New synthetic opioids in biological and non-biological matrices: a review of current analytical methods

Abuse of new synthetic opioids is a worldwide rising issue posing a serious threat to the health of consumers. Unlike commonly abused drugs, which can be identified through routine drug testing, these new psychoactive substances may escape immunological screening tests and appropriate confirmation methods have not yet been developed and validated. Gas chromatography combined with mass spectrometry (GC–MS) and more frequently liquid chromatography tandem mass spectrometry (LC–MS/MS) as well as ultra high-liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) are the methods required to attack this analytical problem. The technologies are sufficiently sensitive and specific to be used with antemortem and postmortem specimens and also to disclose drug metabolism for substances used in very low doses, resulting in minute concentrations in biological matrices. An updated review and current trends concerning analytical methods for the determination of illicit fentanyl analogues and other new synthetic opioids at risk of abuse is reported here for both ante- and postmortem biological matrices and non-biological specimens.