Drug analysis in Forensic Science

define forensic science?

•       Forensic – used in connection with courts of law.

•       Forensic Science: science applied to legal problems.

•       3 important areas,

•    Forensic chemistry.

•    Forensic toxicology.

•    Forensic biology.

Forensic chemistry, drugs

•       Drug analysis 80-90% of work,

  

o   Illicit substances eg. cocaine, LSD, heroin, cannabis.

o   Licit substances abused – benzodiazepines, opiates.

o   Pharmaceuticals.

 

forensic chemistry?

•       Fire Investigation.

•       Physical evidence,

• o   Glass comparison by refractive index.

• o   paint comparisons by infrared spectroscopy.

•       Unknown chemical analysis,

• o   Analysis of pepper or CS sprays (identify as firearm).

• o   Vandalism.

forensic toxicology?

•       Involves analysis of drugs and poisons in biological specimens,

•    Blood, urine.

•    Liver, bile, stomach contents.

•    Vitreous humour/

•    Hair, saliva.

•       Requires a knowledge of analytical chemistry, pharmacology.

forensic biology?

•       Blood spatter analysis.

•       DNA.

•       Hair/fibre analysis.

•       Links with other areas including,

•    Odontology.

•    Anthropology.

•    Entomology.

drug legislation?

•       Misuse of Drugs Act 1971:

•       https://www.legislation.gov.uk/ukpga/1971/38/contents

•       Updates to an act are known as a Statutory Instrument (SI).

misuse of drugs regulations 2001

https://www.legislation.gov.uk/uksi/2001/3998/contents/made

 

Important Points

•       Definitions.

•       Schedules 1-5 (Regulations), Classes (Act).

•       Generic controls.

 

psychoactive substances Act 2016

https://www.legislation.gov.uk/ukpga/2016/2/contents

forensic chemistry: abused drugs

•       Typically, a seized material is brought to forensic laboratory,

o   Follows chain of custody.

•       Packaged securely at scene.

•       Transported to laboratory.

•       Logged at lab reception and stored.

•       Analysis carried out.

forensic chemistry: sources of information

•       United Nations Office of Drugs and Crime (UNODC),  www.unodc.org

•    Detailed methods for drug analysis, online manuals.

•    World drugs report – statistics, trends.

•       US Drug Enforcement Agency,  https://www.dea.gov/law-enforcement/forensic-sciences

•    Microgram bulletin.

•    International narcotics Control Board, www.incb.org

laboratory procedure

•       Detailed notes at every stage.

•       Mistakes- score once and initial.

•       Examination:

1.    Security of packaging,

•   Is packaging secure.

•   Tampered – reject/note.

2.    Description of contents.

3.    Weights.

drug identification?

•       Normally 3 separate parameters are required,

o    2 chromatographic,

•   Gas chromatography (GC).

•   High performance liquid chromatography (HPLC).

•   Thin layer chromatography (TLC).

o    Mass Spectrometry (MS).

•       For example,

o   GCMS (2 parameters).

o   HPLC (1 parameter).

identification continued:

•       Pharmaceuticals – size, shape, colour and manufacturers mark.

•       Unknowns – rule out controlled drugs.

•       Colour tests are carried out,

•    Not a parameter.

•    Guide for subsequent analysis.

•    Exception – cannabis.

pharmaceutical preparations, legislation?

TICTAC drug identification:

https://www.tictac.org.uk/

Illicit Pharmaceuticals?

•       Many pharmaceuticals are copied and available on black market,

•    No guarantee of strength.

•    Other compounds added.

commonly used colour test?

Reagent	Compounds
Van Urk Reagent	Indole alkaloids: LSD and Psilocin: grey/violet.
Modified Scott	Cocaine: blue/pink
Duquenois - Levine Reagent	Cannabis products

marquis reagent ?

Most commonly used reagent is Marquis reagent.

Mixture of conc. H₂SO₄ and formaldehyde.

Colour Change	Drug Substance
Orange	Amphetamines
Blue-black	Ring substituted amphetamines
Shades of purple	opiates

drug substances, Heroin?

• Latex sap of opium poppy (Papaver somniferum),

• Raw opium.

• Average constituents.

Alkaloid	%
Morphine	11.4
Codeine	3.5
Thebaine	3.1
Papaverine	3.2
Noscapine	8.1

product of Heroin?

-              Extraction of morphine from opium as HCl salt.

-              Structurally related compounds also extracted.

-              Acetylation using acetic anhydride.

structurally related compounds?

-              Other compounds may also be acetylated for example codeine.

-              Partial acetylation is also possible at 3- and 6- positions of morphine.

-              Thebaine, noscapine and papaverine are not acetylated.

commonly used analytical techniques?

•       Gas Chromatography (GC),

•   Detectors include FID (flame Ionisation detection), NPD (nitrogen phosphorus detector), ECD (electron capture detector).

•    Mass spectrometry (i.e. GCMS).

•       HPLC high performance liquid chromatography,

•   Detectors include UV (ultraviolet), fluorescence, electrochemical.

•    Mass spectrometry (i.e LCMS).

Gas Chromatography – Mass Spectrometry (GCMS) Analysis?

GCMS diagram?

GCMA : Heroin

GCMS heroin components:

Cannabis, Sativa plant has provided a source of:

•       Cannabis Sativa plant has provided a source of:

o   Fuel.

o   Textiles.

o   Paper.

o   Rope.

o   Medicines.

o   Intoxication.

definition, Misuse of drugs act?

cannabis form?

•       Cannabis refers to the plant,

o   Skunk: strains bred for higher content of main active ingredient (THC).

•       Controlled under drug law,

o   Leaf.

o   Flowering tops.

•       Often not controlled,

o   Seeds.

o   Stalk.

1. form of cannabis: Resin?

•       Collection of resin,

•   Brush past plants with rubber sheets.

•    Scrape resin from sheets.

•       Blocks of compressed resin,

•    Typically wrapped in plastic.

•    Logos.

•    Approx. 250g (±10g).

•    Divided using hot knife.

2. form of cannabis: oil?

•       Solvent extract of:

o   Cannabis.

o   Cannabis resin.

o   Concentrated.

Form	% Main active component THC
Cannabis	1-3
Cannabis resin	4-9
Cannabis oil	= 20-50

constituents of cannabis?

•       Cannabinoids – active constituent of cannabis.

•       ›300 compounds,

o   Approx. 60 potentially active,

•         5 numbering systems – 2 are commonly used.

Constituents: ∆-9-Tetrahydrocannabinol

•       ∆-9-THC, or THC,

o   Dibenzopyran system.

•       ∆-1-THC,

o   Monoterpene system.

•       Main active ingredient in cannabis.

other important constiuents?

laboratory analysis of Cannabis?

•       3 parameters for identification,

o   Chemical colour test.

o   Thin layer chromatography.

o   Microscopy.

•       All of these tests are carried out on cannabis, cannabis resin and oil.

•       Some labs carry out GCMS.

Problems with fresh cannabis	solution
Chlorophyll masks colour test.	Dry sample in oven and repeat.
Packaged in plastic – mould can cause asthma.	Package in paper (breathable) carry out analysis in fume hood.

chemical colour test?

•       Duquenois - Levine Test.

•       Shavings (using scalpel) are added to test tube.

•       Add 5 drops of Duquenois – Levine reagent (vanillin/acetaldehyde/ethanol)

•    and equal volume of conc. HCl.

•       Purple colour within 2 minutes.

•       Add CHCl₃ and shake.

•       Both layers should be purple.

interferences - colour test?

•       Tea – purple colour, but no coloured chloroform layer.

•       Nutmeg – murky blue colour, lilac coloured chloroform, only after standing for at least 30 minutes.

•       Some herbs and spices.

•       Generally other parameters will also rule these out.

thin layer chromatography?

•       2 or 3 drops of petroleum ether added to sample – extracts non-polar cannabinoids.

•       THC, CBN, CBD spotted to plate.

•       Toluene used as developing solvent.

•       Plates dried and sprayed with fast blue RR salt or fast blue B salt solutions.

•       Highly coloured bands.

•       Measure Rf’s.

microscopy?

•       Shavings of sample placed on microscope slide.

•       Add drops of chloral hydrate.

•       Place cover slip.

•       Heat gently over spirit burner, moving cover slip.

•       Remove from heat and exam at magnification 10-50X.

•       3 main features:

1. o   Cystolithic trichomes (CT).

2. o   Non cystolithic trichomes (NCT).

3. o   Multicellular glandular trichomes (MCGT).

features?

•       5,14,3 stages of multicellular glandular trichomes.

•       6,7 cystolithic trichomes.

•       9,11 non cystolithic trichomes.

lab analysis: interpretation?

It is vital that the scientist can distinguish between the three types below:

Cannabis Resin	Cannabis	Active Principles
Characteristic appearance of resin.	Appearance of plant substance	Too small to see or badly charred
+ ve Duquenois	+ ve Duquenois	+ ve Duquenois
3 botanical features (CT, NCT, MCGT)	2 botanical features (CT, NCT) MCGT as 3rd if mature plant	Botanical features absent or badly charred
TLC: 3 standards shown (THC, CBN, CBD)	TLC: at least THC	TLC: 3 standards shown

stimulants: phenethylamine derivatives?

•       Broadly subdivided,

o   Amphetamine type,

•   Stimulant properties.

o   Ring substituted amphetamine type,

•   Stimulant properties.

•   Hallucinogenic from side chain.

examples?

Typical forms of Amphetamine type stimulants?

chemical analysis?

•       Colour test : Marquis reagent,

o   Orange : amphetamines.

o   Blue black : ring substituted.

•       GCMS analysis,

o   Compounds have polar groups and do not chromatograph well.

o   Small molecules M/Z ions not specific.

•       Therefore, chemical derivatisation is carried out.

chemical derivatisation?

•       Decreases polarity on active hydrogen atoms (OH, NH, SH).

•       Improves chromatography.

•       May improve stability/detectability.

•       Creates more distinguishable ions.

•       Commonly,

o   Sialylation (addition of –Si (CH₃)₃).

o   Acetylation.

o   Acylation (addition of alkyl group e.g. CH₃).

 

Example: Acetylation of Methamphetamine:

MS Spectra of Derivatised Morphine:

example package, sent to Cherie Blair?

•       Former UK prime minister’s wife.

•       Package posted,

o   Consisted of bottle with commercial label, Eucalyptus oil.

o   Typed instructions : rub on face.

o   Intercepted at Downing Street sorting office as suspicious.

•       Wooden board (backing of wardrobe) found in accused’s house with white staining.

Laboratory examination?

•       Bottle contained white slurry,

o   Slippery feel between finger of glove.

•       High pH in solution (14).

•       Flame test yellow,

o   AAS confirmed high levels of Na.

•       Thought to be NaOH.

•       Analysis of white staining on board revealed similar results.

•       Conclusion: although analysis was not totally exhaustive – gave police a lever in terms of gaining an admission from accused.

accused?

•       2 schoolboys.

•       Other letters had been posted containing,

o   Powders.

o   Notes suggesting anthrax spores.

•       One notable recipient Prince William,

o   Studying at St Andrews University at the time.

•       Schoolboys admitted charges,

o   Blamed unknown internet anarchist for ideas.