The bulk solvent can be easily replaced with different solvents, and solutions containing transmembrane proteins can also be added to study protein insertion (101) (Figure ) or potential-dependent structural changes (102). SEIRAS can also be used to monitor time-resolved in-situ processes, such as the expression and folding/inserting of transmembrane proteins into lipid membranes . The folding/insertion process and conformational changes can be tracked by the lineshape of amide bands over time.