Shencheng Ge

Magneto‐Archimedes levitation (MagLev) enables the separation of powdered mixtures of illicit drugs (cocaine, methamphetamine, heroin, fentanyl, and its analogues), adulterants, and diluents based on density, and allows the presumptive identification of individual components. Small samples (mass <50 mg), with low concentrations of illicit drugs, present a particular challenge to analysis for forensic chemists. The MagLev device, a cuvette containing a solution of paramagnetic gadolinium(III) chelate in a non‐polar solvent, placed between two like‐poles‐facing NdFeB magnets, allowed separation of seven relevant compounds simultaneously. In particular, initial separation with MagLev, followed by characterization by FTIR‐ATR, enabled identification of fentanyl in a sample of fentanyl‐laced heroin (1.3 wt % fentanyl, 2.6 wt % heroin, and 96.1 wt % lactose). MagLev allows identification of unknown powders in mixtures and enables confirmatory identification based on structure‐specific techniques.

Magneto‐Archimedes levitation (MagLev) enables the separation of powdered mixtures of illicit drugs (cocaine, methamphetamine, heroin, fentanyl, and its analogues), adulterants, and diluents based on density, and allows the presumptive identification of individual components. Small samples (mass <50 mg), with low concentrations of illicit drugs, present a particular challenge to analysis for forensic chemists. The MagLev device, a cuvette containing a solution of paramagnetic gadolinium(III) chelate in a non‐polar solvent, placed between two like‐poles‐facing NdFeB magnets, allowed separation of seven relevant compounds simultaneously. In particular, initial separation with MagLev, followed by characterization by FTIR‐ATR, enabled identification of fentanyl in a sample of fentanyl‐laced heroin (1.3 wt % fentanyl, 2.6 wt % heroin, and 96.1 wt % lactose). MagLev allows identification of unknown powders in mixtures and enables confirmatory identification based on structure‐specific techniques.

All matter has density. The recorded uses of density to characterize matter date back to as early as ca. 250 BC, when Archimedes was believed to have solved “The Puzzle of The King's Crown” using density.^[1] Today, measurements of density are used to separate and characterize a range of materials (including cells and organisms), and their chemical and/or physical changes in time and space. This Review describes a density‐based technique—magnetic levitation (which we call “MagLev” for simplicity)—developed and used to solve problems in the fields of chemistry, materials science, and biochemistry. MagLev has two principal characteristics—simplicity, and applicability to a wide range of materials—that make it useful for a number of applications (for example, characterization of materials, quality control of manufactured plastic parts, self‐assembly of objects in 3D, separation of different types of biological cells, and bioanalyses). Its simplicity and breadth of applications also enable its use in low‐resource settings (for example—in economically developing regions—in evaluating water/food quality, and in diagnosing disease).

Alle Materie hat Dichte. Die Aufzeichnungen der Verwendung von Dichte zur Charakterisierung von Materie gehen auf das Jahr ca. 250 v. Chr. zurück, als Archimedes das “Rätsel der Königskrone” mit Hilfe der Dichte gelöst haben soll.^[1] Heute werden Dichtemessungen zur Trennung und Charakterisierung einer Reihe von Materialien (inklusive Zellen und Organismen) und deren chemischen und/oder physikalischen Veränderungen in Zeit und Raum verwendet. Dieser Aufsatz beschreibt eine dichtebasierende Technik – magnetische Levitation, der Einfachheit halber nennen wir sie “MagLev” –, die zur Lösung von Problemen in den Bereichen der Chemie, Materialwissenschaft und Biochemie entwickelt wurde. MagLev hat zwei Hauptmerkmale – Einfachheit und Anwendbarkeit auf ein breites Spektrum von Materialien –, die sie für eine Reihe von Anwendungen nützlich macht (z. B. Materialcharakterisierung, Qualitätskontrolle von Plastik‐Fertigteilen, Selbstorganisation von Objekten in 3D, Trennung verschiedener Arten von biologischen Zellen, und Bioanalysen). Die Einfachheit und Anwendungsbreite ermöglichen auch den Einsatz in ressourcenschwachen Gebieten (z. B. bei der Bewertung der Wasser‐ und Lebensmittelqualität und bei der Diagnose von Krankheiten).