Chemical Testing and Identification Quiz

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Questions and Answers

What does a color change in a chemical test indicate?

The presence of impurities in the sample

No reaction occurred between substances

A successful reagent interaction (correct)

A permanent alteration in physical state

Which type of sample is often found in a blotter paper or gel windows?

LSD (correct)

Cocaine

Heroin

Methamphetamine

Why is a blank or negative control included in chemical testing?

To ensure that the reagent is not contaminated (correct)

To validate the presence of colorants

To enhance color stability

To compare reagent reaction with known substances

What allows visible light to facilitate an electron promotion in a chemical reaction?

Energy difference between molecular orbitals Signup and view all the answers

What is a common characteristic of tan powders in substance identification?

They often contain heroin and methamphetamine. Signup and view all the answers

What is the significance of green plant material in drug testing?

Unlikely to test for cocaine or heroin initially. Signup and view all the answers

Which substance is least likely to be indicated by green plant materials?

Cannabis Signup and view all the answers

What is NOT a common characteristic of narcotic drugs?

Immediate improvement in memory. Signup and view all the answers

Which of the following is a common misconception about narcotic drugs?

They can be safely used without prescription. Signup and view all the answers

In drug testing, why is it crucial to identify the type of material present?

To accurately interpret the results of the test. Signup and view all the answers

Which of the following statements best describes narcotic drugs?

They have therapeutic effects and potential for abuse. Signup and view all the answers

Which is an important factor to consider when interpreting drug tests?

The type of detection method used. Signup and view all the answers

What is a primary reason for testing substances in relation to narcotics?

To distinguish between legal and illegal use. Signup and view all the answers

What role does HAuCl4 play in the sample testing process?

It acts as a precipitating reagent. Signup and view all the answers

What is the effect of adding a strong base to the sample?

It precipitates certain compounds in the sample. Signup and view all the answers

What is the first step in the sample testing process described?

Placing the precipitating reagent on a coverslip. Signup and view all the answers

Which reagent is combined with HAuCl4 for the testing?

H3PO4 Signup and view all the answers

Where is the strong base added in the testing procedure?

On the precipitating reagent placed on the coverslip. Signup and view all the answers

What is used to view the sample after the reagents have been added?

A microscope Signup and view all the answers

How is the coverslip positioned during the test?

Inverted over a small portion of the sample. Signup and view all the answers

What is the significance of the class cylinder mentioned in the content?

It helps in measuring reagent volumes accurately. Signup and view all the answers

Signup and view all the answers

Study Notes

Chemical Analysis of Narcotics in Forensic Laboratories

The presentation discusses chemical analysis of narcotics in forensic labs.
A chemical equation is provided: 2KNO₃ + H₂CO₃ → K₂CO₃ +2H₂O

What is a Drug?

A drug is a substance that, when ingested, induces a physiological change.
Drugs can be ingested by swallowing, injection, inhalation, or absorption through the skin.
All drugs are toxic; the dose differentiates a therapeutic drug from a poison.
Drugs are used to treat or prevent disease, alleviate pain, promote sleep, and induce physiological responses.
Paracelsus (1493-1541) stated, "All substances are poisons; the right dose differentiates a poison from a remedy."

Definition of a Drug

A substance that, when ingested, can cause a physiological change.
Modes of ingestion include swallowing, injection, inhalation, and skin absorption.
Toxicity: The dosage determines whether a drug is beneficial or harmful.
Uses: Treating diseases, relieving pain, promoting sleep, and influencing physiological processes.
Drugs are often used interchangeably with medicines.

Drug Abuse

Drug abuse changes over time and varies across societies.
Cocaine was once included in Coca-Cola, initially for stimulant and aphrodisiac purposes, but it was removed due to addiction concerns by 1929.
Drugs like LSD and MDMA were historically utilized in psychotherapy.
Methamphetamine use was significant among American soldiers from WWII to the Gulf War in 1991.
Marijuana had medicinal uses in ancient times, including for glaucoma, anorexia, and chemotherapy-induced nausea.
The active ingredient in marijuana is now synthetically prepared and marketed as Marinol.

Classification of Drugs and Categories

Classification of drugs can be based on origin and function, general effect, use, schedules, and acid-base character.

Classification by Origin

Natural products are extracted from plants.
Examples include alkaloids such as caffeine, opiates, cocaine, and THC.
Semisynthetic compounds are made by modifying natural products.
Examples include heroin, derived from morphine, and hormones, steroids.
Synthetic compounds are fully synthesized in laboratories, examples include Diazepam (Valium®) and synthetic THC (Dronabinol).

Classification by General Effect

These lead to five groups: analgesics, depressants, hallucinogens, narcotics, and stimulants
Drugs are not limited to a single category; some drugs can fall into multiple categories

Analgesics

Analgesics relieve pain.
Common examples include aspirin, NSAIDs (ibuprofen and naproxen sodium), and morphine.
NSAIDs work by reducing fever and inflammation.
Morphine and opiates act on opioid receptors in the central nervous system (CNS).
Aspirin reduces inflammation and pain but does not produce euphoria and is non- addictive.
Morphine can cause euphoria and deep relaxation but is addictive and categorized as a narcotic.

Depressants

Depressants reduce central nervous system (CNS) functions.
Examples include barbiturates, tranquilizers, sleep aids, and ethanol.
Benzodiazepines, introduced in the 1960s, interact with GABA receptors, inhibiting CNS responses.

Hallucinogens

These drugs alter perception of time and reality, affecting movement, thought, perceptions, vision, and hearing.
Examples include LSD, mescaline, marijuana, and high-dose stimulants like meth.
Some drugs act as hallucinogens at high dosages.
These have complex mechanisms, broadly classified into phenethylamines or tryptamines.

Narcotics

Narcotic effects relieve pain and promote sleep, derived from opium plant alkaloids.
Examples include morphine, codeine, heroin, hydromorphone, oxycodone, and hydrocodone.

Stimulants

Stimulants have effects opposite to narcotics and depressants. They increase CNS function, resulting in alertness and sleep disruption
Examples include cocaine, amphetamine, and methamphetamine.
High dosages of stimulants can result in hallucinogenic effects.
Stimulants affect dopamine, serotonin, and norepinephrine reuptake leading to increased stimulation and potentially hallucinogenic responses.

Classification by Use

Classification is based on how drugs are used and abused.
Includes predator drugs (used to incapacitate), club drugs (common for young people), human performance drugs (to enhance performance), and inhalants.

Predator Drugs

Commonly known as date-rape drugs.
Used to incapacitate for sexual purposes.
Examples include Ketamine, Rohypnol, GHB, and related compounds.
Effects range from disorientation to unconsciousness, and loss of short-term memory is common.
Victims may have no recollection of the event or hours leading up to it.

Club Drugs

Commonly used at parties and clubs by young people.
Often overlap with predator drugs in characteristics.
Examples include Ecstasy (MDMA), LSD, psilocin mushrooms, Phencyclidine (PCP), and methamphetamine.

Human-Performance Drugs

These drugs consist of substances improving or impairing performance, often abused by athletes.
Anabolic steroids, derived from testosterone, are examples, increasing muscle mass and decreasing recovery time.

Inhalants

Inhalants are substances inhaled to produce desired effects.
Examples include paint thinners, nitrous oxide (laughing gas), gasoline, and nail polish.
Generally have depressant effects similar to alcohol.

Classification by Schedule

Legal classification of drugs is closely tied to their chemical and physiological properties.
Drugs of abuse are subject to regulations and laws due to their potential for abuse and harm.
Physical and psychological dependences are considered.
Physical dependence is due to biochemical or physiological changes from repeated use, manifesting as withdrawal symptoms, tolerance etc..
Psychological dependence is due to emotional or psychological needs, not directly physiological.

Drugs as Evidence: The Five Ps

Common forms of drug evidence include powders, plant matter, pills, precursors, and paraphernalia.

Profiling (Chemical Fingerprinting)

Drug profiling examines a drug sample beyond simple identification, categorizing, determining common origin, elucidating synthetic routes, and identifying diluents, adulterants, and impurities.
The method is increasingly important in investigations, and it is crucial for forensic work.

Profiling a Drug Sample

Physical examination (color, appearance, particle size) and analysis.
Isotopic ratios, which indicate environmental conditions during plant cultivation, and other constituents.

Coextracted Components

Plant-derived drugs are often extracted along with precursors and other impurities, such as alkaloids in opium or morphine. These impurities, such as codeine, thebaine, and papaverine, are frequently co-extracted with morphine.

Impurities

Impurities are introduced during processing, from reagents, contaminated glassware, or water.
Solvents can also be contaminants, and residual solvents may be present in the final product.

Adulterants and Diluents

Adulterants and dilutents appear in drug batches/groups in varying amounts. Identifying these substances in a drug sample is usually time consuming, especially those with microscopic similarities to other substances.

Aspects of Profiling a Drug Sample

Physical characteristics (appearance, color, particle size). Chemical analysis (major and minor components, drug and related substances, impurities).

Presumptive Color Tests

86% of laboratories use presumptive tests (spot tests) for initial drug analysis.
Tests include Duquenois-Levine (marijuana), cobalt thiocyanate (cocaine), Marquis (opiates, amphetamines), p-Dimethylaminobenzaldehyde (LSD), and other color tests.

Considerations for Color Tests

Color tests are performed on unknown substances if there is enough of a sample.
Color tests are usually qualitative, offering information about specific compounds and functional groups.
Color change, quantity, intensity, etc. indicate chemical reaction characteristics. The results are specific and can be used to exclude some compounds from further analysis.

Spot Plate/Test Tube

Spot plate and test tube tests are common in forensic drug analysis.
Used to obtain results that are relatively easy to see/detect, such as with a white or black background.
A procedure for these tests would involve careful measuring, mixing, and observing.
Controls for blanks/negative controls are included for analysis.

Colorants

Substances that emit/absorb energy in the visible spectrum, dyes, pigments, etc.
Color change indicates a chemical reaction/modification, and it is possible to identify and separate various components in a batch of products.

Molecular Orbital Transitions

Molecular structures affect color; covalently bonded compounds form molecular orbitals, impacting visibility.
Absorption patterns create a visual representation of the substance; color/intensity variations result from absorbed wavelengths.

Chromophores

Specific portions of molecules that are responsible for color.
Transition metals, oxygen, and nitrogen molecules modify chromophores, modifying color/intensity and creating specific color patterns.
Changes to molecules affect electron transitions and/or color intensity.

Auxochromes

Chemical groups that modify a chromophore's color or absorption intensity.

Intensity of Color

Increased conjugation of molecules enhances the intensity of color/absorption.
Hypsochromic and bathochromic shifts affect light absorption patterns.

Dyes and Dye Formation

Pigments are insoluble materials suspended in a solvent.
Dyes are colorants dissolved in a solvent, with differences in chemical solubility determining whether a substance is a pigment or a dye.

Other Structural Features

Presumptive tests frequently produce colored substances composed of carbonium ions (carbocations).
Carbocation stability can be influenced by substitution patterns or conjugation effects.

Marquis Test

Formaldehyde reacts with certain molecules to produce colored precipitates or colored substances.
Formaldehyde's reaction with primary or secondary amines and other compounds are distinctive.
Color change intensity and specificity.

Ehrlich's Test

p-Dimethylaminobenzaldehyde (p-DMAB) reacts to form a stable carbocation when subjected to certain conditions, allowing for detection of LSD and related compounds.

Liebermann Test

A chemical test for phenol groups, it uses KNO2 dissolved in sulfuric acid.
It reacts with phenols and amines. The reaction produces color change, offering insights into chemical structures and properties.

The Duquenois Test

This test determines if a sample includes marijuana by reacting with tetrahydrocannabinol (THC).
The reaction results in a violet chromophore.

Transition Metals in Color-Based Presumptive Tests

Transition metals form complexes with certain drugs, which results in color changes.
pH of the environment influences color/reaction outcomes.
Cobalt thiocyanate is used to test for cocaine, which results in a blue color.

Microscopic Tests

Crystal tests involve precipitating a reagent with a target drug forming specific crystal structures.
The test is advantageous because morphology differentiates analytes and provides specificity, avoiding false positives.
Methods exploit unique solubility and volatility characteristics of target substances.

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Description

Test your knowledge on chemical testing concepts! This quiz covers topics such as color changes in tests, sample types, the importance of controls, and properties of substances. Ideal for students studying chemistry or related fields.