Analysis of Illicit Street Heroin Seized in Pakistan by Gas Chromatography–Mass Spectrometry (GC‐MS) for Identification of Adulterants and Impurities. - Usman, Muhammad; Baig, Yawar; Naseer, Abid; Nardiello, Donatella; Quinto, Maurizio; Honeychurch, Kevin (International Journal of Analytical Chemistry, 2026)