METHOD AND APPARATUS FOR THE MEASUREMENT OF THE PROPERTIES OF AN AGGLUTINATION

Abstract: A method for the measurement of the properties of an agglutination, a precipitate (4), or of a corresponding reaction result placed on the bottom of a vessel (2) by means of radiation and of a detector (3) that receives radiation. The beam of measurement (5) coming from the source of radiation (1) passes substantially in the direction of the vertical axis of the vessel, and the intensity of the radiation passing through, or reflected from, the precipitate on the bottom of the vessel is measured. In order to measure the formation, location, and form of the precipitate and/or the density or other properties of different points of the precipitate, a component field of limited area, out of the field of the vessel (2) bottom to be measured, is measured. The vessel (2) and/or the source of radiation (1) and/or the detector (3) is/are moved so that the component field subject to measurement moves along the field to be measured. The measurement result of the component field at each particular time under measurement is read constantly or at specified intervals for the purpose of processing and output of the information.

Description: METHOD AND APPARATUS FOR THE MEASUREMENT OF THE PROPERTIES OF AN AGGLUTINATION The present invention is concerned with a method for the measurement of the properties of an agglutination, a precipitate, or of a corresponding reaction result placed on the bottom of a vessel by means of radiation and of a detector that receives radiation, whereat the beam of measurement coming from the source of radiation passes substantially in the direction of the vertical axis of the vessel, and the intensity of the radiation passing through, * or reflected from, the precipitate on the bottom of the vessel is measured. The invention is also con¬ cerned with an apparatus for the implementation of the method, which apparatus comprises one or several detectors receiving radiation, the said detectors being located so that the measurement beam received by them passes substantially in the vertical direction of the vessel, as well as an output unit. Various tests based on agglutinations are in common use, e.g., in the case of blood-group identifi¬ cations, antibody determinations, and rheumatic-factor measurements. In blood-group analytics and in antibody determinations the agglutination of .red blood cells is concerned, whereas, e.g., the rheumatic factor is commonly measured by means of the agglutination of latex particles. It has been customary tc read the results of agglutination reactions visually. An experienced reader is also quite skilful in distinguishing between aggluti¬ nation and non-agglutination. Such a mode of output is, however, quite subjective, and this is why the result is not always completely reliable. In clear situations with strong agglutination, visual reading is certainly no problem, but weak reactions of agglutination are often problematic. Among agglutination reactions, most diffi- cult to interpret is, e.g., a weak Rh-positive result obtained in blood-group- identifications. In such situ¬ ations it is of essential importance to obtain a reliable output, because the safety of the patient is concerned. The objective of the method in accordance with the invention (observation of, e.g., agglutination reactions and reading of the final results) is to be abl to ascertain the difference between agglutination and non-agglutination sufficiently clearly, reproducibly, an carefully. -By mean ' s of the principle of vertical mea¬ surement (Suovaniemi, Osmo, "Performance and Properties the Finnpipette Analyzer System", Proceedings of the Second National Meeting on Biophysics and Biotechnology in Finland, 183, 1-97 * 5) it is possible to measure agglu¬ tination reactions. However, in the case of very, weak agglutinations, one beam of light does not produce a suf ficient difference in absorbance between agglutination a non-agglutination. In the method in accordance with the invention any uncertainty is eliminated by performing the measurement of the properties of the agglutination precipitate at several points once or several times so as to observe the formation of the precipitate as a function of time. The agglutinated precipitate formed on the bottom of the reaction vessel is, viz., structurally different from a non-agglutinated precipitate. The forme is, e.g., unho ogeneous, at the middle part denser than at the sides, whereas the latter is even and relatively homogeneous. 3y performing, e.g., the measurement of absorption of light at several different points of the precipitate obtained, it is possible to distinguish bet¬ ween agglutinated precipitate and non-agglutinated precipitate reliably. The method in accordance with the invention is characterized in that, in order to measure the formation, location, and form of the precipitate and/or the density or other properties of different points of the precipitat a component field of limited area, out of the field of the vessel bottom to be " measured, is measured; the vessel and/or the source of radiation and/or the detector is/are moved so that the component field subject to measurement moves along the field to be measured; and the measurement result of the component field at each particular time under measurement is read constantly or at specified intervals for the purpose of processing and output of the information. The apparatus in accordance with the invention is characterized in that, at one time, either the source of radiation or the detector receiving radiation covers only a limited component field of the bottom of the vessel and that the vessel and/or the source of radiation and/or the detector receiving the radiation can be shifted so that the location of the component field to be measured out of the bottom of the vessel at the bottom of the vessel is changed. For the measurement of the light absorption and/or the transmittance of the precipitate, an either slit-shaped or subtaritially point-shaped source of light is placed underneath the bottom of the reaction vessel, " in its immediate proximity, which source cf light illumi- nates only a little part of the precipitate at a time. When the reaction vessel and the source of light are shifted in relation to each other, the light passes altεrnatingly through different parts of the precipitate, whereby it is possible to measure and to register the light absorption and/or transmittance at each particular point of the precipitate altematingly by means of the detector placed above the reaction vessel. Since ar. agglutinated precipitate gives a line of light absorbance and/or transmittance values different from that given by a non-agglutinated precipitate, it can be decided easily electronically which case is concerned. Some of the features typical of the apparatus based on the method described above are as follows: 1. Therein the principle of vertical measure- , ment is applied, such as in the "FP-9" photometer (U.S. Patent 4,144,030) . 2. The reaction vessel is shifted laterally so that the beam of measurement alternatingly meets differ¬ ent points of the precipitate placed on the bottom of the vessel, or 3. The beam of measurement is shifted laterall so that it meets different points of the precipitate placed in a stationary reaction vessel alternatingly. 4. The movements described in sections 2 and 3 can be performed in more than one directions, whereby, when a point-shaped source of light or detector is used, the topography of the precipitate placed on the bottom of the vessel can be examined completely. 5 . The principles described in sections 1 to 4 can be applied to a multi-channel apparatus, such as, e.g. the "FP-9" photometer. 6. The principles described in sections 1 to 4 can also be applied to apparatuses measuring phenomena other than light absorption or transmittance (fluorometer, luminescence, etc.). The invention will be described in more detail below with reference to the attached drawings, wherein Figures la and lb illustrate two different „_ cases in a reaction vessel, Figure 2 schematically illustrates an alterna¬ tive in which one slit-shaped source of light is used that can be shifted in relation to the reaction vessel. Figure 3 s c:-:s an absorbance curve obtained from the reaction vessel of Fig. 2; underneath the curve, the reaction vessel of Fig. 2 is shown as viewed from the top (in the curves of the figures, the x-axis illustrates the location of the point of measurement on the path of movement and the y-axis illustrates the absorbance at each particular time or in each particular point), Figure 4 shows absorbance curves obtained by means of the source of light shown in Fig. 5 ; underneath the curves the precipitate measured is shown as viewed from above, and Figure 5 is a sche atical presentation of a source of light that consists of several point-shaped sources of light. In Figure la there is a precipitate 4a on the bottom of the reaction vessel 2, the shape and density of the said precipitate being at different points different from those of the precipitate 4b shown in Figure lb. The precipitate 4a illustrates an agglutinated situation, whereas figure 4b represents a non-agglutinated precipi¬ tate in the situation of measurement. Figure 2 schematically shows' a slit-shaped .source of light 1, a reaction vessel 2, and a detector 3- The length of the slit is preferably somewhat less than the diameter of the vessel bottom. On the bottom of the reaction vessel 2 there is a precipitate 4, which has agglutination sections of different types and thicknesses. When, e.g., the reaction vessel 2 passes across the stationary source of light 1 and detector 3 once in the transverse direction of the slit 1 so that the slit-shaped team of light 5 passes, point by point, through the pre- ipitate •-- on the bottom of the reaction vessel 2, the absorbance curve 3 shown in Fig. 3 is obtained, which curve may be continuous or consist of individual points. Figure 3 also shows a top view of the precipitate 4 on the bottom 2 of the reaction vessel. The measurement has been performed by at a time always measuring a stripe of the shape of the slit-shaped source of light out of the precipitate en the c: :;." of the reaction vessel and by producing .the output of the measurement value of this stripe. The production of the output may take place for each stripe separately, whereby a stepwise curve or a curve consisting of individual points is obtained, or as a continuous measurement, whereby the detector measures constantly during the movement and a continuous curve is obtained as the result. Figure 4 shows a precipitate 4 measured from the bottom of the reaction vessel 2 so that the reaction vessel has passed across the sources of light 8 to 10 arranged in a line and shown in Fig. 5, so that measure¬ ment has first been performed by means of the source of light 8 and the other sources of light 9 and 10 have bee closed. Then the reaction vessel has come back, and the the measurement has been performed by means of the beam whereas the beams 8 and 10 have been closed. Finally th beams 8 and 9 have been closed and the measurement has been performed by means of the beam 10, when the reactio vessel has by-passed it. In Figure 4 the beam 10 is cor responded by the scan 13 and by the absorbance curve I β . Correspondingly, the beams 9 and 8 correspond the scans 12 and 11 and the absorbance curves 15 and 14. The reaction vessel moves back and forth at its measurement point a number of times equalling the number of measure- ment beams in operation. It is also natural that one dot-shaped source of light may move along the slit shown in Figure 5 3 being alternatingly in positions 8, 9 and 1 The invention is not confined to the above alternative embodiments only, but it may show even con- siderable variation within the scope of the patent claim It is evident that in the method described above " the source of light and the detector may change places, whereby the detector is placed * immediately undemeath the reaction vessel and it is given a slit- shaped- or dot-shaped form. The method of measurement may be based on photometry or multiphotometry, the latter meaning a photometer which comprises several channels so that _each sample has a source of light and a detector of its own. The method of measurement may, of course, bein a single-channel or multi-channel method, be additionall based, e.g., on turbidometry, fluorometry, or, e.g., on the use of a source of radiation and a receiver for luminescence, laser beam, ultrasound, etc. phenomena. The positioning of the reaction vessels or equivalent, of sources of measurement beams,_ of detector etc. auxiliary equipment may be performed in the way most appropriate in each particular case. The equipment may also involve various degrees of automation, e.g., in the pipetting of the samples and reagents, in the shifting of the beams of measurement, and in the processing of the results. It is natural that, in stead of one method of measurement, the reaction vessels may be measured simul¬ taneously or subsequently by means of two or more wave lengths or methods of measurement (e.g., photometry and fluorometry) , the final result being based on the infor- ation thereby obtained. In.stead of the sources of light arranged in a line, shown in Figure 5 , it is also possible to use one • source of light and, correspondingly, detectors arranged in a line, the said detectors moving in relation to the reaction vessel. The detectors may be in operation either all of them at the same time, in which case one scan movement is adequate, or each of them alternatingly, where¬ by the scanning is performed correspondingly several times. Correspondingly, it is also possible to use one detector that moves along a slit between the scan move¬ ments. Movement of the field of measurement in relation to the bottom of the vessel can be arranged either by shifting the vessel or the dot-shaped or slit-shaped source of light or the detector, or both.

Claims: WHAT IS CLAIMED IS: 1. A method for the measurement of the pro¬ perties of an agglutination, a precipitate (4), or of a corresponding reaction result placed on the bottom of a vessel (2) by means of radiation and of a detector (3) that receives radiation, whereat the beam of measurement (5) coming from the source of radiation (1) passes sub¬ stantially in the direction of the vertical axis of the vessel, and the intensity of the r-adiation passing throug or reflected from, the precipitate on the bottom of the vessel is measured, c h a r a c t e r i z e d in that, in order to measure the formation, location, and form of the precipitate and/or the density or other properties of different points of the precipitate, a component field of limited area, out of the field of the vessel (2) bottom to be measured, is measured; the vessel (2) and/or the source of radiation (1) and/or the detector (3) is/are , moved so that the component field subject to measurement moves along the field to be measured; and the measurement result of the component field at each particular time under measurement is read constantly or at specified 2. A method as claimed in claim 1, c h a r - a c t e r i z e d in that out of the bottom of the vessel relation to the bottom of the vessel in the transverse direction of the stripe. 3- A method as claimed in claim 2, c h a r - a c t e r i z e d in that the production of the output takes place graphically as a continuous or stepwise curve (5), one of the axes (x) in the system of coordinates representing the position of the field to be measured on the bottom of the vessel and the other axis (y) repre- senting the measurement values, e.g. the absorbance. 4. A method as claimed in claim 1, c h a r ¬ a c t e r i z e d in that out of the bottom of the " vessel a dot-shaped field is measured which moves across the bottom of the vessel several times at different points. 5. A method as claimed in claim 1, c h a r - a c t e r i z e d in that out of the bottom of the vessel a line formed by two or more dot-shaped fields is measu¬ red, which line moves across the bottom of the vessel in the transverse direction of the line. β. A method as claimed in claim 4 or , c h a r a c t e r i z e d in that the production of the output takes place graphically as two or more curves (14 to Iβ), one of the axes (x) of the system of coordinates representing the position of the field to be measured on the bottom of the vessel and the other axis (y) repre- senting the measurement values, e.g. the absorbance. 7. An apparatus for the implementation of the method as claimed in claim 1, which apparatus comprises said detectors being located so that the measurement beam received by them passes substantially in the direction of the vertical axis of the vessel, as well as an output unit, c h a r a c t e r i z e d in that, at one time, either the source of radiation (1) or the detector (3) receiving radiation covers only a limited component field of the bottom of the vessel (2) and that the vessel (2) and/or receiving the radiation can be shifted so that the loca¬ tion of the component field to be measured out of the bottom of the vessel at the bottom of the vessel is changed. 8. An apparatus as claimed in claim 7 > c h a r a c t e r i z e d in that the source of radi¬ ation (1) or the detector (3) receiving radiation is a lengthy, narrow slit that' is placed immediately under- neath the bottom of the vessel (2) and that can be shifted in relation to the bottom of the vessel in the transverse direction of the slit 9. An apparatus as claimed in claim 7, c h a r a c t e r i z e d in that the source of radi¬ ation (1) or the detector (3) receiving radiation is dot-shaped and fitted immediately underneath the bottom of the vessel (2) and is movable in relation to the botto of the vessel so that its track of movement parallel to the plane of the bottom covers a part of or the whole of the area of the vessel bottom. 10. An apparatus as claimed in claim 7^ 10 c h a r a c t e r i z e d in that' the source of radi¬ ation (1) or the detector (3) receiving radiation is dot-shaped and that two or more of them are fitted in a line (8 to 10), whereby the said line can be shifted back and forth in relation to the bottom of the vessel (2 15 in the transverse direction of the line and that, when several sources of light are used in a line, each source of light is in operation alternatingly. 11. An apparatus as claimed in any of claims ( to -u c n a a c t e i z e α -n tnat a unit cor-- ----- ;o the appa¬ ratus, whereby the measurement can be performed simul¬ taneously or subsequently out of several vessels. *

Inventors: EKHOLM P, JAERNEFELT J, KAUKANEN E, PARTANEN P, SUOVANIEMI O
Applicants: LABSYSTEMS OY
Application year: 1981
Main classification: G01N21
IPC codes: G01N21