Trace elemental profile investigation of illicit heroin for forensic intelligence

Abstract

Abuse of illicit heroin is an endless threat to society and law enforcement. Beyond the routine procedure of detecting heroin in forensic laboratories, analytical information on the trace elemental profile of seized samples could aid investigations into establishing sample-to-sample linkages for forensic intelligence. This study is aimed at highlighting the grouping of seized illicit heroin samples based on their elemental profiles. A total of 155 seized heroin samples were analysed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and subsequently subjected to Principal Component Analysis (PCA). Among the 24 target elements measured, Ca, Na, Se, Zn, Al, Mn, Cd and Ba were the major impurities identified, while the remaining elements were present at trace levels. Decomposition of the elemental data by PCA generated two major clusters in a score plot, suggesting the possibility of clustering the various samples into two distinct groups. The ICP-MS technique was found to be sufficiently adequate to detect and quantify the 24 selected elements contained in illicit heroin samples. The histories of two distinct groups of elemental contamination may enable the establishment of a linkage among seized illicit heroin samples.