Chemistry: analytical and immunological testing – Composition for standardization – calibration – simulation,...
Patent
1993-08-20
1995-10-03
Snay, Jeffrey R.
Chemistry: analytical and immunological testing
Composition for standardization, calibration, simulation,...
436171, 73 1R, 73 6148, G01N 2135
Patent
active
054551773
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method and an instrument for the analysis of a medical sample, particularly a body fluid such as blood or urine.
The analysis is performed with the aid of reagents, enzymatic and immunochemical reagents being especially important. For the determination of a specific component of a body fluid (usually called a "parameter"), a specific set of reagents (such as, for example, enzymes, indicators or antibodies) and auxiliary materials (such as, for example, buffers, wetting agents and the like) are required, which are together called a reagent system for the determination of the particular parameter. The reagents are mixed with an aliquot part of the sample synchronously or in a plurality of stages one after the other, and incubated in order to allow the analytical reaction to occur.
At the end of the reaction a physically detectable change takes place, which is measured as a measurable variable that is characteristic of the sought-after concentration of the analyte. In most cases this is a colour change, which can be measured quantitatively with the aid of a photometer. However, other optical (e.g. nephelometric and fluorimetric) and non-optical (e.g. electrochemical) test principles are also used. The invention relates in particular to analyses in which the physically detectable change is measured by optical means, but is basically also suitable for other test principles.
The reactions which occur during these clinicochemical tests must in most cases take place at exactly pre-determined temperatures, the requisite temperature stability and accuracy frequently being given as plus/minus 0.1.degree. C. Maintaining and controlling the temperature of test fluids in the reaction vessels of analysing instruments is therefore a problem with which those skilled in the art have long been occupied.
In many cases the reaction vessels are transported through the analysing instrument in a thermostatically controlled water bath. The good heat transfer associated with this gives rise to the fact that the reference temperature in the reagent vessels is reached relatively rapidly and is held satisfactorily constant. However, this solution to the problem is very expensive from the design point of view.
In the majority of analysing instruments, maintaining the desired temperature is therefore attempted using solid or gaseous media. In widespread use are designs in which the reaction vessels are located in recesses of rotors or transport magazines (so-called "racks"), the rotor or the rack being held at a defined temperature with the aid of temperature-measuring elements and heating devices, and the aim being to ensure the best possible heat transfer by accurate adjustment of the fit of the reaction vessel in the rotor or rack. However, this presupposes that the temperature of the reaction vessels is uniformly influenced by their temperature stabilisation in all positions of the rotor or rack. Practical experience shows that unavoidable temperature gradients lead to considerable differences between the actual temperature in the reaction vessel and the reference temperature. Similar problems also exist in the case of systems in which the reaction vessels are bathed in temperature-stabilised air.
In another known analysing instrument, the problem of unavoidable temperature gradients between the air surrounding the reaction vessels and the reaction vessels themselves is prevented in that a liquid crystal film is disposed on the wall of the reaction vessel and irradiated by a light source. The change in the reflected light as a function of temperature is detected and permits good accuracy of the temperature determination. The application of liquid crystals substantially increases the cost of the reaction vessels, which are in most cases single-use disposable plastic vessels. If the liquid crystal layer is applied on the outside, there remains a temperature gradient through the thermally relatively well insulating plastic wall of the reaction vessel to the fluid in its interior. If the liquid crystal is appl
REFERENCES:
patent: 3776635 (1973-12-01), Haskell
patent: 4224405 (1980-09-01), Hijikata
patent: 4660151 (1987-04-01), Chipman et al.
patent: 5068536 (1991-11-01), Rosenthal
Gfrorer Andreas
Krause Friedemann
Boehringer Mannheim GmbH
Snay Jeffrey R.
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