A metering structure on a sample processing device, the sample processing device configured to be rotated about an axis of rotation, the metering structure comprising: a metering reservoir (118, 218, 268) configured to hold a selected volume of liquid, the metering reservoir including a first end and a second end positioned radially outwardly of the first end, relative to the axis of rotation; a waste reservoir (120, 220, 270) positioned in fluid communication with the first end of the metering reservoir and configured to catch excess liquid from the metering reservoir when the selected volume of the metering reservoir is exceeded, wherein at least a portion of the waste reservoir is positioned radially outwardly of the metering reservoir, relative to the axis of rotation; and a capillary valve (130, 230, 280) in fluid communication with the second end of the metering reservoir, wherein the capillary valve (130, 230, 280)is positioned radially outwardly of at least a portion of the metering reservoir, relative to the axis of rotation, and is configured to inhibit liquid from exiting the metering reservoir until desired; the metering structure further comprises: a valve chamber in fluid communication with an outlet of the capillary valve (130, 230, 280); a process chamber (150, 250) positioned to be in fluid communication with an outlet of the valve chamber; and a valve septum located between the valve chamber and the process chamber (150, 250), the valve septum having: a closed configuration wherein the valve chamber and the process chamber (150, 250) are not in fluid communication, and an open configuration wherein the valve chamber and the process chamber (150, 250) are in fluid communication, wherein the metering structure is unvented, such that the metering structure is not in fluid communication with ambience. a metering reservoir (118, 218, 268) configured to hold a selected volume of liquid, the metering reservoir including a first end and a second end positioned radially outwardly of the first end, relative to the axis of rotation; a waste reservoir (120, 220, 270) positioned in fluid communication with the first end of the metering reservoir and configured to catch excess liquid from the metering reservoir when the selected volume of the metering reservoir is exceeded, wherein at least a portion of the waste reservoir is positioned radially outwardly of the metering reservoir, relative to the axis of rotation; and a capillary valve (130, 230, 280) in fluid communication with the second end of the metering reservoir, wherein the capillary valve (130, 230, 280)is positioned radially outwardly of at least a portion of the metering reservoir, relative to the axis of rotation, and is configured to inhibit liquid from exiting the metering reservoir until desired; the metering structure further comprises: a valve chamber in fluid communication with an outlet of the capillary valve (130, 230, 280); a process chamber (150, 250) positioned to be in fluid communication with an outlet of the valve chamber; and a valve septum located between the valve chamber and the process chamber (150, 250), the valve septum having: a closed configuration wherein the valve chamber and the process chamber (150, 250) are not in fluid communication, and an open configuration wherein the valve chamber and the process chamber (150, 250) are in fluid communication, a valve chamber in fluid communication with an outlet of the capillary valve (130, 230, 280); a process chamber (150, 250) positioned to be in fluid communication with an outlet of the valve chamber; and a valve septum located between the valve chamber and the process chamber (150, 250), the valve septum having: a closed configuration wherein the valve chamber and the process chamber (150, 250) are not in fluid communication, and an open configuration wherein the valve chamber and the process chamber (150, 250) are in fluid communication, a closed configuration wherein the valve chamber and the process chamber (150, 250) are not in fluid communication, and an open configuration wherein the valve chamber and the process chamber (150, 250) are in fluid communication,