An adapter for a sliding head of a sample processing system is provided that includes a plate and a magnet mounting recess wall. The plate includes a top surface, a bottom surface, a front wall extending between the top surface and the bottom surface, and a back wall extending between the top surface and the bottom surface. The magnet mounting recess wall is mounted to the top surface. The magnet mounting recess wall is configured to accommodate a magnet of a sliding head of a sample processing system. At least a portion of the bottom surface is curved in a first direction from the front wall to the back wall and is concave relative to the top surface.