4103FSBMOL - Lecture 1 - Basic Forensic Analysis. Flashcards
Colour Tests, Microcrystalline Tests and Molecular Orbitals.
What are the 2 types of Basic Forensic Analysis Tests?
Colour Tests and Microcrystalline Tests.
What are Colour Tests also known as and what are they used for?
Presumptive or Spot Tests. They are used as a Screening Tool in Routine Drug Analysis.
What Type of Identification do Colour Tests provide?
TENTATIVE (provisional) identification.
What needs to follow a colour test to prove that it is a certain drug for example?
Give an example.
A Confirmatory Test such as GC-MS.
What is a Microcrystalline test?
They are chemical tests resulting in the formation of unique microcrystals for a given substance when combined with a specific reagent.
Name all the Different Types of Colour Test.
- Marquis Reagent Test.
- Ehrlich’s Test.
- Duquenois-Levine Test.
- Cobalt Thiocynate Test.
- Dille-Koppanyi Test.
- Simon Test.
- Libermann’s Test.
- Ferric Chloride Test.
- Iodine Test.
- Amalic Test.
- Mandelin’s Test.
- Mecke’s Test.
- Froehde Test.
- Fast Blue BB Salt Test.
What is the MAIN Colour Test you always have to start with?
The Marquis Reagent Test.
What is the Marquis Reagent Test used to detect for?
- Opoids - Heroin, Morphine, Codeine, Opium.
- Amphetamine Family - Amphetamine, Methamphetamine and Ecstasy.
- Alkaloids - e.g. Cocaine.
- Magic Mushrooms.
What is the Ehrlich’s Test used to detect?
Lysergic Acid Diethylamide - LSD.
Whats the Duquenois-Levine Test used to detect?
Tetrahydrocannabinol - THC.
What is the Cobalt Thiocynate Test used to detect?
Cocaine.
What is the Dille-Koppanyi Test used to detect?
Barbiturates.
What is the Simon Test used to detect/ distinguish between?
It is used to distinguish between Amphetamine and Methamphetamine.
What is the Libermann’s Test used to detect?
The Phenol and Amine functional groups in drugs.
What is the Ferric Chloride Test used to detect?
- Salicylates.
- Alkaloids.
- Phenols.
What is the Iodine Test used to detect?
Starch.
What is the Amalic Test used to detect?
Xanthines (e.g. Caffeine).
What is the Mandelin’s Test used to detect?
- Steroids.
- Alkaloids.
- Aspirin.
What is the Mecke’s Test used to detect?
Alkaloids (organic compound containing at least 1 nitrogen atom).
What is the Froehde Test used to detect?
- Codeine.
- Opium.
- LSD.
What is the Fast Blue BB Salt Test used to detect/ differentiate between?
It is used to differentiate between metaboiltes (THC), cannabinol and cannabidol.
What is the Marquis Reagent made up of?
2% Formaldehyde in Concentrated Sulphuric Acid.
What colour does Morphine go when the Marquis Reagent is added?
Purple.
What colour does Heroin go when the Marquis Reagent is added?
Purple.
What colour does Magic Mushrooms go when the Marquis Reagent is added?
Yellow.
What colour does Ecstasy go when the Marquis Reagent is added?
Orange to Black.
What colour does Methamphetamine go when the Marquis Reagent is added?
Orange.
What colour does Amphetamine go when the Marquis Reagent is added?
Orange-Red-Brown.
Which 2 drugs go purple when the Marquis Reagent is added?
Morphine and Heroine.
What drug goes Yellow when the Marquis Reagent is added?
Magic Mushrooms.
What drug goes Orange to Black when the Marquis Reagent is added?
Ecstasy.
What drug goes Orange when the Marquis Reagent is added?
Methamphetamine.
What drug goes Orange-Red-Brown when the Marquis Reagent is added?
Amphetamine.
How does the Mechanism work in the Marquis Reagent Test?
The Formaldehyde (CH2O) structure reacts with the Benzene Ring part of the structure to form an unstable Primary Carbocation. Another of the same molecule is added and this results in a secondary carbocation which is a stable dimer.
What Reagents are used in the Ehrlich’s Test?
1% para-dimethylaminobenzaldehyde (p-DMBA) dissolved in concentrated HCl in ethylacetate.
What type of reaction is the Ehrlich’s Test?
A Condensation Reaction - water is lost.
What colour change happens when LSD reacts with the Ehrlich’s Reagent?
A Blue/ Purple/ Pink Tertiary Carbocation is formed.
How does the Mechanism work in the Ehrlich’s Test?
The LSD molecule reacts with p-DMBA to form a carbinole which undergoes a condensation reaction to form an unstable secondary carbocation. A proton is added and further LSD molecules to form a Stable Tertiary Carbocation.
What Reagents are used in the Libermann’s Test?
A solution of potassium/ sodium nitrate dissolved in concentrated sulphuric acid.
What colour change happens when a molecule containing a phenol/ amine group reacts with the Libermann’s Reagent?
- Red coloured Quinone imine (Acidic Conditions).
- Blue coloured Quinone imine (Basic Conditions).
Quinone imine - Electrophile (accept electrons).
How does the Mechanism work in the Libermann’s Test?
A Phenol group reacts with the potassium/ sodium nitrate and sulphuric acid to make a Nitroso Phenol. More Phenol molecules are reacted with Sulphuric Acid to form a coupled intermediate. This loses water to form the product based on acidic or basic conditions.
What Reagents are used in the Duquenois-Levine Test?
The Sequential addition of:
1) 2% vanillin and 1% acetaldehyde in ethanol.
2) Concentrated HCl.
3) Chloroform (non-polar).
What colour change happens when THC reacts with the Duquenois-Levine Reagents?
Goes from Colourless/Yellow to Purple/blue colour from the addtion of No.1 to No.2. Finally, a purple coloured chromophore is formed.
Chromophore - a molecule that absorbs light of a specific wavelength and reflects color, making it a colored molecule.
How does the Mechanism work in the Duquenois-Levine Test?
THC undergoes an adol
condensation reaction followed by an electrophilic aromatic substitution resulting in the proposed chromophore structure.
What Reagents are used in the Cobalt Thiocyanate Test?
2% Cobalt Thiocyanate Solution dissolved in conctrated HCl.
What colour change happens when Cocaine reacts with the Cobalt Thiocyanate Reagent?
A Blue Coloured Ion Pair is formed.
How does the Mechanism work in the Cobalt Thiocyanate Test?
When Cocaine comes into contact with HCl it immediately ionises to form the cocaine cation which reacts with the cobalt thiocyanate to form the blue coloured ion pair.
What Reagents are used in the Dilli-Koppanyi Test?
Sequential addition of:
1) 1% cobalt acetate in methanol.
2) 5% isopropylamine in methanol.
What colour change happens when Barbiturates reacts with the Dilli-Koppanyi Reagent?
A violet-blue coloured transition metal complex is formed.
How does the Mechanism work in the Dilli-Koppanyi Test?
When the reagents are added, each of the reactants bond to the same Cobalt atom to form a dative transition metal complex formed of barbiturate molecules opposite each other and isopropalamine molecules opposite each other.
What Reagents are used in the Simon Test?
- 2% Nitroprusside solution containing Acetaldehyde - detection of Methamphetamine.
- 2% Nitroprusside solution in Acetone - detection of Amphetamine.
What colour change happens when Methamphetamine reacts with the Simon Test Reagent?
A Blue Simon-Awe Complex is formed.
What colour change happens when Amphetamine reacts with the Simon Test Reagent?
A Purple Complex is formed.
How does the Mechanism work in the Simon Test?
A (Meth)Amphetamine molecule reacts with the (acetaldehyde/acetone) and loses water to form an Enamine. This then reacts with the Nitroprusside to form an Ammonium Salt and then water is lost to form the Simon-Awe Complex.
- Acetaldehyde reacts with Methamphetamine.
- Acetone reacts with Amphetamine.
Which is the only Colour Test to produce Azo Dyes?
The Fast Blue BB Salt Test.
What Reagents are used in the Fast Blue BB Salt Test?
Fast Blue BB Salt Solution.
What colour change happens when THC reacts with the Fast Blue BB Salt Reagent?
A Red Azo Dye is produced.
What colour change happens when Cannabinol reacts with the Fast Blue BB Salt Reagent?
A Purple Azo Dye is produced.
What colour change happens when Cannabidol reacts with the Fast Blue BB Salt Reagent?
An Orange Azo Dye is produced.
How does the Mechanism work in the Fast Blue BB Salt Test?
Its due to the coupling reaction between the diazonium group of the fast blue bb salts and the activating group (-OH) of phenolic compounds such as THC, CNB and CND.
- CNB - Cannabinol.
- CND - Cannabidol.
What Drug is known to always come in a ‘Plant Matter’ form?
Cannabis.
What Drugs are known to come in a ‘Resin’ form?
Cannabis or Heroin.
What Drug is known to come as ‘Microdots, gelatin squares or blotter papers’?
LSD.
What Drugs are known to come in a ‘White Powder’ form?
Heroin or Cocaine.
What Drugs are known to come in a ‘Tan Powder’ form?
Heroin or Amphetamine.
What are Tan Powders also known as?
Street Drugs (cut with adulterants such as Caffeine or Bleach).
How do you perform a Routine Colour Test?
- A small amount of the suspected drug substance is placed into the tile of a spotting plate.
- A few drops of reagent are added and the IMMEDIATE colour change is noted down.
- A Negative Control Test is performed.
- A Positive Control Test is performed to Tentatively identify the drug.
How do you complete a Negative Control Test?
A drop of reagent is added into a spotting well with no substance, and it is a Negative result if the colour doesn’t change. If it changes colour, then there is possibility of contamination, therefore analysis has to be done all over again.
How do you complete a Positive Control Test?
Standard reference material (e.g. the drug comparing to from ‘the bank’) is added to a well and the same reagent(s) are added. The immediate colour change is recorded and compared to the unknown.
Same Colour Change = TENTATIVE Identification.
How do you perform a Routine Microcrystalline Test?
- Place the unknown drug onto a microscope slide.
- Add a few drops of reagent (gold chloride/ bromide or platinum chloride/ bromide).
- Place a Cover Slip on top and analyse under a transmitted light microscope.
What structure of Microcrystal can Cocaine Crystals be described as having?
Sword-like Crystals.
What structure of Microcrystal can Amphetamine Crystals be described as having?
Plant-like Crystals.
What structure of Microcrystal can Mephedrone Crystals be described as having?
Poses/ Flower-like Crystals.
What structure/ shape of Microcrystal can GHB Crystals be described as having?
Rectangular Crystals.
Which one of the 4 microcrystalline drugs is not used in routine drug analysis testing?
GHB (Gamma-hydroxybutyrate/ 4-hydroxybutanoic acid).
What are the 3 possible types of coloured compound/ chromaphore which can be produced by colour tests?
- Azo Dyes.
- Transition Metal Complexes.
- Carbocations.
What type of chemical structure do **Azo Dyes **have?
R-N=N-R.
What charge do Carbocations have?
Positive (+). This makes them very very reactive.
In Transition Metal Complexes, what are the names of the parts surrounding the central transition metal atom?
Ligands.
What things affect the colour of a transition metal complex?
- Type of Transition Metal.
- Oxidation State(s).
- Type of Ligands.
What is the order of stability for Carbocations?
MOST STABLE
1. Tertiary (3°) Carbocations (3 organic Groups).
2. Secondary (2°) Carbocations (2 organic groups).
3. Primary (1°) Carbocations (1 organic group).
LEAST STABLE
What is a Chromaphore?
Substances which absorb and emit light in the visible region of the electromagnetic spectrum.
In terms of Molecular Orbitals, what does GS and ES mean?
What are they joined in the middle by?
- GS = Ground State.
- ES = Excited State.
They are joined by an ‘energy gap’ in the middle.
What are the differences between the Ground State and the Excited State?
- The Ground State is the lowest energy (ΔE) and only contains bonding orbitals.
- The Excited State is the highest energy (ΔE) and only contains anti-bonding orbitals.
What type of bonding orbitals are associated with single bonds?
Sigma (σ) orbitals.
What type of bonding orbitals are associated with double and triple bonds?
Pi (π) orbitals.
What type of bonding orbitals are not associated with bonding?
n orbitals.
What type of bonding orbitals are found in the Ground State?
Sigma (σ) bonding, Pi (π) bonding and n bonding orbitals.
What type of bonding orbitals are found in the Excited State?
Sigma (σ)* anti-bonding and Pi (π)* anti-bonding orbitals.
How do electrons get transferred from the Ground State to the Excited State?
When electrons are bombarded with light.
How long do electrons stay in the excited state?
A SHORT length of time.
Electrons ____________ photons to get excited to the Excited State and ____________ photons to relax to the ground state.
Photons - light molecules.
- Absorb.
- Emit.
What can you use to determine what colour is emitted when a certain colour of light is absorbed?
The Artists Colour Wheel.
What colour light is Emitted when Orange light is Absorbed?
Blue Light.
What colour light is Emitted when Red light is Absorbed?
Green light.
What colour light is Absorbed when Violet light is Emitted?
Yellow light.
What does the Marquis reagent do to a molecule?
It changes the Structure and Bonding.
The energy required for an electron to be excited is __________ to that energy provided by a photon of __________ light.
- Equal/ Different.
- Colour.
- Equal.
- Blue.
Practice Question:
“When marquis reagent reacts with methamphetamine it produces an orange coloured carbocation. What chemistry is involved to produce this reaction?”
The Marquis reagent causes a change in the structure of the methamphetamine. The electrons absorb photons of blue light to allow them to be excited from the ground state to the excited state and emit photons of orange light (orange carbocation).
Practice Question:
“An unknown powder has been found in the raid of a clandestine laboratory. The police believe that the powder is cocaine. What combination of tests could be undertaken to identify the composition of the white powder.”
Firstly add the Marquis reagent to a sample of the small powder in a spotting well. The colour shouldn’t change. Then do the Cobalt Thiocyanate test to another small sample of the powder. This should produce a blue ion pair as this is the main test for cocaine. You could also do the Mandelin’s test and the Ferric Chloride Test. These are all tentative tests and to confirm the presence of cocaine, you need to analyse with a GC-MS.
