Trap Case Chemicals (Phenolphthalein, Sodium Carbonate) and Bribery Casework (UGC-NET Unit IV)

Advanced UGC-NET Forensic Science Unit IV drill on trap-case chemistry and bribery casework. Coverage includes phenolphthalein indicator chemistry (colourless lactone form below pH 8.2, pink quinoid form above pH 8.2, pKa near 9.4 with a second transition to colourless above pH 13), sodium carbonate as the alkaline wash reagent (typically a five to ten percent aqueous solution), coating of currency notes with phenolphthalein powder, hand-wash and currency-wash tests during a trap raid, faint UV fluorescence of phenolphthalein, and laboratory confirmation by ethanol or methanol extraction followed by alkaline colour test and thin-layer chromatography at the State or Central FSL. Legal coverage spans the Prevention of Corruption Act 1988 (Section 7 on bribery, Section 13 on criminal misconduct, Section 20 statutory presumption), the PC (Amendment) Act 2018 (criminalising the bribe-giver and tightening definitions), the role of CVC and the Vigilance Manual 2021, CBI Crime Manual 2020 trap procedure, panchnama drafting with two independent witnesses, and case law including State of Maharashtra v. P.K. Bhasin AIR 2007 SC 1411, State of UP v. Zakaullah (1998), and Subramanian Swamy v. Director CBI (2014). Indian forensic context covers CFSL Chandigarh, CFSL Hyderabad, state ACB labs, and DFSS procedural manuals.