Development of sampling, pretreatment and detection methods for ephedrine and related substances in complex samples

Ephedrine is an alkaloid derived from ephedra and generally present in common medicines. Due to the structure similarity between ephedrine and methamphetamine, criminals can use pharmaceutical preparations of ephedrine to make drugs. Hence ephedrine and related substances need to be strictly controlled during drug production, testing and use. The faster, simpler and more sensitive analytical techniques are very important for the administration of ephedrine-containing pharmaceutical preparations. This review summarizes the research on sampling, pretreatment and detection methods of ephedrine and related substances in various samples since 2010. Pretreatment methods typically include liquid–liquid extraction, solid-phase extraction, derivatization, and various microextraction methods, which are used for sample extraction, purification and enrichment to meet the analysis requirements. Detection methods include liquid chromatography-based methods, gas chromatography-based methods, supercritical fluid chromatography, capillary electrophoresis methods and so on. Further, we compared the advantages and disadvantages of various pretreatment and detection techniques, and summarized the development achievements and prospects in this field.