Abstract: A simple, robust and low-cost torsionally flexible, sealed drive that allows external drives to provide agitation within a container. A torsionally flexible tube is sealed to a torsionally rigid portion of a container. A second end of the tube is sealed to a driven element within the container. The driven element is coupled to a drive-shaft that is partly contained within the tube. Motion of the protruding end of the drive shaft imparts a corresponding motion to the driven element, while maintaining a water-tight seal between container and drive-shaft. One useful motion is a rotary oscillation. A stepper motor may operate via such a drive to impart a rotary oscillation to an impellor in a bioreactor, or mixing container, suitable for agitating a cell culture in a nutrient medium or hydrating a powdered media in water. The drive is suited to use in disposable bioreactors and mixers.

Abstract: The peroxide content of a non-aqueous medium is measured by a system including separate supplies for two carrier solutions, a first one containing an acid for acidifying the sample and the second containing an iodide compound for reacting with the peroxide(s) in the sample and producing a free iodine ion, such as I.sub.3.sup.-, and a flow-through detector, such as a colorimetric device. The sample and first carrier solution streams are controlled by a sample injection valve which is movable between a load position wherein the sample stream is routed to a sample waste collector via a sample loop and the first carrier solution stream passes through a first carrier solution conduit and is combined with a stream the second carrier solution prior to passing through the detector and a measure position wherein a slug of the sample is introduced into the first carrier solution conduit, mixed with the first carrier solution and combined with the second carrier solution prior to passing through the detector.