A test-tube for clinical chemistry analysis made up of a plurality of cells, each one of the cells comprising a lower portion for the collection of the reagent and a side intermediate portion provided with an edge for the storage of the sample to be tested upon the mixing thereof with the reagent. The cells are disposed in a straight configuration. The operations of the mixing of the samples with the reagents and the simultaneous stirring inside all cells, may be carried out by imparting the test-tube with an angular motion about a longitudinal axis.

An integrally built, linear array of cuvettes is made of a plastic material. Every cuvette of the array has the same shape and dimensions. Neighboring cuvettes are connected to each other by a single web. Each of the single webs has a curved shape and each cuvette has means forming integral part thereof and serving for accurately positioning the cuvette into an opening of a cuvette holder and means for removably connecting the cuvette to the cuvette holder. Each cuvette has an upper chamber and a lower chamber having a common symmetry axis passing through the centers of both chambers. Each of the upper and lower chambers has a substantially cylindrical shape. The cross-section of the upper chamber at the central part thereof is larger than the cross-section of the lower chamber. The lower chamber has an open lower end. The upper chamber has an open top end and an annular bottom wall having a central circular opening which connects the upper chamber with the lower chamber. The inner surface of the bottom wall of the upper chamber (17) is part of a conical surface the cross-section of which forms an angle of about 80 degrees with the symmetry axis, so that there is an abrupt change of cross-section between the upper chamber and the lower chamber. A two-dimensional array of cuvettes comprises a plurality of linear cuvette arrays inserted into a cuvette holder having a matrix array of cuvette receiving openings. A system of two-dimensional cuvette arrays is built by stacking two or more of such two-dimensional arrays of cuvettes. Foil shaped layers serving, e.g. as a filter, are adapted to be attached to each cuvette to cover at least one opening thereof.

A multicuvette rotor which reduces unacceptable tendencies of reagent or a sample material to spontaneously move or "wick" from one chamber compartment to the other, resulting in premature conmingling of reactants, and of sample or reagent material to flow out of one or more of the radially outer loading ports during acceleration of the rotor for transfer of the sample or reagent material from inner chambers to corresponding outer chambers.

A method and apparatus are provided for use with a centrifuge to analyze reactants. The apparatus includes at least one cuvette having at least one chamber. The chamber has a radially outward wall which provides a base upon which reactants can be pelleted when the device is rotated about a centrifugal axis. Each cuvette includes one or more openings for introducing fluids to the cuvette and includes a channel positioned adjacent to the radially outward wall for removing fluids from the chamber. Pressure is applied to the chamber to force fluids therefrom, through the channel. A hold down device is also provided through which fluid and/or pressure may be passed with respect to the cuvette. The invention also provides a method for determining the existence and degree of agglutination of reactants in a first fluid suspension and contained in a single reaction vessel using a photodetector.