9 - Hair Analysis in Forensic Toxicology Flashcards
1
Q
Give two uses of hair analysis
presumptive and confirmatory
A
- Match hair to suspect - microscope
- Confirm drug consumption - GC/MS
2
Q
Explain the structure of hair
A
- Hair follicle & sebaceous gland in pilosebaceous unit
- Pilosebaceous unit where hair synthesis, growth, keratin and melanin are
- Hair made of 65-95% keratin, 15-35% water, 1-9% lipids, >1% minerals
- Cortex - hair fibre core, melanin found here
- High eumelanin = black hair, low eumelanin = blonde, pheomelanin = red
3
Q
How is the medulla in a) Caucasian hair, b) African hair, c) Asian hair?
A
a) fragmented/absent
b) fragmented/absent
c) continuous
4
Q
Explain a few of the theories of how drugs enter the hair
A
- passive diffusion from capillaries around hair into hair
- drug in sebaceous gland, enters hair during hair growth
- drug binds to hair from sweat & sebum
- melanin responsible for hair colour so could cause drugs to bind from here
5
Q
What is the benefit to having darker hair over lighter hair?
A
Darker hair retains more drugs
6
Q
What is the benefit of hair analysis in the case of a drugging?
A
Can corroborate victims time of drugging
7
Q
When is hair analysis useful?
A
- post-mortem toxicology
- child custody cases
- drug facilitated crime
- workplace drug testing
- doping
8
Q
How is hair sampled for hair analysis?
A
- pencil thickness
- taken from posterior vortex (least growth rate variability)
- stored in foil fold inside of envelope
- minimum 2 inches long
9
Q
How is hair prepared for analysis?
A
- decontaminated (contaminated cosmetics)
- segmented & pulverised - increase SA, internal content can be accessed
- digestion - make drug lipid soluble
extraction - LLE/SPE - identify - GC/MS, LC/MS, LC-MS/MS
10
Q
What factors affect a hair sample?
A
- hair structure damaged - heat, light, cosmetics, causes irregular movement and incorporation of drug
- drug degradation - photosensitive drugs in UV light (sun)
- bleached/dyed hair - more porous, loss of drug
- pharmacokinetics different per individual - cannot determine dosage/quantity administered
11
Q
Three advantages of using hair as a matrice
A
+ hard to adulterate
+ non-invasive
+ history of drug use
