Phenolphthalein Test
Definition
Currency notes or articles are dusted with phenolphthalein powder before the trap. After acceptance, the suspect's right-hand wash in dilute sodium carbonate solution turns pink (phenolphthalein indicator above pH 8.2), proving contact with the marked money.
- Field
- Anti-corruption trap case procedure
- Indicator
- Phenolphthalein powder dusted on currency
- Reagent
- Dilute sodium carbonate hand-wash solution
- Positive result
- Pink colour above pH 8.2
Common questions
Why sodium carbonate specifically for the hand wash?+
Phenolphthalein is colourless in neutral or acidic conditions and only turns pink once the solution is alkaline, so sodium carbonate provides the mild alkalinity needed to reveal the residue without damaging skin or evidence.
Does a negative test rule out that the suspect touched the marked money?+
Not conclusively; the powder can be washed off, transferred incompletely, or degrade with time and handling, so a negative result is treated alongside other trap-case evidence rather than as proof of non-contact.
Is the phenolphthalein test used for anything besides trap cases?+
The same colour reaction is a classic presumptive test for blood (the Kastle-Meyer test), but in the trap-case context described here it is specifically a marker for physical contact with treated currency, not a bloodstain screen.
Related terms
- Anthrone Test
- Anthrone reagent in concentrated sulphuric acid gives a blue-green colour with sucrose, glucose and other carbohydrates. Used when the bribe is a...
- Form 95 / Sealed PB
- Personal-bag forwarding form used by ACB / CBI to transmit sealed exhibits (tainted notes, hand-wash bottle, panchnama articles) to the State FSL...
- Section 7 PC Act 1988
- Offence of a public servant accepting or attempting to accept any undue advantage (illegal gratification) other than legal remuneration. The substantive offence...
- Sodium Carbonate Hand Wash
- Mildly alkaline (about pH 11) wash solution collected in a sealed glass bottle from the suspect's hand or pocket. Alkalinity is needed...
- Trap Case
- A pre-arranged sting operation under the Prevention of Corruption Act 1988 in which a complainant pays marked tainted money or a marked...