Procedure for photometric measurement of liquids in reaction vessels, and reaction vessel

A procedure for photometric measurement of liquids in a reaction vessel in an automatic analyser, with a radiation flow having its course perpendicular to a row of the reaction vessel, so as to provide a reliable and positively operating measuring method for the photometric measurement of the liquids. The procedure is characterized in that the radiation flow and the reaction vessel are in movement relative to each other during the measurement. The invention affords the advantage of improved accuracy of measurement and improved reliability since it becomes possible, by measuring a moving object and at the same time calculating the mean of the radiant flux over accepted portions of the signal, to eliminate the error of measurement introduced by a dirt particle or by a scratch. The invention also concerns a row of reaction vessels employed in the procedure, wherein each reaction vessel is contiguous to the next and separated by a wall. The row of reaction vessels is characterized in that the bottom of each reaction vessel consists of a lens focussing luminescence radiation. This affords the advantage that the lens enables a luminiscence measurement to be performed simultaneously with the photometric measurement.

BACKGROUND OF INVENTION 
The present invention concerns a procedure for photometric measurement of 
liquids in a reaction vessel by means of a radiation flow with a course 
perpendicular against a row of reaction vessels in an automatic analyser. 
In procedures and devices known in the art, for instance, circular reaction 
vessels resembling test tubes are used, the measurement on the liquid in 
the reaction vessel being made from their side, perpendicularly to the 
vessel. The most serious drawback is then the fact that the measuring 
signal is altered by the circular shape of the tubular reaction vessel, 
whereby it is possible to obtain an exact reading only at the centre of 
the vessel. Therefore, mean values cannot be used at all, with the 
consequence that dirt particles and scratches easily cause errors in the 
results of measurements. In addition, the procedure is slow, and 
automation of the sample manipulation is difficult to arrange. 
In another procedure known in the art, rows of reaction vessels (so-called 
cuvettes) are employed, which often have straight measuring surfaces. One 
makes in that case the measurement on one vessel at a time, directing the 
radiation flow through the liquid under measurement from one side of the 
reaction vessel. Dirt particles and scratches on the vessel still 
constitute a detriment and give rise to measuring errors. Moreover, the 
procedure is slow and automation of the sample movements is difficult 
because in the method two directions of movement must be provided for the 
cuvettes and these have to be synchronized with each other. 
SUMMARY OF INVENTION 
The object of the present invention is to eliminate the drawbacks mentioned 
and to provide a reliable and positively operating measuring method for 
photometric measurement of liquids. The procedure of the invention is 
characterized in that the radiation flow and the reaction vessel are in 
motion relative to each other during the photometric measurement of the 
liquid. 
The procedure according to an advantageous embodiment of the invention is 
characterized in that by means of the radiation flow used for measurement 
of liquids the distance between reaction vessels and the location of the 
reaction vessels is also measured. The advantage is hereby gained that no 
mode or means used need be specifically devised for locating the reaction 
vessel, and the position fixing need not be synchronized. 
The procedure according to another advantageous embodiment is characterized 
in that of the radiation flow the mean value is measured over the entire 
useful length of the reaction vessel. 
The advantage afforded by the invention is improved accuracy of measurement 
and reliability due to the circumstance that it is possible, by making the 
measurement on an object in motion and by calculating at the same time the 
mean of the radiation flux over accepted portions of the signal, to 
eliminate the error of measurement caused by a dirt particle or a scratch 
on the vessel. 
The procedure according to yet another advantageous embodiment is 
characterized in that, in order to move the row of reaction vessels, this 
row is grasped in one direction of travel by an engagement member. The 
advantage is now that the moving of the reaction vessel row, or the 
cuvette, can be made simple. The same engagement member which makes the 
measurement possible also makes possible the cuvette pick-up operation. 
The invention also concerns the reaction vessel row employed in the 
procedure, in this row each reaction vessel being contiguous to the next, 
separated by a common wall to form a cuvette. The reaction vessel row 
according to the invention is characterized in that the bottom of each 
reaction vessel consists of a lens focussing luminescence radiation. 
Hereby the advantage is gained that the lens enables a luminescence 
measurement of the liquid to be carried out simultaneously with the 
photometric measurement. 
The reaction vessel row according to an advantageous embodiment is 
characterized in that at one end at least of the reaction vessel rows 
there is a mating member presenting a portion bevelled in the direction in 
which the engagement member approaches. 
The reaction vessel row according to another advantageous embodiment is 
characterized in that at one end at least of the reaction vessel row there 
is a mating member carrying a magnet bit or a bit of magnetizable 
material. 
These two embodiments afford the advantage that the engaging member may 
enter into engagement with a row of reaction vessels by one single 
movement, in only one direction.

The procedure is used to measure various liquids photometrically in 
reaction vessels 1 which constitute a row of reaction vessels 2. The row 
of reaction vessels, or the cuvette 2, is provided with a mating member 3 
or 4, which is grapped by a parallel movement of an engagement member 6 or 
7 and the cuvette is transported to a location where it is filled with the 
liquids to be measured. After an adequate reaction and stabilizing perod 
for the liquids, the cuvette 2 is moved with the same engagement member 
past the measuring head of a photometric unit in such a way that the 
electronic signal response to the measuring radiation flux 11 passing 
through the liquid and striking the detector will be as shown in FIG. 1. 
From the response by the detector is elicited by automatic signal analysis 
the location S1, S2, etc. of each reaction vessel and the effective length 
of travel S1, S2, etc. used for the measuring of each liquid sample 
between inner walls 13 of each reaction vessel 1, wherein any portions e 
of the signal deviating substantially from the average signal level are 
disregarded, such signal portions being possibly due to scratches on the 
surfaces of the cuvette, to dirt particles, etc. The mean of the signal 
calculated from the said effective lengths of travel corresponds to the 
absorption properties of each quantity of liquid contained in the reaction 
vessels or cells of the cuvette as closely as possible. 
It is possible with the same motion of the cuvette to measure also the 
luminescent radiation from each liquid quantity directed through the lens 
8 having a suitable radius 12 and constituting the bottom of the reaction 
vessel 1 to a luminescent radiation detector. 
To the purpose of automatically moving the linear cuvette 2 in a way making 
the measuring procedure feasible, the measuring apparatus is provided with 
the engagement member 6 or 7 which becomes engaged by a single 
unidirectional motion with a mating member 3 or 4 on the cuvette 2. 
The engagement member engages either a suitably shaped projection 3 on the 
cuvette 2, or of a piece of material 4 capable of being attracted by a 
magnet. In the former case, the spring-loaded part 9 of the engagement 
member 6 yields to the bevelled portion 5 of the mating member, until the 
tip 10 of the engagement member has passed the bevelled face 5 and the 
spring force locks the cuvette 2 to the engagement member 7. An engagement 
member operating with magnetic force, consisting of a piece of 
magnetizable material suitably shaped or of a permanent magnet 4, is 
gripped with a permanent or electromagnetic engagement member 7. 
It is obvious to a person skilled in the art that the invention is not 
exclusively confined to the embodiment described in the foregoing and that 
it may vary within the scope of the claims stated below.