Intro to Forensic Science (1).pdf

Chapter 12: Drug ( Current Edition) Introduction A drug can be defined as natural or synthetic substance that ia used to produce physiological or psychological effects in humans or other higher order animals Psychological dependence stems from conditioned use of a drug caused by emotional needs Phys...

Chapter 12: Drug ( Current Edition) Introduction A drug can be defined as natural or synthetic substance that ia used to produce physiological or psychological effects in humans or other higher order animals Psychological dependence stems from conditioned use of a drug caused by emotional needs Physical dependence is a physiological need for a drug brought about by reugualr use and characterized by withdrawal sickness when drug administration abruptly stops The common denominator that characterizse all types of repeated drug use is the creation of psychological depencde for continued use of the drug The common denominator that characterizes all types of repeated drug use is the creation of psychological dependence for continued use of the drug The deisfre to avoid withdrawal sickness ultimately causes physical dependce or addiiciton Marijuana and cocaine are common drug of abuse whose reguaor use does not lelad to physical dependence Narcotics The regular use of a narcotics drug will invariably lead to physical dependence The most common source for these narcotic drug is opium, extracted from poppies Narcotic Drugs Narcotic drugs are analgesics, meaning they relieve pain by a depressing action on the central nervous system. This effectsfunctions such as blood pressure, pulse rate and breathing rate. Opiates Morphine is readily extracted from opium and is used to synthesize heroin Addicts frequently dissolve heroin in water by heating it in a spoon, and then inject in the skin Heroin produces a “high” that is accompanied by drowsiness and a sense of well-being that generally last for three to four hours Codeine is also present in opium, but it is usually prepared synthetically from morphine OxyCDontin, with the active ingredient oxycodone is not derived from opium or morphine but does have the same physiological effects on the body as do opium narcotics. OxyContin is prescribed to a million patients for treatment of chronic pain Methadone is another well-known synthetic opiate,, which is pharmacologically related to heroin, it appears to elimate the addicts desire for heroin while proudcing minimal side effects Morphine and Analogs Codeine and Heroin are more reactive than morphine. Why? Hallucinogens Another class of drugs is hallucinogens; marijuana is the most well-known member of this class Hallucingneges cause marked changes in normal thought processes, perceptions and moods Marijuana is the most controversial drug in this class because its long-term effects on health are still largely unknown Marijuana Marijuana refers to a preparation derived from the plant Cannabis The chemical substance largely responsible for the hallucinogenic properties of marijuana is known as tetrahydrocannabinal or THC The THC content of Cannabis varies in differenet parts of the plant, generally decreasing in the following sequence; resin, flowers, leaves, with little THC in the stem, roots or seeds The chemical substance largely responsible for th hallucingenic properties of marijuana known as tetrahydrocannabino or THC Lysergic Acid Diethylamide- LSD SD- most widely known hallucinogen, synthetically derived from a fungus, ergot. Highly potent! 25 micrograms is enough to cause vivid hallucinations! Powerful psychoactive drug. Synesthesia- Sound appearing as hallucinatory visions ( I clapped my hands & saw sound waves passing before my eyes! Anomalous blending of senses...unusual perception of things Albert Hoffman in 2006 Other Hallucinogens Phencyclidine is often mixed with other drugs such as LSD or amphetamine and is sold as a powder (“angel dust”), capsule or tablet Oral intake of PCP first leads to feelings of strength and invulnerablity which may turn to depression, tendencies toward violence and suicide Depressants Depressants are another class of drugs Depressants are substances used to depress the functions of the central nervous system Depressants calm irritability and anxiety and may induce sleep These include alcohol (ethanol), barbiturates, tranquilizers, and various substances that can be sniffed, such as airplane glue, model cement, or aerosol gas propellants such as freon. Alcohol (ethyl alcohol) enters the body’s bloodstream and quickly travels to the brain, where it acts to suppress the brain’s control of thought processes and muscle coordination Barbiturates, or “downers,” are normally taken orally and create a feeling of well-being, relax the body, and produce sleep. Tranquilizers, unlike barbiturates, produce a relaxing tranquility without impairment of high-thinking faculties or inducing sleep Stimulants Amphetamine and methamphetamine, often injected intravenously, cause an initial “rush,” followed by an intense feeling of pleasure. This is followed by a period of exhaustion and a prolonged period of depression. Who was the pioneering psychologist (famous) who created quite a sensation in European medical circles by describing his experiments with this drug??- Name the drug and the scientist! Crack is cocaine mixed with baking soda and water then heated Crack is often smoked in glass pipes, and like cocaine stimulates the brains pleasure center Cocaine is “snorted” (Inhaled) or injected into the bloodstream When combined with heroin-a dangerous micture called “spreedball” is obtained Cocaine Cocaine extracted from the leves of erythroxylin coca, causes increased alertness accompanied by suppression of hunger, fatigue and boredom Cocaine is an ionic salt that is water soluble. Crack cocaine is a neutral molecule that is insoluble in water. Cocaine is an amine ( base- B) that is extracted from crushed leaves of coca plant by treating with hydrochloric acid ( HCl). B(not water soluble) + HCl BH+Cl- (water soluble) BH+Cl- + NaHCO3 B + NaCl + H2O + CO2 Cocaine Steps in producing various forms of cocaine from raw coca plant 1. Soak coca leaves in chemical solvents so that cocaine can be drawn out of plant material. 2. Crush leaves and alcohol added through to remove extraneous matter. 3. After several washings and kerosene treatment a cocaine yield of 60% obtained. This is coca paste. 4. This coca paste is not water soluble and therefore not injected into bloodstream 5. Then treatment with acid gives ionic hydrochloride salt which is water soluble. 6. Free base- form or crack obtained by treatment with baking soda Neurotransmitters work as Chemical Messengers 1: On picking up an impulse, a nerve cell releases neurotransmitters into the synaptic area. 2. Neurotransmitters migrate to a second nerve cell and bind to receptor sites. 3. Receptor site binding results in production of a signal in the second cell. 4. Neurotransmitters are released from receptor sites and can travel back to original Cell. Half Life Half Life is the amount of time required for one half of a substance to react. In pharmaceuticals, the half life is how long it takes for one half of the drug to be eliminated from the body. So, for drug like aspirin which has a half life of 3hrs we can expect the following concentration profile : 500mg 250mg 125mg 62.5mg 31.25mg 15.63mg 7.81mg So aspirin underwent 6 half lives or 6x3= 18hr ; so at end of 18hr, aspirin is practically Gone. Half Life of some drugs……. Half life of caffeine is 4hrs Half life of nicotine is 2.5hr Craving for a cigarette versus craving for a cup of coffee?? Which is greater? Half life of cocaine before it is metabolized is only 45 minutes! Half life of THC ~ 19 hrs- total clearance of THC and metabolites involve ~ 2 weeks. Half Life of LSD ~ 3hrs Club Drugs The term club drugs refers to syntheic drugs thata re used at nightclubs, bars and raves (all-night dance parties) Substances that are often used as club drug include but are not limited to DMA (Ecstasy), GHB (gamma hydroxybutyrate), Rohypnol (“Roofies”), ketamine, and methamphetamine. GHB and Rohypnol are central nervous system depressants that are often connected with drug-facilitated sexual assault, rape, and robbery. Methylenedioxymethamphetamine, also known as MDMA or Ecstasy, is a synthetic mind-altering drug that exhibits many hallucinogenic and amphetamine-like effects. Ecstasy enhances self-awareness and decreases inhibitions, however, seizures, muscle breakdown, stroke, kidney failure, and cardiovascular system failure often accompany chronic abuse. Ketamine is primarily used as a veterinary animal anesthetic that in humans causes euphoria and hallucinations. Ketamine can also cause impaired motor functions, high blood pressure, amnesia, and mild respiratory depression. Anabloci Steroids Yet another category of drugs is the anabolic steroids. These are synthetic compounds that are chemically related to the male sex hormone testosterone. Anabolic steroids are often abused by individuals who are interested in accelerating muscle growth. Drug- Control Laws The U.S. federal law known as the Controlled Substances Act will serve to illustrate a legal drug- classification system created to prevent and control drug abuse. This federal law establishes five schedules of classification for controlled dangerous substances on the basis of a drug’s potential for abuse potential for physical and psychological dependence medical value Schedules of Classification Schedule 1 drugs have a hgih potential for abuse and have no currently accpeted medicsl use such as heroin, marijuane, methaqualone and LSD Schedule II drugs have a high potential for abuse and have medical use with severe restrictions such as cocaine, PCP, and most amphetamine and barbiturate prescriptions. Dronabinol, the synthetic equivalent of the active ingredient in marijuana is placed in schedule II by virtue of its use in treating glaucoma and chemotherapy patients. Schedule III drugs have less potential for abuse and a currently accepted medical use such as all barbiturate prescriptions not covered under Schedule II, such as codeine and anabolic steroids. Schedule IV drugs have a low potential for abuse and have a current medical use such as darvon, phenobarbital, and some tranquilizers such as diazepam (valium) and chlordiazepoxide (librium). Schedule V drugs must show low abuse potential and have medical use such as opiate drug mixtures that contain nonnarcotic medicinal ingredients. Drug Identification The challenge or difficulty of forensic drug identification comes in selecting analytical procedures that will ensure a specific identification of a drug. This plan, or scheme of analysis, is divided into two phases. Screening test that is nonspecific and preliminary in nature to reduce the possibilities to a manageable number. Confirmation test that is a single test that specifically identifies a substance. Preliminary Analysis Faced with the prospect that the unknown substance may be any one of a thousand or more commonly encountered drugs, the analyst must employ screening tests to reduce these possibilities to a small and manageable number. This objective is often accomplished by subjecting the material to a series of color tests that will produce characteristic colors for the more commonly encountered illicit drugs. Drugs when brought into contact with specific chemical reagents yield typical colors Color Tests Marquis Test for opium derivatives reagent turns purple in presence of heroin & opium derivatives Turns orange brown with amphetamines Dillie Koppanyi test- barbiturates turn blue Duquenois Levine- for marijuana yields a purple color Scott test for cocaine- solution of cobalt thioscyanate turns blue, on addition of HCl, turns colorless or light pink.On adding chloroform, blue color reappears Van Urk reagent turns blue-purple in presence of LSD Preliminary Analysis Microcrystalline tests can also be used to identify specific drug substances by studying the size and shape of crystals formed when the drug is mixed with specific reagents. Another consideration in selecting an analytical technique is the need for either a qualitative or a quantitative determination. The former relates just to the identity of the material, whereas the latter requires the determination of the percent composition of the components of a mixture. Confirmaitonal Determination Once this preliminary analysis is completed, a confirmational determination is pursued. Forensic chemists will employ a specific test to identify a drug substance to the exclusion of all other known chemical substances. Typically infrared spectrophotometry or gas chromatography-mass spectrometry is used to specifically identify a drug substance Chromatography The theory of chromatography is based on the observation that chemical substances have a tendency to partially escape into the surrounding environment when dissolved in a liquid or when absorbed on a solid surface. Those materials that have a preference for the moving phase will slowly pull ahead and separate from those substances that prefer to remain in the stationary phase Imagine a beaker of water covered, and as molecules escape into surrounding air, they hover/accumulate over water layer. Random motion brings them back to water. Eventually, a point is reached when # molecules leaving water = # molecules returning. At this time, liquid and gas phases are said to be in equilibrium. When a volatile compound is dissolved in a liquid and brought to equilibrium with air, there is a fixed ratio between the concentration of volatile compound in air and its concentration in the liquid, and this ratio remains constant for a given temperature The distribution of a gas between the liquid and gas phases is determinedby how easily the gas dissolves in the liquid Chromatography is a means of separating and tentatively identifying the components of a mixture. Blue molecules have greater affinity for upper phase and hence will be pushed along a faster rate by moving air.. Analogous to race between chemical compounds. Chromatography is one of the most valuable techniques biochemists have for separating mixtures. It can be used to determine the ingredients that make up a particular flavor or scent, to analyze the components of pollutants, and to find traces of drugs in urine. Chromatography is used by Forensic Scientists! Food scientists also use chromatography to determine if colours used are legal for use TLC uses a solid stationary phase usually coated onto a glass plate and a mobile liquid phase to separate the components of the mixture. TLC is a rapid, qualitative analytical method. The properties of the adsorbent and solvent are used to pull the components up the plate The liquid will slowly rise up the plate by capillary action causing the sample to become distributed between the stationary phase and the moving liquid phase. Because most compounds are colorless, the materials must be visualized by placing the plates under ultraviolet light or spraying the plate with a chemical reagent. The distance a spot travels up a thin-layer plate can be assigned a numerical value known as the Rf value. The Layer Chromatography- Drug Samples The distance tthe suspect sample sn standard sample move up are compared to and if they are same, they can be tentatively identified In TLC, the mobile phase is a liquid and the stationary phase is a thin solid coating such as silica gel on a glass plate. The mixture to be separated is spotted on bottom of the stationary phase. The plate is then placed upright in a closed chamber containing the select liquid (mobile phase or solvent), but the liquid must not touch sample spot. Liquid then rises up the plate via capillary action. As liquid rise up plate, the components of sample get distributed between stationary solid phase and moving liquid phase Fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. The most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can only be seen when exposed to UV light Gas Chromatography In GC, the moving phase is actually a gas called the carrier gas, which flows through a column 1. Sample introduced via syringe into injection port 2. A stream of nitrogen gas flows through injector carrying sample into column 3. Here we have a thin film of liquid 4. Here sample is separated in column and carrier gas and separated components emerge from column & enter detector. 5. Signals developed by detector activate recorder 6. The recorder produces a trace of separation with elution time & peak area gives concentration. The stationary phase is a thin film of liquid contained within the column. After a mixture has traversed the length of the column, it will emerge separated into its components. Unknown mix identified by comparing its retention times with mix of barbiturate The written record of this separation is called a chromatogram. The time required for a component to emerge from a GC column is known as retention time. GC is widely used because it can resolve a complex mixture into its components within minutes. It is very sensitive and can detect & quantitate materials at nanogram level. Mass Spectrometry These positive ions almost instantaneously decompose into numerous fragments, which are separated according to their masses. The unique feature of mass spectrometry is that under carefully controlled conditions, no two substances produce the same fragmentation pattern. GC AND MASS A direct connection between the GC column and the mass spectrometer allows each component to flow into the mass spectrometer as it emerges from the GC. Mass Spectrometry In the mass spectrometer, a beam of high-energy electrons collide with a material, producing positively charged ions. GC and Mass The separation of a mixture’s components is first accomplished by the GC. Then, fragmentation of each component by high-energy electrons in the mass spectrometer, will produce a distinct pattern, somewhat like a “fingerprint”, of the substance being examined Spectrophotometry Just as a substance can absorb visible light to produce color, many of the invisible traditions of the electromagnetic spectrum are likewise absorbed Spectrophotometry an important analytical tool, measure shte quanty of radiation that a [articular material absorbs as a function of wavelength and frequency The quantity of light absorbed at any frequency is directly proportional to the concentration of the absorbing species. This is known as Beers Law UV and IR Spectrophotometry Currently most forensic laboratories use UV and IR spectrophotometers to characterize chemical compounds The simplicity of the UV spectrum facilaltes its use as a tool for determining a materials probable identity, although it may not provide a definitive result The IR spectrum provides a far more complex pattern UV and IR Spectrophotometry Different materials always have distinctively different infrared spectra; each IR spectrum is therefore equivalent to a “fingerprint” of that Substance. The Spectrophotometer The spectrophotometer is the instrument used to measure and record the absorption spectrum of a chemical substance The compounds of a spectrophotometer are: -A radiation source -A monochromator or frequcney selector -A sample holder -A detector to convert electromagnetic radiation into an electrical signal -A recorder to produce a record of the signal Aborption spectra can be done in the visible, ultraviolet (UV) or infrared (IR) regions Collection and Preservation The field invetiaor has the responsibility of ensuing that the evidence is properly packaged and lableed for the laboratory Gnerally common sense is the best guide keeping in mind that the package must prevent the loss of the contenct and or cross contamination Often the original container in which the drug was seixed will suffice All packages must be marked with information that is sufficient to ensure identification by the officer in the future and establish the chain of custody