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FORENSIC SCIENCE

PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

Subject FORENSIC SCIENCE

Paper No and Title PAPER : 5, Forensic Chemistry & Explosives

Module No and Title MODULE : M7, Detective dyes

Module Tag FS_P5_M7

TABLE OF CONTENTS

1. Learning Outcomes 2. Introduction: Bribery 3. Provisions Under I.P.C.

4. Detective Dyes 5. Chemistry of Phenolphthalein 6. Chemistry of Anthracene 7. Sample Collection 8. Forensic Analysis

9. Summary

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FORENSIC SCIENCE

PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

1. Learning Outcomes

After studying this module, you shall be able to know

• What does the term ‘Bribery’ actually mean?

• About the legal definition and penal provisions of bribery

• What are Detective Dyes?

• About the chemistry of Phenolphthalein and Anthracene, and

• About the sample collection and forensic analysis of detective dyes in trap cases

2. Introduction: Bribery

Bribery is an act of giving money or gift for altering the behavior of the recipient, where the gift is of a dishonest nature. Bribery constitutes a crime and is defined by Black's Law Dictionary as the offering, giving, receiving, or soliciting of any item of value to influence the actions of an official or other person in charge of a public or legal duty.

Gifts of money or any other item of value of an open nature to the recipient where it is otherwise available to others on an equivalent basis, and not for dishonest purposes, is not bribery.

Similarly, offering a discount or a full or partial refund to all purchasers of the same kind, quality and quantity of product or service, is called a legal rebate, and is not bribery. For example, it is legal for a employee of a Public Utilities Commission involved in electric rate regulation to accept a rebate on electric service that reduces their cost for electricity, when the rebate is available to other residential electric customers. If the rebate was done to influence them to look favorably on the electric utility's rate increase applications, however, that would be bribery, and unlawful.

Thus, bribe could be defined as a gift bestowed to influence the recipient's conduct. It may be any money, good, right in action, property, preferment, privilege, emolument, object of value, advantage, or merely a promise or undertaking to induce or influence the action, vote, or influence of a person in an official or public capacity.

3. Provisions under I.P.C.

Section 171 B of Indian Penal Code defines bribery and section 171 E deals with the punishment of bribery:

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FORENSIC SCIENCE

PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

Section 171 B: Bribery

(1) Whoever—

(i) gives a gratification to any person with the object of inducing him or any other person to exercise any electoral right or of rewarding any person for having exercised any such right; or

(ii) accepts either for himself or for any other person any gratification as a reward for exercising any such right or for inducing or attempting to induce any other person to exercise any such right; commits the offence of bribery: Provided that a declaration of public policy or a promise of public action shall not be an offence under this section.

(2) A person who offers, or agrees to give, or offers or attempts to procure, a gratification shall be deemed to give a gratification.

(3) A person who obtains or agrees to accept or attempts to obtain a gratification shall be deemed to accept a gratification, and a person who accepts a gratification as a motive for doing what he does not intend to do, or as a reward for doing what he has not done, shall be deemed to have accepted the gratification as a reward.

Section 171 E: Punishment for Bribery

Whoever commits the offence of bribery shall be punished with imprisonment of either description for a term which may extend to one year, or with fine, or with both:

Provided that bribery by treating shall be punished with fine only.

Explanation

“Treating” means that form of bribery where the gratification consists in food, drink, entertainment, or provision.

Classification of Offence

Non-cognizable—Bailable—Triable by Magistrate of the first class—Non-compoundable.

4. Detective Dyes

Detective dyes are the chemicals which are generally used in catching the bribers red handed.

In Trap related cases, although a number of different techniques have been employed using different chemicals such as fluorescent dyes, starch powder, phenolphthalein powders, anthracene powder, etc but phenolphthalein powder has remained most popular in India. Generally

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FORENSIC SCIENCE

PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

Phenolphthalein or Anthracene, are used during anticorruption operation as proof of acceptance of bribe.

5. Chemistry of Phenolphthalein

Phenolphthalein is an organic compound of the phthalein family with the chemical formula C20H14O4. It is a smooth white powder that is widely employed as an acid-base indicator and as a laxative.

Chemical Structure of phenolphthalein

The molecule has four forms, which correspond to the different colors it will become, based on the pH of the solution. It turns colorless in acidic solutions and pink in basic solutions. Just as there is a range of acidic and basic pH values, there is also a range in colors in which Phenolphthalein will appear. In strongly acidic solutions where the pH is at or near zero, Phenolphthalein will appear orange. In acidic to neutral solutions where the pH is between 0-8.2, Phenolphthalein will appear colorless. In basic solutions with pH values between 8.2 and 12, it will appear fuchsia. In strongly basic solutions above 12, Phenolphthalein will appear colorless like that of acidic or neutral solutions. Its unionized molecules are colourless whilst on ionization give colourless H+ and pink coloured phenolphthalein ions. The molecule has following four forms: Species H3In+ H2In In2− In(OH)3− Structure

pH <0 0−8.2 8.2−12.0 >13.0 Conditions strongly acidic acidic or near-neutral Basic strongly basic Color Orange Colorless pink to fuchsia Colorless Image

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FORENSIC SCIENCE

PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

5.1 Properties of Phenolphthalein

Property Molecular formula C20H14O4

Molar mass 318.32 g mol−1 Specific gravity 1.277 at 32°C Melting point 260 °C

Log Kow 2.41 Vapour pressure 6.7 × 10–13 mm Hg at 25°C

Dissociation constant (pKa) 9.7 at 25°C Density 1.277 g cm−3, at 32 °C

Solubility in water Insoluble Solubility in other solvents Insoluble in benzene, very soluble in

ethanol and ether, slightly soluble in DMSO

6. Chemistry of Anthracene

Anthracene (C14H10) is a solid polycyclic aromatic hydrocarbon consisting of three fused benzene rings. It is a constituent of coal tar. Anthracene is used in the production of the red dye alizarin and other dyes. It is colourless but shows blue (400-500 nm) fluorescence under ultraviolet light.

Chemical Structure of Anthracene

6.1 Properties of Anthracene

Property Molecular formula C14H10 Molar mass 178.23 g mol−1 Boiling Point 340 °C, 613 K, 644 °F Melting Point 218 °C, 491 K, 424 °F Density 1.25 g/cm³ at 19.85 °C, Solid

0.969 g/cm³ at 220 °C, liquid Solubility in water Insoluble Solubility in other solvents Methanol: 0.0908 g/100 mL

hexane: 0.164 g/100 mL

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PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

6.2 Chemistry of Fluorescence

Anthracene photodimerizes by the action of UV light:

The dimer, called dianthracene (or sometimes paranthracene), is connected by a pair of new carbon-carbon bonds, the result of the cyclo-addition. It reverts to anthracene thermally or with UV irradiation below 300 nm. The reversible dimerization and the photochromic properties of anthracenes are the basis of potential applications. Substituted anthracene derivatives behave similarly. The reaction is affected by the presence of oxygen.

7. Sample Collection

Generally in trap cases Phenolphthalein or Anthracene are used by various investigating agencies like Anti corruption branch of (CBI) and Vigilance Department.

7.1 In Case of Phenolphthalein

Phenolphthalein powder is generally applied in small quantity on the currency notes and other objects that are likely to come in contact with hands of the perpetrator resulting in its transfer (Locard’s Exchange Principle).

The hands are washed with a colourless solution of sodium carbonate (or sometimes with lime water), which becomes immediately pink confirming the touching of currency notes/ transferred of phenolphthalein to the hands. Pink to deep red colour is developed depending upon the quantity of phenolphthalein involved. These washings are being collected and sent to the forensic laboratories along with other relevant materials for analysis. It gradually fades and sometimes becomes colourless at the time of trial in the court. This creates unnecessary doubt and investigating officer is put in an awkward position. However, this phenomenon can be explained by the scientist on scientific basis that the colour of the phenolphthalein fades due to its breaking down into 2(4 –hydroxy benzoyl) benzoic acid and phenol in alkali medium.

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PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

7.2 In Case of Anthracene

Anthracene powder is now rarely used for this purpose in trap cases as it does not pose such problem of colour fading and has an advantage because of its fluorescence property. The hands/clothes of the suspect can be immediately examined under ultra violet light, violet/blue fluorescence and it can be clearly perceived. This proves direct contact of the suspect with currency notes. Pure anthracene shows blue fluorescence but impure anthracene due to presence of tetracene, naphthacene, etc. shows yellow with green fluorescence. The Hands/object can be wash with ethyl alcohol for the forensic examination.

8. Forensic Analysis

8.1 Tests for Phenolphthalein

8.1.1 PH Test

A pH value of more than 9 (pH range 8.3-10) with pink /red colour indicates the positive test for the presence of phenolphthalein.

8.1.2 Acid –Alkali Test

On adding a few drops dilute hydrochloric acid, the pink colour of the exhibit disappears. After this on adding a few drops of dilute solution of sodium hydroxide in water, the pink colour reappears. Appearing and disappearing of pink colour indicates the positive test for the presence of phenolphthalein

8.2 Instrumental Analysis of Phenolphthalein

8.2.1 Thin Layer Chromatography

Operating Conditions:

Stationary Phase: TLC plate coated with silica gel G.

Mobile Phase: Chloroform and Acetone (80:20)

Developing Reagent: Spray with dilute sodium hydroxide solution and then acidified potassium permanganate solution after visualization observed under U.V. light for fluorescence.

8.2.2 UV Spectroscopy

A Normal UV spectrum of phenolphthalein is known to show maxima at 277 nm in methanol.

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PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

8.3 Tests for Anthracene

8.3.1 UV Test

Under ultra violet light anthracene shows Violet/blue/green colour fluorescence.

8.4 Instrumental Analysis of Anthracene

8.4.1 Thin Layer Chromatography

Operating Conditions § Stationary phase : Silica gel G § Mobile phase : Heptane : Hexane § After visualization observe the plate under UV light for fluorescence.

8.4.2 Gas Liquid Chromatography

Operating Conditions § Detector : Flame ionization § Column : S S column 1/8 inch dia. 2 meter length § Packing : 10% S E 30 80/100 chromosorb W-HP § Carrier Gas: Nitrogen § Flow rate : 25 ml/min § Injector temperature : 2500C § Column temperature : 2200C Isothermal § Detector temperature: 2500C § Sample preparation : In ethanol

9. Summary

• Bribery is an act of offering, giving, receiving, or soliciting of any item of value to influence the actions of an official or other person in charge of a public or legal duty.

• Section 171 B in Indian Penal Code defines bribery and section 171 E deals with the punishment of bribery.

• Generally Phenolphthalein or Anthracene, are used during anticorruption operation as proof of acceptance of bribe.

• Phenolphthalein is an organic compound of the phthalein family with the chemical formula C20H14O4. It is a smooth white powder that is widely employed as an acid-base indicator.

• Anthracene (C14H10) is a solid polycyclic aromatic hydrocarbon consisting of three fused benzene rings. It is colourless but shows blue (400-500 nm) fluorescence under ultraviolet light.

• Phenolphthalein powder is generally applied in small quantity on the currency notes and other objects that are likely to come in contact with hands of the perpetrator resulting in its transfer.

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PAPER No.5: Forensic Chemistry MODULE No. 7 : Detective Dyes

• A number of tests and instrumental techniques are applied for the analysis of such transferred Phenolphthalein and Anthracene.

• The preliminary screenings of Phenolphthalein or Anthracene powder are done by Colour Test and PH Test.

• The confirmatory and instrumental tests are done by Thin Layer Chromatography and UV Spectroscopy.