Forensic Toxicology and Chemical Analysis Questions and Answers

Answer: B

Of the tests listed, the one used for amphetamine is the Mandelin test.

The Mandelin reagent (ammonium vanadate in sulphuric acid) gives a green to blue-green colour with amphetamine and methamphetamine. Along with the Marquis reagent, which gives orange to brown, it is one of the colour tests used in screening seized powders for amphetamines.

The other tests are for different drugs: Duquenois-Levine for cannabis, Ehrlich's reagent for LSD and other indoles, and Scott's (cobalt thiocyanate) test for cocaine.

Answer: C

Tactile hallucinations are caused by chronic cocaine poisoning.

Chronic cocaine use produces the characteristic formication, the sensation of insects crawling under the skin, also called Magnan's symptom or cocaine bugs; users may scratch or dig at their skin to remove them.

Cannabis and LSD mainly cause visual and other perceptual distortions, and chronic opium use causes constipation, constricted pupils, emaciation and craving rather than tactile hallucinations.

Answer: B

The key's answer is Tortoise shell. I could not find a published description of hop seeds in these words, so this follows the key.

Hop (Humulus) is a close relative of cannabis: both belong to the family Cannabaceae, so their fruits can look alike, and a seed examiner needs a feature that tells them apart. The key names a tortoise-shell surface as that feature of the hop seed.

The other three terms, endospermic shell, shrivelled shell and hard shell, are not features I could match to the seed-identification literature, so they are eliminated only on the key's reading.

Answer: B

The correct matching is a-iii, b-iv, c-ii, d-i.

• Bhilawanol is the irritant principle of Semecarpus anacardium, the marking nut (iii).
• Hyoscyamine is an alkaloid of Atropa belladonna, deadly nightshade (iv).
• Nerin (oleandrin and neriodorin) is a cardiac glycoside of Nerium oleander, white oleander (ii).
• Calotoxin (printed 'Calatoxin') is a principle of Calotropis gigantea, madar (i).

Only the second code gives (iii), (iv), (ii), (i). These four plants are standard irritant and cardiac poisons in Indian toxicology.

Answer: D

The compound that is not a carbamate is Aldrin.

Aldrin is an organochlorine insecticide of the cyclodiene group, like dieldrin and endrin. Organochlorines act mainly on the nervous system by interfering with sodium channels and GABA receptors and are persistent in the environment.

Aldicarb, propoxur (Baygon) and carbofuran (Furadan) are carbamates. Like organophosphates they inhibit acetylcholinesterase, but the inhibition is reversible, which is why pralidoxime is generally not used in carbamate poisoning while atropine is.

Answer: B

Ganja is obtained from the flowering tops of the cannabis plant.

Of the forms of Cannabis sativa used in India, bhang is made from the dried leaves (and sometimes stems), ganja from the dried flowering tops of the female plant, which are rich in resin, and charas (hashish) from the resin itself. The concentration of THC rises from bhang to ganja to charas.

The NDPS Act, 1985 defines ganja as the flowering or fruiting tops of the cannabis plant, excluding seeds and leaves not accompanied by the tops. Dried or fresh leaves give bhang, and the roots contain little active material.

Answer: C

The octanol/water partition coefficient indicates potential bioaccumulation.

The partition coefficient (Kow, usually given as log P) is the ratio of a chemical's concentration in octanol to that in water at equilibrium. Octanol stands in for body fat and lipid membranes, so a high log P means the chemical is lipophilic: it is absorbed through membranes and tends to be stored in fatty tissue and build up in organisms and food chains. Substances with log Kow above about 3-5 are flagged for bioaccumulation in regulatory screening.

A high Kow may go with a long half-life, but it does not by itself indicate carcinogenicity or toxicity, which depend on the chemical's biological action.

Answer: D

The group not suited for intranasal administration is oleander.

Drugs taken intranasally must be absorbed through the nasal mucosa, which requires them to be fairly potent and lipid-soluble in small amounts. Opioids such as heroin are commonly snorted (and naloxone is given by nasal spray), nicotine is used as a nasal spray in smoking cessation, and cannabis preparations can be taken this way. They are all drugs of abuse or therapy with intranasal routes.

Oleander is a poisonous plant whose cardiac glycosides cause poisoning when the plant is eaten or its extract is given by mouth. It is a poison, not a drug group used intranasally.

Answer: C

SWGDRUG is an international committee that sets standards for the analysis of drugs.

The Scientific Working Group for the Analysis of Seized Drugs, formed in 1997 with the support of the US Drug Enforcement Administration and the Office of National Drug Control Policy, brings together forensic chemists from many countries. It publishes recommendations on minimum standards for drug identification, categorising analytical techniques into A (such as mass spectrometry and infrared spectroscopy), B and C according to their discriminating power, and specifying how they must be combined.

It is not a test, not a street drug and not an enforcement agency.

Answer: A

The key traces choline to the seminal vesicles.

Choline in semen is the basis of the Florence test, a preliminary test in which a seminal stain treated with an iodine-potassium iodide solution forms dark brown, rhomboid crystals of choline periodide. The choline is contributed to the ejaculate by the accessory glands, and the key attributes it to the seminal vesicles.

The prostate is the source of acid phosphatase, PSA (P30) and spermine (detected by the Barberio test). The seminiferous tubules (printed 'Seminiferos') produce sperm, and the bulbourethral glands secrete pre-ejaculatory mucus.