Abstract: A cuvette is shaped cylindrically at one end in order to be placed in a standard microfuge and is designed to specifically remove unwanted contaminates by centrifugation. The lower part of the cuvette is shaped substantially smaller to collect liquids for direct analysis and has a shape that will conform to a variety of spectrophotometers for the measurement of the absorption of irradiation and at times the subsequent scattering of light from the liquid samples which at least in the regions of the windows or desired shape is of a transparent plastic or glass with an inner space. The upper opening of the cuvette is for filling and removing sample fluid and sample preparation in a centrifuge and the lower part projects downwards towards the floor of the measuring chamber and which comprises a smaller cross section than the upper part. A cuvette holder is designed to conform to the shape of the cuvette with an outer surface to conform to the specific measuring device.