Selective Detection of Methamphetamine Hydrochloride Using Fluorescent Benzo[ghi]perylenetriimide Thin Films in a Single-Channel Detector·

Abstract

Rapid detection of trace-level quantities of illicit drugs is essential for those in law enforcement, customs, and border security. We report fluorescent benzo[ghi]perylenetriimide (BPTI) films incorporated into a simple device architecture that can selectively detect methamphetamine hydrochloride (MA•HCl) over 3,4-methylenedioxyamphetamine hydrochloride (MDA•HC), cocaine hydrochloride (cocaine•HCl), and fentanyl hydrochloride (fentanyl•HCl) with a limit of detection of 10 ng. We show that heating the drug salts generates a vapour in which the free-base drug and hydrogen chloride are in equilibrium with the salt. The free-base form is responsible for reversible quenching of the fluorescence via photoinduced hole transfer (PHT). The magnitude and shape of the response are dependent on the salt:free-base equilibrium and free-base volatility, which are to the left and highest, respectively, for MA•HCl. Finally, we show that a potassium carbonate filter can be used to preferentially enhance the magnitude of the fluorescence response for MA•HCl, improving its selective detection.