Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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RAN 4090/ll7
The invention relates to a ring of cells for analy-
iical devices operating on the centrifugal principle and
photometrically measuring a sample for analysis, the system
comprising a number of individual cells disposed in a
circle and made of thermoplastics, each cell having three
10 interconnected chambers, i.e. a sample chamber, a reagent
chamber and a photometric measuring chamber, the major
axes of the sample chamber and the reagent chamber being at
right angles to the plane of rotation and the major axis of
the measuring chamber coinciding with the plane of rotation.
Some known analytical devices operate on the centri-
fugal principle and make photometric measurements of the
sample for analysis. They are preferably used when very
small samples have to be analysed in a short time and where
20 the nature of the analysis is such that photometric methods
can be used. This applies particularly to clinical chemical
analysis, where it is frequently necessary e.g. to determine
glucose, urea, uric acid, cholesterol or total protein,
albumin, bilirubin or metal ions in the blood, serum, plas-
26 ma, urine or liquid obtained by puncture, e.g. liquor orsimilar biological solutions. The amount of material avai-
lable for investigation is frequently only a few micro-
litres and the time available for analysis is often limited
to a few minutes. In such cases it is advantageous to use
30 automatic analytical devices operating by the aforementioned
centrifugal method.
The devices comprise a ring of cells containing a
predetermined number of individual cells. Each individual
35 cell has at least three chambers, i.e. a sample chamber, a
reagent chamber and a photometric measuring chamber. The
sample and the reagent are poured into the appropriate cell
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chambers when the rotor is motionless, so that the two
liquids initially remain separate. After the cells have
been filled, the analyzer is started up, whereupon the
centrifuge first rotates at high speed. As a result of
centrifugal force, the sample for analysis and the rea-
gent liquid are expelled from the two chambers into which
they were previously poured, and are combined and raised
to the photometric measuring chamber. After a predeter-
mined time, the photometric scanning of the individual mea-
suring chamber begins, and usually the peripheral speed ofthe centrifugal part of the analyzer is reduced. The extinc-
tion recorded by the measuring part is evaluated by a
computer and is usually immediately expressed as the result
of the analysis.
Known centrifuaal analyzers of this kind, e.g. as
described in the "Cobas-Bio" pamphlet published in 1978
by Messrs. F. Hoffmann-Laroche & Co. of Basle, comprise a
number of individual cells combined to form the aforemen-
tioned ring of cells by means of a separate ring. The ring
has a number of radial slots in which the cells with their
oblong measuring chambers are inserted and retained. The
advantage of the device is that individual cells can be
thrown away after use and destroyed if necessary, which is
particularly important in the analysis of pathogenic
liquids.
German Offenleyungsschrift 27 26 219 discloses a cell
system for centrifugal analyzers having a different con-
struction. According to the last citation, the cell systemcomprises two superposed discs of flexible thermoplastics,
the lower disc being formed with a number of compartments
and the top disc being stuck or welded to the bottom disc
and, in the process, covering at least part of each com-
35 partment. Cell systems of this kind form an inseparableunit which, as before, has good mechanical stability but
where it is impossible to remove individual cells from the
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unit and destroy them separately.
An object of the invention is to simplify and thus
reduce the cost of annular cell systems of the kind des-
6 cribed in the "Cobas-Bio" pamphlet. The object of the
simplification is to do without the retaining ring without
qiving up the advantage of separating individual cells.
To this end, according to the invention, each cell at
10 its upper edge has a laterally projecting tongue which
completely or partly overlaps the adjacent cell and is
secured thereto. According to a particularly advantageous
feature, the tongue is secured, preferably by welding, to
the top edge of the next-but-one side wall of the next
cell. As a result of this feature, the ring of cells has
sufficient dimensional stability and strength to withstand
normal handling and the stress during centrifuging. It has
been found that the required strength can also be obtained
if the tongue covers only the rear-part of the neighbouring
20 cell in the radial direction but leaves the front part
uncovered. This is advantageous in that it facilitates the
process of filling individual cells when the ring is at a
standstill.
Thus the present invention provides a ring of cells for
analytical devices operating on the centrifugal principle
and photometrically measuring a sample for analysis. The
system comprises a number of individual cells disposed side
by side in a circle and made of thermoplastics, each cell
having an upper edge, a sample chamber, a reagent chamber
30 and a photometric measuring chamber. These chambers are
interconnected with each other, by connecting apertures,
the major axes of the sample chamber and the reagent chamber
being at right angles to the place of rotation
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and the major axis of the measuring chamber coinciding
with the plane of rotation. Each cell has at its upper
edge a laterally projecting tongue which completely or
partly overlaps, an adjacent cell and is rigidly secured
thereto.
According to another proposed feature of the inven-
tion, each cell has a web above the connecting aperture
between the sample chamber and reagent chamber on the
one hand and the measuring chamber on the other hand.
The web can be constructed with thick portions at
its ends and so that the lateral end surfaces of the web
of neighbouring cells abut and are interconnected if
required. The webs prevent the sample or reagent liquid
from accidentally reaching the relatively sensitive com-
ponents of the centrifugal analyzer. The webs also
support one another and further increase the strength of
the ring of cells. The webs also combine to form a
convenient handle for holding
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the device. In spite of the resulting considerable radial
strength, which easi1y withstands stresses during centri-
fuging, it is possible to break individual cells from
the ring and use them as partial segments in the analy-
zer when only a few samples needs to 'oe analyzed.
The invention will now be described in detail with re-
ference to the accompanying drawings, in which:
Fig. l is a perspective view of an embodiment of a
single cell in a ring of cells according to the invention,
and
Fig. 2 is a plan view of a portion of a ring of cells
15 according to the invention.
Fig. l shows an individual cell (general reference
l). The cell is made up of a total of three chambers, i.e.
. a reagent chamber 2, a sample chamber 3 and a photometric
; 20 chamber 4. The major axes of the reagent chamber and the
sample chamber are at right angles to the plane of rota-
tion of the analyzer whereas the major axis of the mea-
suring chamber 4 is in the plane of rotation. Fig. l also
shows that the back wall of the reagent chamber, in centri-
25 fugal direction, is oblique. The corresponding wall of the
sample chamber (not shown in the drawing) is likewise ob-
lique. If the ring of cells, i.e. each individual cell,
is centrifuged, the liquid in the reagent chamber and the
sample chamber rises along the oblique wall and the liquids
30 mix and enter the measuring chamber 4.
According to the invention, the upper edge 6 of each
cell l has a laterally projecting tongue 7 which partly
or completely covers and is secured to the neighbouring
35 cell in the ring. Fig. 2 shows a preferred embodiment in
which tongue 7 is secured to the top edge 80f the next-
but-one side wall 9 of the next cell l', preferably by
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welding. One result of this overlap is that the reagent
and cell chambers, which are open at the top, are covered
by the overlapping tongue. Another result is that the
entire ring of cells has higher stability, since the top
edges of the chamber walls abut the under-surface of the
tongue.
The drawing also shows that in the embodiment depic-
ted therein tongue 7 covers only the rear part, in the
10 centrifugal direction, of the corresponding adjacent cell.
According to another proposed feature of the invention,
each cell l has a web ll above the connecting aperture
l0 between the sample chamber and reagent chamber on the
15 one hand and the measuring chamber on the other hand. The
web preferably has thick ends 12, which increases the sta-
bility and also enables the lateral end-faces 13 of the
webs to abut and be interconnected if required, likewise
by welding or sticking. The webs thus form a handle which
20 simplifies manipulation of the ring of cells.
Preferably the ring of cells is made of transparent,
unstabilized polymethyl methacrylate (PMMA).
