Sample purity and composition
Mass photometry is a new mass measurement approach; in which the mass of molecules can be determined by how they interact with light. The technique benefits from low sample requirements and quick acquisition times (<2 minutes per run), and the measurement is made at the single molecule level without the need for any labels.
Mass photometry measures the molecular mass of proteins and protein assemblies in solution with high accuracy. The mass photometry signal scales linearly with the known sequence mass of proteins (as well as other biomolecules) and is independent of their shape. As a result, via simple calibration, mass photometry enables the mass measurement of unknowns with high accuracy (<5 kDa, 1.9% average).
Data from Young et al, Science, 2018, 360 (6387), p423-7.