* The subject of the present application is a thermostated cuvette set in which the samples placed in ^ 5 the cuvettes are measured photometrically. The cuvette set can be thermostated to the desired temperature by means of a heat transfer medium.

In photometric analyzers, cuvette sets com¬ prising several sample cuvettes are frequently used.

10 In this way the measurements can be carried out rapidly and automatically. In view of accuracy of measurement and of convenience of automation, the most advantageous mode of performance is vertical measurement. This prin¬ ciple of measurement and the cuvette sets for vertical

15 measurement used therein are described, e.g., in the

Letters Patent FI 57,665 and FI 55,093 (equivalent, e.g., to the Letters Patent GB 1,486,210) as well as in the Letters Patent US 4,431,307, the cuvettes in the cuvette set described in the latter patent being placed on the

20 bottom of a basin-shaped frame.

In the measurements it is often important that the samples are precisely at a certain temperature. In such a case the cuvette sets with their samples must be thermostated. In prior-art thermostating solutions,

25 e.g., thermostating equipments placed outside the measurement equipment have been used (e.g., "FP-400 INCUBATOR", Labsystems Oy, Helsinki, Finland), in which the cuvette sets can be thermostated before measurement. Heating devices placed stationarily in the measurement

30 equipments themselves are also known, in which the heating takes place by means of heating plates. One apparatus of this sort is described, e.g., in the pub¬ lished Patent Application documents FI 843324 (corres¬ ponds, e.g., to the published Patent Application

35 EP 136,001 A3) .

It is also known in prior art to heat photo¬ meter cuvette sets by means of a heat transfer liquid.

This can be accomplished, e.g., by onto the cuvette set blowing air .of uniform temperature.

From the Letters Patent US 4,498,780, an equipment is also known in which a liquid heat transfer medium is used. One equipment in accordance with the said patent is provided with a thermostating basin open at the top, onto whose bottom a cuvette set of matrix- shape is attached. As to its construction, the cuvette set is a closed piece in which there are cylindrical recesses forming the cuvettes. Moreover, between the rows of cuvettes, there are ducts of rectangular section in which the heat transfer medium flows. The heat transfer duct may partly also extend to below the edges of the-cuvettes. In this solution, it has, however, not been possible to make sure that the medium is in equally good contact with each cuvette. Moreover, the heat transfer is quite inefficient, because the effective, sufficiently thin heat transfer face adjoining each cuvette is quite little. The object of the present invention is above all to provide a cuvette set used in photometers and thermostated by means of a medium and in which the transfer of heat into the various cuvettes is uniform and efficient. The cuvette set in accordance with the in¬ vention comprises a basin-shaped frame on. whose bottom there are permanently fixed cuvettes whose walls are substantially equally thick. Cuvettes are connected by means of partition walls to each other and to the walls of the basin so that a system of flow ducts is formed in which at least one flow duct by-passes each cuvette. Moreover, at least one inlet opening passes into the flow duct system, and at least one outlet opening passes out of same, so as to circulate the heat transfer medium. In the following, a preferred embodiment of the invention will be described in further detail. In the drawings related to the description, Figure 1 shows

a cuvette set of rectangular section as viewed from above, Figure 2 is a side view in section in the trans¬ verse direction, Figure 3 is a side view in section in the longitudinal direction, and Figure 4 is a side view 5 in section of the cover of the cuvette set in the longi¬

<- tudinal direction.

In the cuvette set for vertical measurement shown in Fig. 1, the bottom 1 and the outer walls 2 of the cuvette set form a basin-shaped frame, on whose

10 bottom the cuvettes 3 shaped as circular cylinders and having walls of uniform thickness are placed in a rec¬ tangular matrix 7 x 10. The bottom of each cuvette acts as an optical measurement window.

The edge of the bottom of the cuvette set is

15 surrounded by an elevation 4, which prevents scratching of the measurement windows against the base.

The cuvettes in each longitudinal line of cuvettes are interconnected by partition walls 5. An end cuvette in each line is additionally connected to

20 the end by means of an end partition wall 6 so that adjoining lines of cuvettes are always connected to opposite ends.

At the end of the cuvette set in its top portion there is an inlet opening 7, which passes into

25 the space between the first line of cuvettes and the side wall at the end of the line which is provided with ^■ an end partition wall. Correspondingly, the same end is provided with an outlet opening 8, which passes into the space between the last line of cuvettes and the side

30 wall. In this way, an unbranched flow duct is provided, which by-passes all the lines of cuvettes from both sides.

The cuvette set further includes a cover 9 covering the basin, which said cover is provided with openings 10 facing each cuvette. In the cover, near

35 the outlet opening, there is a projection, from which the temperature of the liquid present in the flow duct can be measured.

When a cuvette set described above is used, samples can be heated or cooled rapidly as required. Thereat, thermostating liquid of the desired temperature is fed in through the inlet opening 7. The direction of flow of the thermostating liquid can be reversed during the thermostating. In this way a temperature distribution as uniform as possible is obtained even in a large field to be thermostated.

If desired, the thermostating liquid can be coloured, e.g., black, whereby access of light from one cuvette to the adjoining cuvette is eliminated.

Of course, the cuvette set in accordance with the invention may also differ from what is described here as an example. What is essential is that the cuvette set is provided with a flow duct system along which the thermostating medium flows by-passing all the cuvettes.

Thus, for example, the partition walls may be placed in many different ways, and the flow ducts may be branched. The inlet or outlet openings may also be placed in the bottom or cover of the frame. There may also be several openings, in which case the system may have several separate flow ducts.

The cuvette bottoms may also be non-transparent if the light does not have to be passed through the bot- torn (e.g., measurement of luminescence from above).

Also, the shape of the cuvettes may vary, and ^• they need not be placed in straight lines. If desired, the temperature of the thermostating liquid may be meas¬ ured at different points of the duct. In principle, the arrangement may also be applied to cuvette sets measured by means of horizontal beams.

In principle, a gas may also be used as the thermostating medium.