Drug Analysis Flashcards
How do drug cheats get away with it?
- Using new drugs and chemical variants
- Masking drugs use with non-banned substances
- Dilution of sample by taking diuretics before testing
- Adulteration of sample to change the chemistry
What are the key pieces of information in forensic drug investigations?
- identification
- quantification
- provenance/origin
Identification
- both preliminary identification of a suspected drug and full identification of mixtures
Quantification
- how much of the active and other chemical species are present in the sample
- blood testing: how much of a drug or its derivative are in a sample
Provenance/origin
- where the drug is from
- geographically, as well as chemically (starting materials used)
What are types of drug related samples?
- solid and liquid samples of preliminary identified illicit drugs
- chemical residue on clothing and equipment
- suspected counterfeit or illegal pharamaceutical drugs
- blood and urine analysis
- hair samples
- saliva samples
What are impurities useful for?
- identify likely starting materials used for drug synthesis
- chemically link samples and evidence
- ‘fingerprint’ for identifying the origin of a sample
What are the tests used for preliminary identification?
- colour change preliminary drug identification
- alcohol breath tests
- roadside cannabis and amphetamine tests
What are the advantages of HPLC? (5)
- a wide range of samples can be examined
- good separation and low detection limits
- 15-30 minutes
- results are quantitative, reproducible and precise (high degree of confidence)
- can be non destructive as mixture fractions can be recovered
What are the advantages of GC? (6)
- very complex mixtures can be separated
- qualitative and quantitative
- very low detection limits (ppt)
- results are precise and reproducible (high degree of confidence)
- rapid results (1-60 minutes)
- very small sample volume required
What are the disadvantages of HPLC? (3)
- expensive due to large amount of solvent required and short column life
- some chemicals can not pass through the column as they get ‘stuck”
- high levels of technical expertise required to rim and process samples with confidence
What are the disadvantages of GC? (6)
- sample must be volatile and heat stable
- heat sensitive species must first be converted chemically
- often require a significant amount of sample preparation
- no solids can pass through the instrument
- often dilution is required of a sample to not overload the system
- water is not a suitable solvent and thus samples often have to be converted
How is qualitative analysis achieved in chromatography?
- reference materials that have been processed using the same method as the sample can be used to positively identify the presence of the target substance in the sample
- this is done by matching retention times
How is quantitative analysis achieved in chromatography?
- achieved by inter grating the area under the peaks to obtain a value for peak area
- the relative amount of a compound can be determined by relating the area to a calibration curve that is made using different amounts of the reference material
Which method is used for testing BAC?
Specialised GC
How are drugs analysed?
HPLC and GC
What can HPLC and GC tell about drugs?
- purity of the key illicit or counterfeit chemical compounds
- identify and quantity impurities and cutting agents
What is produced to show results in chromatography?
Chromatogram
What is the process of gas chromatography?
- A very long glass column (30-50m) is coated on the inside with a very thin layer of sticky, polar liquid - stationary phase
- The sample is introduced as a gas to a non-polar carrier gas - mobile phase
- Mixture is then passed through the column
- The more polar molecules take more time to pass through the column because they have a greater affinity for the stationary phase, the less polar molecules take less time because they interact with the mobile phase
How does HPLC work?
- similar in concept to GC except a liquid mobile phase and a solid stationary phase are used
- in HPLC the column is much shorter and wider
What do the 2 most common synthetic route of the synthesis of methamphetamines use?
- 1-phenyl-2-propanone (P2P)
2. Ephedrine or pseudosphedrine
