Charge Titrations and Zeta Potential Determination – T70, DL53, DL28 (Mettler Toledo); ZetaOszi Titration techniques (pH-potentiometric, conductometric, and polyelectrolyte) are commonly used to determine the charging behaviour of various polyelectrolytes including charged polysaccharides in a solution or in a suspension (fibres, pulp, foils, membranes, etc.). They provide the information about: (1) the amount/charge density of dissociable polymer’s functional groups (acidic or basic), (2) the corresponding pK values, as well as (3) the point of zero charge/isoelectric point. All three titration techniques are often used in combination with each other in order to correlate the results and retrieve additional data about the surface behaviour of polymers. One can retrieve information about the adsorption/desorption of polymers to solid substrates (functionalisation of cellulosic materials), the surface functionality of polymers in solution and of solid substrates, and the influence of specific functional groups on the material’s bioactivity to mention the most important properties. As another complimentary technique we are using zeta potential determinations to validate the results from the titrations. Suitable samples: fibers, pulps, films in swollen and wet state. Model surfaces can be analyzed only with streaming potential analysis.