Drug detection Flashcards
Why do we need to have methods for detecting drugs?
Treatment
Safety
Anti-doping measures
Law enforcement
Research
What kind of biological samples can be taken
Blood
Breath
Urine
Saliva
Hair
sometimes a particular method may be preferable over another because it isn’t sensitive enough to detect lower
amounts of a drug
What to measure
Identification - screening
Measure levels
Known vs unknown
Alcohol detection- chemical colour change
Breathalyzer
0.08% BAC (estimated)
Chemical colour test with sulphuric acid, silver nitrate and potassium dichromate
Colour change – electric current in meter
combination of chemicals react with alcohol in breath changing electric current in meter
calibrated to reflect level of alcohol in blood
very portable- good for motorway, estimates level of alcohol
but disadvantage- prone to error, can be second detection using infrared spec- a blood test. this is more accurate but by the time sample is taken a lot of alcohol could have been metabolised but you could then solve that by looking for metabolites
alcohol detection- IR
Intoxilyzer – infrared spectroscopy
IR beam in wavelengths for chemical bonds in ethanol
IR absorption – electrical signal
breathalysers measure alcohol- possible because its a volatile chemical, it comes out in your breath
colour test
Solid tests- what they’re used for+ advantages and disadvantages
Immunoassays Cocaine Ketamine THC Methamphetamine Benzodiazepines
ease of use- then won’t need specially trained scientists
breathalyser doesnt need much training
solid tests are even more user friendly- like the pregnancy test, does not require expertise
has antibodies or immunoassays- sample attracts antibodies and travels through capillary action
tells you specificity
it’s a good QUALITIATVE tester- so will tell you if you have cocaine or not + gives detection threshold
but disadvantage is doesn’t give you exact concentration (might be useful medically)
Simple
Rapid
Visual interpretation
On-site detection
Kit completes with swab for sample collection, buffer solutions, bottle for mixing compound and test cartridge
Some have Home office approval – police, customs
Sensitivity ? Detection times ?
Urine test strips
Allow the test to absorb the urine for about 10-15 seconds.
- Remove the test from the urine and replace the test cap.
- Lay the test on a clean flat surface while the test lines develop.
- You can read negative results as soon as they appear but positive results must be read at least 5 minutes after removing from urine.
drug on stick, absorbed and moves on strip by capillary action
However, what makes a positive/negative test?
What is being detected ?
What is the detection limit ?
When was the drug taken (and how much) ?
How to confirm the initial tests ?
you want to have reasonable sensitivity
unless you deliberately only want to catch with very high abuse
Home testing kits
Marguis reagent: 1% formic acid in concentrated sulphuric acid
MDMA
Methamphetamine
Morphine
people started buying tests to see if a pill was pure ecstatsy or really the actual pill
you can use some drugs in powered form, dissolve in acid reagent, cause a colour change, match colour to a colour chart/colorimetry
reagents that can be used for home qualitative tests
PMA: 4-methoxyamphetamine
PMA doesn’t show up in chemical s in tablets
so it’s more of a qualitative test
Mandelin reagent: ammonium vanadate in concentrated sulphuric acid
Mecke reagent: selenous acid in in concentrated sulphuric acid
qualitative” test
What was the ACMD report on powdered cocaine (2015)
Increased availability of cheap, low purity powdered cocaine
Cocaine (including crack) was involved in, but not necessarily the cause of, 234 of 3,521deaths in England, Scotland and Wales in 2013
More than 50 cutting agents have been identified, including some that can cause serious medical harm
Gas chromatography mass spectroscopy
Laboratory test
Reliable
Sensitive
Screening of substances
Quantitative
this is quantitative
but requires trained people to use
Infrared spectroscopy
Unambiguous identification
Reliable
Rapid
Extensive drug library needed inc IR spectra of legal highs, pharmaceutical compounds and common chemicals
No sample preparation
Portable – use outside laboratories ?
IF gives you the convenience of the home kit tests
and the reliability of the mass spec
Why do we have drug databases
It’s important to detect emerging drugs that may be harmful
important to have database of infrared spectra in order to be able to easily match up to already identified compounds
same drug sometimes exists in different forms eg crack can be powdered or crystal form
drug databases can be built up
drugs can have the same pharmacological effects but different pharmacokinetic effects
How to keep up with markers and users
There is an ongoing cycle between a blanket ban, new emerging drugs/substances invented, detection and back to blanket ban
Designer drugs: modified structures of existing substances
Failed pharmaceuticals or research compounds
Each country is different
EMCDDA, UNODC
European Monitoring Centre for Drugs and Drug Addiction (EMCDDA)
United nations office on drug and crime (UNODC)
these help to keep up with new drugs- people might alter structure of drugs so that they are not illegall anymore, but these drugs can still have the same harmful pharmacological impacts (can be toxic) very high risk
so its important to have these databases to keep up with designer drugs and the law can be updated as well
so government decided to have blanket ban on ANY pyshoactive substance
but even things like coffee are psychoactive- makes you more alert?
creation of new psyhchoactive substnaces hasn’t stopped completely and there is a tendency for the substances to be more potent than they were before modification
Detective work to find new emerging drugs
Internet / headshops Systematic screening for new compounds Monitor effects of new legislations Amnesty bins from clubs or festivals Search before entry, anything left in sealed container
Police and Border Agency
Drug testing following arrest
Seizures (inc. unclaimed parcels)
Hospital admissions
sometime you can scan for emerging drugs
use biological and drug samples to pinpoint drugs of abuse in a and e in hospital admissions
Questionnaires (brand names only)
Waste
Pooled urine (no female samples)
Sewage
these are from open urinals
can compare countries and emerging drugs detected
if you do a longitudinal study over a long period of time and compare with a policy change
use a combo of thecniques eg use a questionairre and the end product of drugs in urinals to test population’s awareness on what they’re taking?
