Drug Analysis Flashcards
1
Q
How do drug cheats get away with it?
A
- 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
2
Q
What are the key pieces of information in forensic drug investigations?
A
- identification
- quantification
- provenance/origin
3
Q
Identification
A
- both preliminary identification of a suspected drug and full identification of mixtures
4
Q
Quantification
A
- 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
5
Q
Provenance/origin
A
- where the drug is from
- geographically, as well as chemically (starting materials used)
6
Q
What are types of drug related samples?
A
- 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
7
Q
What are impurities useful for?
A
- identify likely starting materials used for drug synthesis
- chemically link samples and evidence
- ‘fingerprint’ for identifying the origin of a sample
8
Q
What are the tests used for preliminary identification?
A
- colour change preliminary drug identification
- alcohol breath tests
- roadside cannabis and amphetamine tests
9
Q
What are the advantages of HPLC? (5)
A
- 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
10
Q
What are the advantages of GC? (6)
A
- 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
11
Q
What are the disadvantages of HPLC? (3)
A
- 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
12
Q
What are the disadvantages of GC? (6)
A
- 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
13
Q
How is qualitative analysis achieved in chromatography?
A
- 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
14
Q
How is quantitative analysis achieved in chromatography?
A
- 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
15
Q
Which method is used for testing BAC?
A
Specialised GC
