Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Calorimeter
Patent
1993-07-06
1996-07-16
Alexander, Lyle A.
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Calorimeter
422 61, 436166, 436169, G01N 3349
Patent
active
055364705
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a test field for a test carrier for the determination of an analyte from whole blood with the aid of a reagent system contained in the test carrier, said reagent system comprising a colour formation reagent, with a test field which has a sample application side, to which the blood sample is fed, and a detection side on which, as a result of reaction of the analyte with the reagent system, an optically detectable change occurs, the test field being designed so that erythrocytes contained in the sample do not gain access to the detection side.
2. Description of the Related Art
For the qualitative or quantitative analytical determination of constituents of blood, so-called carrier-bound tests are increasingly being used. In these, a reagent system is embedded in at least one test field of a solid test carrier, said test field consisting of a single layer or a plurality of layers, said test carrier being brought into contact with the sample. The reaction of sample and reagent system gives rise to an optically detectable change, in particular to a colour change which can be evaluated visually or with the aid of an instrument, usually by reflection photometry. Instead of leading to a colour change, the reaction may also give rise to the occurrence of, or to a change in, some other optically detectable signal, for example, fluorescence or luminescence.
Test carriers (which in the English-language literature are frequently also called "solid reagent analysis elements") are often designed as test strips, which essentially consist of a longitudinal carrier layer made of a plastic material, and a single test field or a plurality of test fields applied to it. However, test carriers are also known in which, analogously to a photographic slide, a test field is surrounded by a plastic frame.
Carrier-bound tests are characterised in particular in that they are easy to use. It is all the more unfortunate that, in the majority of test carriers known to date, the blood cannot be used directly as whole blood. Rather, it is necessary to separate the red blood corpuscles (erythrocytes) in order to obtain colourless plasma or serum. This is usually done by centrifuging. However, this involves an additional operation requiring a relatively large amount of blood and expensive equipment.
Many attempts have therefore been made to provide test carriers which permit analytical determinations to be made directly from blood. One can distinguish two fundamentally different possible solutions.
In the first attempted solution, evaluation of the colour change visually or with the use of equipment takes place on the same side of the test field as that to which the sample is applied. In this arrangement, the test field is constructed so that the analyte from the sample penetrates to the reagents through the test field surface, whereas the erythrocytes are retained. After a defined time, the blood sample is wiped or washed from the test field surface and the colour change is observed. Examples of such test carriers are described in U.S. Pat. No. 3,630,957 and in EP-B-130 335 and EP-A-0 217 246.
In the second attempted solution, the sample is applied to one side of the test field (sample application side), and the colour change on the other side (detection side) is recorded.
A major advantage of this method of detection is that the blood need not be wiped or washed off. For this reason, these test carriers are also called non-wipe ("NW")-test carriers.
With the wiping operation there is eliminated not only a tedious operation, but also a possible source of error which may result from imprecise observance of the point in time at which the blood must be removed. However, this attempted solution is especially difficult to embody. An erythrocyte or blood pigment filter is required which on the one hand reliably retains the intensely colouring constituents of blood but on the other hand allows the analyte to pass through completely and sufficiently rapidly. It is proving
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Frey Gunter
Horn Doris
Alexander Lyle A.
Boehringer Mannheim GmbH
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