Chemistry: analytical and immunological testing – Optical result – With claimed manipulation of container to effect reaction or...
Reexamination Certificate
1999-03-30
2001-08-21
Alexander, Lyle A. (Department: 1743)
Chemistry: analytical and immunological testing
Optical result
With claimed manipulation of container to effect reaction or...
C422S051000, C422S067000, C436S168000
Reexamination Certificate
active
06277647
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates to a method and an apparatus for developing a test strip, and more particularly a test strip having a reagent test pad requiring an incubation period for developing the desired test results disposed thereon.
2. Description of the Related Art.
Test strips having a reagent test pad disposed thereon are conventionally known testing devices which are often used to determine whether a sufficient concentration of a chemical or chemicals is present in a solution. In the conventionally known procedure, the reagent test pad having reagent chemicals disposed thereon is placed in contact with a solution to be tested, typically by dipping the test strip in the solution. When the reagent test pad is sufficiently wetted, the test pad is removed from the solution and the indication on the test pad is examined after a predetermined waiting time. The reagent test pad is usually designed to change to a particular color or range of colors corresponding to the concentration of the chemicals in the solution being examined. In conventionally known procedures, the user places the wetted test pad in an open environment, such as on a lab bench, while waiting for the color change to develop.
Although simple to use, one consideration in using such test strips is the accuracy and reliability of the color indications developed on the reagent test pads. In conventional applications, a standardized chart showing various colors and corresponding concentrations is provided. To be effective and reliable, the test performed should always produce a color which corresponds to an accurate concentration of the chemical being tested. In other words, the person performing the test should be able to confidently match the color produced by the test strip with a corresponding color on the standardized chart and the concentration of chemical then taken therefrom.
Unfortunately, due to the imprecision inherent in any analytical tests, the desired indication may be observed at concentrations other than the predetermined concentration. For example, in a test producing a mere change in color at a given concentration, such color change could incorrectly occur at a concentration other than the given concentration. The concentration at which the test always reads “PASS” or “FAIL” is determined by the properties and conditions of the test. The difference in the 100% FAIL and the 100% PASS concentration may be called the “window”. It is desirable to have the range of this window be as small as possible to ensure effective management and use of the solutions being tested, for example to ensure that only effective solutions are used and to ensure that effective solutions are not needlessly replaced.
The window may be narrowed in many tests by increasing the reaction time between the chemicals in the reagent test pad and the chemicals in the solution. This is most likely due to two factors associated with dry reagents tests, namely 1) the reactants on the test strip need time to completely dissolve, and 2) the diffusion of reactants in a solid matrix is very slow. However, because these reactions occur in aqueous solutions, the reaction time available for the test is limited by the evaporation of water from the reagent test pad. Accurate measurement within a narrow window is difficult if the moisture necessary to maintain the reagents in solution evaporates from the reagent test pad before the reaction is complete. This is particularly true when measuring highly concentrated analytes where the loss of even small amounts of water may cause precipitation of analytes and/or reactants within the test pad.
Conventionally known methods and apparatuses are limited in their ability to obtain accurate and reliable results within a narrow window because the water necessary to maintain the reagents in solution typically evaporates from the test pad before allowing a sufficient incubation period. This evaporation leads to improper use of ineffective solutions as well as wasteful replacement of effective solutions.
Therefore, what is needed is an accurate and reliable method and apparatus for using test strips described above wherein a sufficient incubation period is provided to allow the reagents to completely react with one another before the requisite moisture evaporates from the test pad.
SUMMARY OF THE INVENTION
The present invention is a method and an apparatus for providing accurate and reliable results from a test strip having a reagent test pad disposed thereon when the reagent test pad requires an incubation period for the reagents to react. The present invention also provides a more narrow window between PASS and FAIL indications which in turn allows effective use and management of the test solutions. The present invention achieves these results by placing and maintaining the reagent test pad in an enclosed, high humidity environment, in a substantially vertical orientation during the incubation period.
The method of the present invention comprises, in one form thereof, the steps of providing a test strip having a reagent test pad disposed on one end and a grip portion disposed on another end. The reagent test pad is wetted with a desired test material and placed in an enclosed chamber and after a predetermined waiting period, the results indicated on the reagent test pad are read. The enclosed chamber is advantageously adapted to provide a high humidity environment and the reagent test pad is advantageously maintained in a vertical manner in the enclosed chamber during the incubation period.
In another form, the present invention comprises a test strip holder of reagent test strips having a reagent test pad requiring an incubation period comprising a base and a cover, the base and cover adapted to fittingly engage each other to form an enclosed reaction chamber. The enclosed reaction chamber is adapted to store the reagent test pad. One of the base and cover includes a holding portion adapted to engage the test strip to thereby securely maintain the reagent test pad in the reaction chamber. One of the first and second holders includes a substantially clear portion allowing viewing of the test strip.
The present invention also comprises, in another form thereof, a combination comprising a test strip having a reagent test pad disposed thereon, the reagent test pad requiring an incubation period, and a test strip holder, the test strip holder comprising a base and a cover. The base and cover are adapted to fittingly engage each other to form an enclosed reaction chamber. The enclosed reaction chamber is adapted to receive and hold the reagent test pad and one of the base and cover includes a substantially clear portion allowing viewing of the reagent test pad.
Additionally, a test strip storage device may advantageously be provided for use with the test strip holder of the present invention wherein the test strip storage device includes a storage element disposed on a pedestal, the storage element having a plurality of recesses formed on a top surface thereof for placement of the test strip holders therein in a manner which allows the user to easily store the test strip holder and view the indication on the reagent test pad.
Therefore, it is an objective of the present invention to provide a method and an apparatus for accurately checking the concentration of a chemical in a solution using a test strip reagent pad.
It is also an objective of the present invention to provide a method and an apparatus for accurately checking the concentration of a chemical in a solution using a test strip pad having a reagent test pad which requires an incubation period.
It is also an objective of the present invention to provide a method and an apparatus which permits a reagent test pad to be vertically stored in a high humidity environment for a sufficient period of time to allow the reactants to fully react.
It is also an objective of the present invention to provide a method and an apparatus which allows a very narrow window between the 100% FAIL and the 100% PASS in
Christner James E.
Price Kenneth W.
Alexander Lyle A.
Baker & Daniels
Serim Research Corp.
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