Sample processing units useful for mixing and purifying materials, such as fluidic materials are provided. A sample processing unit typically includes a container configured to contain a sample comprising magnetically responsive particles, and one or more magnets that are in substantially fixed positions relative to the container. A sample processing unit also generally includes a conveyance mechanism configured to convey the container to and from a position that is within magnetic communication with the magnet, e.g., such that magnetically responsive particles with captured analytes can be retained within the container when other materials are added to and/or removed from the container. Further, a sample processing unit also typically includes a rotational mechanism that is configured to rotate the container, e.g., to effect mixing of sample materials disposed within the container. Related carrier mechanisms, sample processing stations, systems, and methods are also provided.