Color Tests

Marquis – heroine, morphine, opiates (amphetamines, methamphetamines Dillie-Koppanyi – barbiturates

Duquenois-Levine – marijuana Van Urk – LSD Scott Test – cocaine Microcrystalline Tests – a chemical test

that creates crystals when added to the drug. The size and color identifies the substance.

Chromatography

Molecules in a mobile phase are attracted to a stationary phase and are thus separated out of a mixture.

TLC – stationary phase is a gel-coated plate GC –mobile gas phase moves over a

stationary liquid phase in a column Uses retention time to identify substances

and has the sensitivity to detect at a nanogram level.

Spectrophotometry

Identifying a substance by the way it absorbs selected wavelengths of light

Absorption spectrum Beer’s Law UV spec – establishes a probable identity by

eliminating others IR spec – complex enough for specific

identification Mass spec – paired with GC; provide fingerprint via

fragmentation patterns of a substance

Toxicology

Toxicology – the detection and identity of drugs and poisons in the body fluids, tissues and organs Absorption – passage across the wall of the stomach

and small intestine into the blood stream Distribution – where the substance travels and has its

effect once in the blood Metabolism – the alteration of a substance into other

chemicals in the body in order to eliminate it Elimination – how the body gets rid of the substance

and/or its metabolites Toxicity – the impact the drug or poison has on the

body

Alcohol

Absorbed quickly into all watery portions in the body

BAC is affected by time of consumption, type, food in stomach, etc

Eliminated by oxidation (into CO2 and water) or excretion (breath, urine)

BAC determined by analyzing blood or breath Henry’s Law - 2100:1 ratio of alcohol in the

blood to alcohol in alveolar air( 1 ml of blood has as much alcohol as 2100 ml of alveolar air)

Blood is collected with anticoagulant and a preservative

Police In the Field

Field sobriety testing – psychophysical tests Horizontal-gaze nystagmus – eye jerking on

a side to side movement Walk and turn and one-leg stand tests are

divided attention tasks Breathalyzer Legal BAC – less than 0.08% or DWI/DUI Implied consent

Toxicologist

Must detect very small amounts of a drug that most likely has been metabolized and then determine its toxicity

Specimens collected by medical examiner or physician

Blood (1-10 ml) Urine (1-2 voids) Hair (long-term use) Cocaine, alcohol, and marijuana make up 90% of

the drugs encountered in a tox lab

Techniques

Acid-base extraction – allows extraction and categorization of some drugs

Screening tests – TLC, GC, immunoassay Confirmation tests – GC/MS

Non-drug poisons

Heavy metals – As, Bi, At, Hg, Th Screen with Reinsch test – X + HCl + Co Confirm – emission spec or X-ray diffraction CO – suicide or murder, percent saturation

of CO in blood, outcompetes O2 in blood

Toxicologist must assess

drug’s influence on the behavior of the individual

determine past history with drug possible drug interactions