Fentanyl and fentanyl analogues represent a current and emerging threat in the United States as pure illicit narcotics and in mixtures with heroin. Because of their extreme potency, methods to safely and rapidly detect these compounds are of high interest. This work investigates the use of thermal desorption direct analysis in real time mass spectrometry (TD-DART-MS) and ion mobility spectrometry (IMS) as tools for the rapid and sensitive (nanogram to picograms) detection of fentanyl, 16 fentanyl analogues, and five additional opioids. Competitive ionization studies highlight that detection of these compounds in the presence of heroin is readily achievable, down to 0.1% fentanyl by mass with TD-DART-MS. With IMS, detection of nanogram levels of fentanyl in a binary fentanyl and heroin mixture is possible but can be complicated by decreased resolution in certain commercial instrument models. Modifications to the alarm windows can be used to ensure detection of fentanyl in binary mixtures. Additionally, three complex background matrices (fingerprint residue, dirt, and plasticizers) are shown to have a minimal effect of the detection of these compounds. Wipe sampling of the exterior of bags of questioned powders is shown to be a safe alternative method for field screening and identification, removing the need to handle potentially lethal amounts of material.

We report the facile fabrication of high-quality, robust alkanethiolate self-assembled monolayers (SAMs) on germanium substrates. Our approach to produce SAMs on technologically important substrates takes advantage of the many strategies previously developed for gold-thiol self-assembly. Direct self-assembly of alkanethiols on germanium is impeded by the presence of the native germanium oxide. Using a mixture of water and ethanol, we create an environment where both adsorbate and oxide are sufficiently soluble to enable SAM deposition in a single step. By manipulating reaction conditions, monolayers form spontaneously on untreated germanium, which opens new avenues for the exploitation of self-assembly on semiconductor surfaces. While our analyses initially focused on 1-dodecanethiol on Ge(100), this method is robust and we have extended its use to include a range of adsorbates on Ge(100) as well as to the Ge(111) and Ge(110) substrates.

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Continuing efforts to combat the opioid crisis in the U.S. require technologies that can detect the presence of fentanyl and fentanyl-related substances for multiple applications, including law enforcement and border protection.