The name Magnetic Nanoparticles (MNP) describes a range of very fine particles, such as iron oxides. MNPs have found various applications in the medical sector, from use in imaging, to treatment of cancerous cells. The combination of MNP with a specific ligand (a molecule that binds to another usually larger molecule) can lead the particles to associate themselves with specific cells (such as tumours). Imaging methods can then be used to locate the amalgamation, using MRI or precise magnetometers. MNPs can also be used for targeting cancerous cells and treatment. In this case, an AC magnetic field can be used to induce heat in the MNP, thus destroying the cancerous cells. The quality of MNPs can be assessed by many means, some requiring complex laboratory equipment. However, it has been shown that magnetic susceptibility measuring instruments including MS3, and MS2B or MS2G) can be used to assess whether the particles meet required parameters, and do so much more quickly than other laboratory-based methods. This enables rapid checking of production batches of MNPs.