Exam aid · Exam-specific: DRAP and PFSA

Forensic Toxicology & Narcotics

Colour tests, markers, specimens and poisons for the PFSA toxicology and narcotics paper, on one page.

Practise Toxicology MCQs

Tables to memorise

Cover the right-hand column and test yourself before checking.

Presumptive colour tests

ReagentPositive for (colour)
MarquisOpiates (purple); amphetamines (orange-brown)
MeckeOpiates (green–blue)
Duquenois–LevineCannabis (purple, into chloroform)
Cobalt thiocyanate (Scott)Cocaine (blue)
Simon'sSecondary amines, e.g. methamphetamine (blue)
Ehrlich (p-DMAB)LSD, indoles (purple)
Dille–KoppanyiBarbiturates (violet)
Silver nitrate paperPhosphine from aluminium phosphide (black)
Sodium dithioniteParaquat (blue)

Markers and metabolites

MarkerIndicates
6-MAMHeroin
BenzoylecgonineCocaine
CocaethyleneCocaine + alcohol
THC-COOHCannabis
EtGAlcohol
COHbCarbon monoxide
Low RBC cholinesteraseOrganophosphates

Specimens

SpecimenUse
Femoral bloodPost-mortem quantitation
Heart bloodInflated by redistribution
Vitreous humourAlcohol, electrolytes, decomposed bodies
UrineScreening; exposure not impairment
HairMonths of history
Blood for alcoholSodium fluoride + oxalate

Law and control

ItemFact
CNSA 1997Pakistan's narcotics, psychotropics and precursors law
ANFFederal narcotics enforcement agency
1961 ConventionNarcotic drugs
1971 ConventionPsychotropic substances
1988 ConventionTrafficking and precursors (acetic anhydride, ephedrine)
INCBMonitors the conventions (Vienna)
ISO/IEC 17025Accreditation standard for forensic labs

One-liners examiners love

  • Heroin = diacetylmorphine; codeine = methylmorphine.
  • Charas = resin, bhang = leaves, ganja = flowering tops.
  • Every presumptive positive needs GC-MS or LC-MS/MS confirmation.
  • Poppy seeds give morphine and codeine but never 6-MAM.
  • Post-mortem ethanol can be produced by microbes: check vitreous.
  • GC-MS spectra are acquired at 70 eV so they match library spectra.

Memory aids

Marquis Morphine Mauve; Scott Spots Snow; Simon's Secondary
Marquis = opiates purple; Scott = cocaine blue; Simon's = methamphetamine blue.
Femoral for Facts
Quantify post-mortem drugs in femoral, not heart, blood.

Now turn it into marks

Attempt MCQs on these topics while the sheet is fresh. Anything you get wrong goes to your incorrect list for the next round.

Most useful for

More cheat sheets