Minimizing the fiber property distribution would have the potential to improve the pulp properties and the process efficiency of chemimechanical pulp (CTMP). To achieve this, it is essential to improve the level of knowledge of how evenly distributed the sulphonate concentration is between the individual CTMP fibers. Since wood chips can vary in quality depending on pulpwood chipping method and sawmill chipping as well as on chip screening system it is challenging to develop an impregnation technology that allows for an even distribution of the sodium sulphite (Na2SO3) impregnation liquid. It is therefore necessary to be able to measure the distribution of sulphonate groups within the wood chips and individual fibers, i.e., on a micro-scale level. Typically, the degree of unevenness, i.e. the amount of fiber sulphonation and softening prior to defibration, is unknown on a micro-level due to excessively robust or complex processing methods. In the event that it existed, we could better understand how sulphonation works before defibration in order to improve impregnation. The strategy for improving the impregnation technology is to study different impregnation systems in lab and pilot scale on wood chips produced in different ways in a pilot scale pulpwood chipper and a pilot scale sawmill chipper. This is to minimize the difference in sulphonate content between different fibers. To study the influence of impregnation improving processes we have developed a laboratory scale miniaturized energy dispersive X-ray fluorescence (ED-XRF) method that can measure sulphur (S) distribution at fiber level.