Forensic Toxicology

Forensic Toxicology Quiz Crafted by-

Dr. Mamta Pal

Former Associate Professor

Department of Forensic Science

School of Basic & Applied Sciences, Galgotias University


Introduction about Toxicology 

Poisons are substances which causes harm to an organism when absorbed, inhaled or ingested in sufficient quantity. A toxin is a poisonous substance that is produced within the living cells. Toxicology is the science that involves the study of chemical substances and their adverse effects on living organisms.

Here’s the short interview of Quiz maker

Can you enlighten us how forensic toxicology is different from toxicology?

Toxicology is the discipline, which deals with the study of substances which can exert adverse effects on the biological system and it encompasses their interaction, symptoms, diagnosis and treatments in living organism. Whereas, in conjunction to the toxicology, Forensic toxicology deals with the analysis of toxic substances by various methods and techniques to aid the legal investigation to know the cause of poisoning, which is referred as the medico-legal aspect of poisoning. Further, forensic toxicology utilizes the other disciplines also such as pharmacology, clinical toxicology and analytical chemistry for the examination of nature and cause of toxicity.

How toxicological analysis is performed?

Toxicological analysis is performed by presumptive colour test followed by crystal test and finally confirmed by analytical instrumental technique and the sample required for such analysis depends upon the type of case, for example, whether the toxicity has reported in live person or it is the case of deceased person or whether a drug or poison has recovered in pure form or has seized in crude form. Thus, if the cause of toxicity is to be established in live person, the sample required would be the blood, urine, vomit content, nails, hairs etc. and if the cause of toxicity is to be determined in a deceased, the analysis will be carried out in bile juice, stomach content, visceral organs such as liver, heart, brain tissue etc. depending on the nature of the poison. Therefore, from the toxicological examination point of view, collection and preservation of biological samples are also of the great importance.

How drugs are identified?

Identification of drug, whether it is found in pure form or in mixture or seized in crude form or recovered from biological exhibits (in case of poisoning in live person or deceased), requires chemicals, reagents, precise methods for sampling to perform presumptive tests and crystal tests followed by instrumental analysis by employing sophisticated techniques such as colorimetry, spectrophotometry, chromatography etc. depending upon the type of poison or drug to be analysed. For e.g., if it is the case of metallic poisons analytical techniques used are AAS, MS, ICP etc. whereas, in case of volatile poisons, GC is used and examination of non-volatile drugs is carryout by LC.

Are there any techniques which can give rapid results?

There are various hyphenated techniques which are employed for the accurate and rapid identification of poisons. When one analytical technique is coupled with the another analytical technique, it is known as hyphenated technique like coupling of chromatographic technique with spectrophotometric technique such as hyphenation of liquid chromatography with mass spectrophotometry is known as LC-MS, hyphenation of gas chromatography with mass spectrophotometry is known as GC-MS and ICP-MS is the example of coupling of emission spectroscopy with mass spectrophotometry etc., which make the analysis more advanced. Where, LC/GC are used to separate the pure analyte from a mixture and MS is used to characterize the purified component and hence, provide rapid, accurate and reproducible results.

Now let’s have a look at the answers of the Quiz:

Ques 1. Corrosive poisons are the poisons which

a)      Affect CNS

b)      Cause paralysis of muscles

c)      Cause inflammation at the site of contact

d)      Multiple organ failure

Answer. (c) cause inflammation at the site of contact

Explanation: Ingestion of corrosive substances may cause severe injuries to the gastrointestinal tract and even death. Corrosive substances such as acids (hydrochloric, acetic, sulfuric, lactic, oxalic, carbolic), alkalis (sodium and potassium, soaps, detergents), heavy metal salts (sublimate), formalin, iodine tincture and many other chemical substances, cause oral intoxication when ingested.

Ques 2. Which one of the following is corrosive acid?

a)      NaOH

b)      KOH

c)      Na2CO3

d)      HCL

Answer. (d) HCL

ExplanationHCL is the aqueous (water-based) solution of hydrogen chloride gas. It is a strong acid and the major component of gastric acid. It is widely used in industries. It should be handled with appropriate safety precautions because it is a highly corrosive liquid.

Ques 3. Chloroform in the biological exhibit is identified by?

a)      TLC

b)      GC

c)      HPLC

d)      AAS

Answer. (b) GC

ExplanationChloroform is a heavy volatile liquid which can be identified using gas chromatography. GC is a separation technique utilized to analyze volatile compounds in gas phase. It was discovered by Mikhail SemenovichTsvett in 1900s.

Ques 4. Which one of the following is known as oil of vitriol?

a)      HCL

b)      H2SO4

c)      HNO3

d)      Linseed oil

Answer. (b) H2SO2

ExplanationOil of vitriol or H2SO2 is a hygroscopic, syrupy corrosive liquid. It is called oil of vitriol because earlier it was prepared by heating green vitriol (iron II sulphate, FeSO4) in an iron container.

Ques 5. Following method is used for the extraction of metallic poisons

a)      Dry ash method

b)      Wet digestion method

c)      Both dry ash and wet digestion method

d)      None

Answer. (c) Both dry ash and wet digestion method

ExplanationThe residue left after performing dry ash method is tested for metallic poisons such as copper, zinc, barium, bismuth, etc. Wet digestion method is also known as acid mineralization which involves chemical decomposition of sample matrices using oxidizing and dehydrating properties of concentrated minerals acids into aqueous solutions.

Ques 6.Reinsch test is used for?

a)      Mercury

b)      Arsenic

c)      Both arsenic and mercury

d)      None

Answer. (c) Both arsenic and mercury

ExplanationAmong heavy metals, arsenic is the second most common cause of poisoning. Contrarily, mercury poisoning is relatively uncommon but still poses threat because of its extreme toxicity. Reinsch test can be used as a screening tool for both arsenic and mercury.

Ques 7.  Stricture formation is more common in the following case?

a)      Neutral poisons

b)      Alkali poisoning

c)      Acid poisoning

d)      None of the above

Answer. (b) Alkali poisoning

ExplanationCaustic ingestion is a serious health issue due to the ready availability of caustic agents. Substances with high pH are very corrosive and can cause severe injury to the gastrointestinal tract. It affects esophagus and stomach most seriously and may lead to chronic complications like stricture formation, gastric outlet obstruction, and malignant transformation.

Ques 8. Metallic species can be identified by?

a)      MS

b)      ICP

c)      AAS

d)      All of the above

Answer. (d) All of the above

ExplanationMS measures mass-to-charge ratio of molecules present in a sample and generates metal specific isotopic spectra, ICP uses emission spectra to identify and quantify an aerosol sample and AAS utilizes element specific light absorption to determine the concentration of a metal in a solution.

Ques 9. Diamond dust is an example of?

a)      Inorganic poisons

b)      Organic poisons

c)      Mechanical poisons

d)      Both a & b

Answer. (c) Mechanical poisons

ExplanationDiamond dust does not act as a poison as it does not get dissolved in blood but it is a mechanical poison as it acts mechanically by causing irritation to the gastrointestinal tract.

Ques 10. Neurotic poisons are the poison which affects?

a)      CNS

b)      Peripheral of brain

c)      Spinal of brain

d)      All of the above

Answer. (d) All of the above

ExplanationNeurotic poisons affects different parts of central nervous system. Cerebral poisons such as alcohol, opium, barbiturates, etc. are CNS depressing agents, Strychnine is a spinal poison which is an active constituent derived from strychnosnux vomica and Curare is a peripheral poison which affects the peripheral nerves of the brain.

Ques 11. Curare is a

a)      Peripheral poison  

b)      Cerebral poison

c)      Spinal poison

d)      Cardiac poison

Answer. (a) Peripheral poison

ExplanationCurare is a neuromuscular blocking agent as it produces flaccidity in muscles. Various tropical American plants are its source.

Ques 12. Strychnosnux vomica is a?

a)      Cardiac poison

b)      Spinal poison

c)      Cerebral poison

d)      Peripheral poison

Answer. (b) Spinal poison

Explanation :The dried seeds of nux-vomica are called Kuchla which contains 2.6%-3% total alkaloids, out of which 1.25%–1.5% is strychnine, 1.7% is brucine and the rest are vomicine and igasurine. It inhibits the inhibitory action of spinal interneurons on the muscles and leads to twitching and muscle spasms.

Ques 13. Following is a cardiac poison

a)      Ethyl alcohol

b)      Strychnine

c)      Dhatura

d)      Digitalis

Answer. (d) Digitalis

ExplanationDigitalis is also known as foxglove. Its leaves are used to extract digoxin, a cardiac glycoside which inhibits Na+/K+ ATPase pump in cardiac muscles indirectly increasing the calcium levels, allowing the heart to work more efficiently. But when given in large amount and more frequently it becomes toxic leading to sickness, giddiness, slow pulse, etc. and even death.

Ques 14. Following is not an example of asphyxiant

a)      CO

b)      O2

c)      CO2

d)      CH3

Answer. (b) O2

ExplanationOxygen is a tasteless, odorless and colorless gas which supports life. It is non-combustible but supports burning of combustible substances.

Ques 15. Following are the category of agricultural poisons

a)      Organochloro insecticide

b)      Organophosphorous insecticides

c)      Carbamates

d)      All of the above

Answer. (d) All of the above

ExplanationAgricultural chemicals are pesticides that includes insecticides which is divides into four main categories, which are: organophosphates, carbamates, chlorinated hydrocarbons and insecticides. Organophosphates and carbamates exaggerate the normal functions of the parasympathetic system. Chlorinated hydrocarbons used as insecticides stimulates the central nervous system. Insecticides are derived from plants and have rapid knockdown effect for insects.

Ques 16. Which of the following are used for cattle poisoning?

a)      Abrusprecatorius

b)      Calotropis

c)      None of the above            

d)      Both a & b

Answer. (d) Both a & b

ExplanationAbrusprecatorius is commonly known as Rosary pea, it produces poisonous effect when injected subcutaneously. Calotropis is known by local names such as ‘Madar’ and ‘Akdo’ and is found throughout India. It is used as suicide, homicide, infanticide and as cattle and arrow poison. In India, they are utilized for the malicious destruction of cattle.

Ques 17. Anions are isolated from viscera by?

a)      Acid steam distillation method

b)      Dialysis

c)      Alkali steam distillation

d)      Both a & b

Answer. (b) Dialysis

ExplanationToxic anions includes chlorate, borate, fluoride, iodide, etc. In some cases, anions are used as active species such as borate, oxalate, these anions are to be especially isolated in case of biological materials. Anions are sometimes found in combination with a cation, after which the organic matrix is destroyed with metals. Other anions ca be separated from the matrix by dialysis.

Ques 18. Volatile organic poisons are isolated by?

a)      Alkali steam distillation

b)      Dialysis

c)      Acid steam distillation                       

d)      None of the above

Answer. (c) Acid steam distillation

ExplanationAcid steam distillation method is utilized for compounds with a relatively high vapor pressure, which are immiscible in cold water. This method has both extraction and separation function as it can separate target volatile compound from non-volatile compounds.

Ques 19. Following is the example of carbamates insecticide

a)      Baygon

b)      Carbaryl

c)      Both

d)      None of the above

Answer. (c) Both

ExplanationCarbamate insecticides includes baygon, carbaryl, seven, etc. they act by inhibiting acetylcholinesterase, which is an enzyme that degrades acetylcholine. Carbamate are widely utilized as they are more degradable than organophosphates and have lower dermal toxicity.

Ques 20. Non-volatile organic drugs can be examined by following analytical technique

a)      AAS

b)      MS

c)      HPLC

d)      SDS-PAGE

Answer. (c) HPLC

ExplanationHPLC provide direct separations of non-volatile compounds using liquid mobile phase and solid stationary phase. The different substances in the sample injected distribute themselves according to their affinity with the two phases.

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