Drugs and Poisons Analysis3

8/21/2019 Drugs and Poisons Analysis3

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Analysis of Drugs and Poisons

There is no sharp distinction between drugs, narcotics, and poisons! A drugis

considered to be any substance used as a medicine internally or externally. It can have an effect

on the function or structure of living tissue through various chemical reactions. Some drugs are

habit-forming and are classified as narcotics. These drugs usually relieve pain and induce sleepand can cause death when taken in excess. Consequently, they are regulated by Federal law. All

drugs that are covered by law and are restricted in some manner are called controlled drugs.Whenever a drug of any type is taken in excessive amounts and causes illness or death, it

exhibits toxic properties and is then classified as a poison.

An apparent deliberate poisoning, a homicide, an accidental death, or a suicide can allinvolve drug consumption. If a victim is found unconscious at the scene, it is important to

determine as fast as possible if a drug or poison was administered to the victim and what that

substance is! Thus, the crime scene needs to be carefully searched for evidence: empty glasses,

milk or wine bottles, or medicine containers; traces of powder or liquids on the victims body,clothes or possessions, or on the carpet or floor nearby; suspicious material in the trash. It is

easier to determine what poisoned a victim by examining an empty container than to have toexamine the victims body parts.

When a person is arrested for possession or sale of illegal drugs, analysis is needed todetermine if the confiscated material is a controlled drug, and not just an over-the-counter drug.

Forensic chemists must continuously develop new methods for analyzing drugs and poisons to

keep up with the modern drug industry and with the criminals who make and sell their owndrugs. As soon as a pharmaceutical company produces a new drug, it sends a sample to the FBI

Crime Lab. Tests are developed to identify both large and minute quantities of the substance and

results are placed on file for use as a reference when unknown samples are analyzed. Many

techniques are used to test drugs and poisons, including chromatography (gas, paper, and thinlayer), spectrophotometry (ultraviolet and infrared), and spot tests using certain chemical

reagents.

I. Over-the-Counter Drugs

Many socially accepted over-the-counter drugs can cause accidental poisoning or evendeath, especially in children. These drugs include alcohol, antacids, aspirin, nicotine, and pain

relievers. It is important to identify these substances as soon as possible so measures can be

taken to help save the victims life.One of the first synthetic pain relievers was salicylic acid. Although it was a good pain

reliever, it had a sour and irritating taste. One of its derivatives, acetylsalicylic acid, has replaced

it and is now the most widely used drug in the world: aspirin! Because it is acidic, it can irritate

the stomach. Some brands of aspirin contain other substances: antacids, caffeine, etc.An acidified solution of ferric nitrate can be used to detect the presence of aspirin in an

unknown powder. The aspirin hydrolyzes to form salicylic acid and acetic acid, and the ferric

ion reacts with the salicylic acid to form a compound with a specific purple color.


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Acetaminophen, available as Tylenol

, is also a good pain reliever. It is not acidic and can be

used by those who are allergic to aspirin.

Antacids are slightly basic compounds that are used to treat a condition of hyperacidity;

too much hydrochloric acid (HCl) in the stomach. Many of these products contain carbonateswhich react with or neutralize the acid in the stomach to produce a salt, water, and carbon

dioxide gas. Bicarbonate of soda, NaHCO3, also known as sodium bicarbonate or sodium

hydrogen carbonate, reacts in the following manner:

NaHCO3(s) + HCl(aq) NaCl(aq) + H2O(l) + CO2(g)

Alka-Seltzer

, which contains sodium bicarbonate, citric acid, and a very small amount of

aspirin, reacts with water to produce carbon dioxide gas and a buffer.

The citric acid-sodium citrate buffer reacts with excess stomach acid to relieve hyperacidity. If

too great an amount of antacid is taken, severe stomach disorders may result.

II. Controlled Drugs

Some of the drugs that have been making headlines in the news over the last few decades

include the so-called hallucinogenic drugs: LSD, marijuana, heroine, cocaine, etc. With the

exception of marijuana, these drugs are classified as alkaloids. Most are white powders.Sometimes a slight change in structure can produce compounds with quite different properties as

shown below:


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Cocaine is the main alkaloid in the leaves of the coca bush and stimulates action on the central

nervous system which allows for great physical endurance.

Most alkaloids can be identified by the colored precipitates they form with specific

reagents. Observation under various types of lighting and the results of chromatography can alsobe used to identify an unknown drug.

LSD - lysergic acid diethylamide - is the alkaloid from ergot, a fungus on rye and cereals.It can also be prepared synthetically in the laboratory. Only 50 g taken orally producespsychosis resembling schizophrenia. This drug can be found in candies, aspirin tablets, sugar

cubes, and blotting paper.

The first step in screening a suspicious hallucinogenic is to examine it under ultraviolet

light. Most hallucinogens show up as fluorescent areas. If this test is positive, the substance canthen be dissolved in an appropriate reagent and tested further. This layer chromatography can be

used to detect micrograms of the material.

Marijuana is the only mind-bender that does not contain nitrogen. It is the most widelyused illegal drug. It actually is not a drug but the dried parts of the hemp plant, Cannabis sativa.

The active component is tetrahydrocannabinol:

One of the first steps in the examination of the suspected marijuana is the visual identification

under the microscope. At the base of the leaf hairs you should be able to observe small crystals


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of calcium carbonate. If a drop of hydrochloric acid is added to the material, bubbles of carbon

dioxide gas will be produced.

CaCO3(s) + HCl(aq) CaCl2(aq) + H2O(l) + CO2(g)

A chemical test that is positive for marijuana is the Duquenois Test. When one or two mL ofDuquenois reagent is added to a sample in a test tube and shaken for a minute, the solution turnspink, the violet, and then blue upon standing. When the material is extracted with 2 mL of

chloroform, a purple or dark-blue in the chloroform layer is a positive test.

III. Identification of Heavy Metal PoisoningAlthough there are very few homicides nowadays that involve poisoning, there still are

many suicides and accidental deaths that do. The poisons can come in a variety of possibilities:car exhausts, pesticides, medicines, alcohol, industrial wastes, etc. Although lead and arsenic

have long been used as poisons, mercury, cadmium, and copper are showing up in many cases.

Our environment is full of materials that contain lead and mercury. Lead is found in

storage batteries, industrial paint, leaded gasoline, solder, ceramic glazes, and artists paintpigments. Mercury is found in electrical apparatus, thermometers, fungicides for seeds, and

industrial waste. Both of these metals can build up in the body and cause damage. Lead affects

the functioning of the blood, liver, kidneys, and brain. It will be deposited in the bones over aperiod of time. A dose of 0.5 g can be fatal.

Mercury concentrates in the brain tissues and destroys the neurons causing blindness,

convulsions, mental retardation, and even death. The fatal dose is about 1 g. Both of the heavymetal poisons damage the proximal renal tubules giving a large amount of certain amino acids in

the urine. Paper chromatography or thin-layer chromatography can be used to identify these

amino acids in the urine by comparing the chromatograms and Rfvalues with those of known

amino acids. Various samples of the same acid will have the same Rfvalues.

Rf = Distance_covered_by_the_amino_acid

Distance covered by the solvent

Lead poisoning produces alanine and -amino isobutyric acid:

Mercury poisoning produces glycine, also called aminoacetic acid.


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In order to determine which poison was administered to the victim, tests must be

conducted on the evidence found at the scene of the crime: bottles, glasses, containers, or

powders. If heavy metal poisoning is suspected, one of the first tests carried out is the Reinsch

Test. A second test then carried out is the use of dithizone, diphenylthiocarbazone.

Determination of the Identity of an Unknown Powder from the Scene

Various tests will be performed on two unknown substances and compared to the results

of the same tests on some common over-the-counter drugs found in the home or near thescene.

Materials Needed:Unknown powders A and B; aspirin; Alka-Seltzer

; sodium bicarbonate; Tylenol

;

distilled water; Universal indicator and reference chart; 0.5 M HCl; ferric nitrate solution; and

depression plates.

Procedure:1. In a horizontal row on the depression plate, place a few granules of aspirin in each of three

depressions.

2. Repeat step 1 for each of the other powders and the unknowns making sure they appear on thedepression plate in the same order as they appear on the data chart.

3. Observe the appearance of each powder, noting its color and consistency. Record

observations on the chart.4. Add about 5 drops of distilled water to one sample of each powder. Record your observations

as NVR or gas produced. Stir the sample with a stirring rod.

5. Add one drop of Universal indicator to the samples containing water from step #4. Record

the color and the pH of each sample. Stir the sample.6. Add one or two drops of the hydrochloric acid solution to each of the powders in the next

column on the plate. Record observations as NVR or gas produced.

7. Add one or two drops of ferric nitrate solution to the last sample of each powder. Stir thesolutions. Note the color of each sample and gas produced.

8. Identify each of the unknown samples.


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I denti fi cation of Simulated Controlled Drugs

Materials Needed:

Simulated LSD; ultraviolet light; simulated marijuana; hydrochloric acid; depression plate.

Procedure:

1. Carefully shine an ultraviolet light on the bag containing the simulated LSD. Do not removethe sample from the bag.2. Place a few granules of the simulated marijuana in a depression plate. Add a drop of

hydrochloric acid to the granules. Carefully rinse off the plate in the sink.

Detection of Heavy Metal Poisoning

Materials Needed:

Unknown metal poison; lead solution; mercury solution; potassium chromate; potassium iodide;

depression plate; amino acid solutions; chromatography tubes; chromatography paper;developing solution; unknown simulated urine solution; ninhydrin solution; capillary tubes;

oven.

Procedure:1. Obtain three strips of chromatography paper. Draw a pencil line across each strip about 1 cm

from the bottom of the paper. Mark a G at the top of one strip, an A at the top of the second,

and a U at the top of thethird strip.2. Use a capillary tube to place a drop of glycine the size of the typewriter letter o on the paper

you marked G. Place the drop in the center of the pencil line.

3. Repeat step #4 using the alanine and unknown solutions.4. Obtain a chromatography tube and place a small amount of solvent in the tube. The solvent

should be no higher than 0.5 cm in the tube.

5. Carefully place one of the chromatography papers into the tube and cover the tube with a

small piece of paper. Allow the solvent to travel at least half-way up the strip. Remove the stripand repeat the procedure with the other two strips.

6. Allow the strips to dry on a piece of paper towel. Once they are dry use a capillary tube to

apply ninhydrin solution (in the fume hood) until the strips have been covered. Allow the stripsto dry in the oven. Identify the type of metal poisoning in the unknown liquid and detected in the

urine.

7. Place two drops of lead solution into two wells in the depression plate. Add two drops ofpotassium chromate to one sample and two drops of potassium iodide to the other sample.

8. Repeat step 7 using the mercury solution and unknown metal solution in place of the lead

solution.

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Drugs and Poisons Analysis3