Devices, and methods of use thereof, receivable by autosamplers for processing fluids contains suspended solids and solubles in, for example, solid phase extraction, include an inlet chamber in fluid communication with an outlet chamber through an integral fluid pathway. One or more autosampler needle(s) may inject the fluid into the inlet chamber, which contains a separation medium through which the injected fluid flows prior to flowing into the outlet chamber, from which fluid may be withdrawn by the autosampler needle(s). A pressure tight seal may be formed between the needle(s) and inlet chamber, and backflow is preventable from the outlet chamber to the inlet chamber. Numerous embodiments of the device are described, including well plate configurations and structures graspable by autosampler robotic devices and/or which may be held in autosampler trays.