Statistics for forensic toxicology - analytical techniques - hair analysis

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Hint	Answer	% Correct
what are the five basic steps involved in analysis of hair for drugs?	1. sample collection	100%
	2. decontamination	100%
	3. preparation of the hair sample	100%
	4. extraction of the drug molecules	100%
	5. analysis	100%
	absorption via external contamination from the environment (e.g. exhaled cannabis)	100%
	allows flexibility in the timing of sampling because the average segment of 4cm of hair is approximately 3 months (based on average hair growth)	100%
	analytical procedures are well-established for common drugs (analysis can be automated & is cheap)	100%
	barbiturates, benzodiazepines, anabolic steroids, industrial toxins (organic not metals)	100%
blood supply	binding of the drug to keratin (sulphydryl groups)	100%
how can incorporation of the drug into the hair by augmented?	binding of the drug to melanin (hair colour)	100%
what is the main ways drugs or metabolites are incorporated into the hair?	blood supply (endogenous source): ingested drug -> blood -> hair root -> hair shaft (via passive diffusion)	100%
	cannot identify alcohol abuse	100%
	cannot provide a profile of drug use in the 6-7 days immediately after ingestion	100%
	cocaine, amphetamine, nicotine	100%
what do each of these steps involve?	collecting the hair from the head	100%
	collection of samples is non-invasive	100%
blood supply	concentration gradient (blood:hair:root)	100%
	consumption of large volumes of water may dilute urine & avoid detection	100%
	cosmetic treatment of hair can influence drug entrapment	100%
	drug concentrations in spot samples cannot be related to intensity of drug use (cannot distinguish between light, moderate, or heavy use)	100%
	drugs are highly stable when incorporated into hair, therefore giving samples a long shelf life	100%
	environmental contamination can influence results (e.g. exhaled cannabis)	100%
	hair can be matched to individuals using appearance & microscopic examination	100%
	hair colour results in variation of the uptake of certain drugs into hair (based on binding preferences)	100%
	higher capture rate of drugs than urine analysis	100%
5	immunoassays or GC-MS	100%
what are the advantages of hair analysis?	it has the widest surveillance window of any biological matrix (days to years) & segmental analysis can give longitudinal profile of drug use	100%
	it is more expensive then urine analysis	100%
	it is no more effective than urine at measuring cannabis consumption	100%
	it is not possible to adulterate or dilute the sample	100%
blood supply	lipid solubility of the drug	100%
what does the extent of incorporation depend on?	molecular size & structure of the drug	100%
what are the advantages of urine analysis?	most drugs or metabolites of drugs are excreted into the urine at high concentrations (detection is indicative of recent exposure (1-3 days))	100%
what are some drugs commonly analysed in hair?	opiates (heroin, morphine, codeine), PCP, cannabis	100%
	opportunity to collect a second sample in disputed cases	100%
3	pulverisation or segmentation of the hair	100%
blood supply	ratio of ionised;unionised forms of the drug (pKa of the drug)	100%
what are the disadvantages of urine analysis?	samples can be tampered with (adulterated, substituted, or diluted, & collection requires strict supervision)	100%
	sampling is non-invasive	100%
	surveillance window is short (1-3 days), meaning infrequent use is not detected by random testing & screening can be delayed to avoid detection	100%
what are some other ways drugs or metabolites can be incorporated into the hair?	sweat (exogenous source): excreted drug -> sweat in scalp -> hair (via absorption)	100%
	there is a lack of international standardisation for both analytical & interpretation criteria (particularly in washing & extraction methodologies)	100%
	urine is not a complex matrix, so sample preparation is minimal	100%
	using hair analysis is court is difficult because of lack of standardisation, lack of agreement on methodology, contamination, the effect of hair treatments, and differences between ethnic groups	100%
4	using organic solvents or acids or alkali based extractions	100%
what are the disadvantages of hair analysis?	variation in growth rate can be problematic	100%
	washing the hair to remove external contamination is highly variable in its effectiveness	100%
2	washing the hair using a phosphate buffer, detergent (including shampoo), or surfactants	100%