Method and apparatus for dispensing liquids

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TECHNICAL FIELD

The present invention relates generally to dispensing methods and apparatus and more specifically to methods and apparatus for separating, filtering and dispensing liquids such as blood serum, saline-washed red blood cells, and other biological fluids.

BACKGROUND OF THE INVENTION

The separation and analysis of chemical substances provides valuable quantitative and qualitative data for use by researchers and health care providers. Many assaying techniques have been deviced which utilize sensitive chemical and instrument tests to detect both normal and abnormal components of biological fluids. In particular, the analysis of blood samples yields information which is critical to the proper diagnosis and treatment of many illnesses. To perform a blood test, a sample is obtained and then prepared for analysis by one of the many analytical procedures currently available. The preparation of the sample typically requires that the various sample components be separated in order to obtain a more nearly homogeneous specimen for testing, such as isolating blood serum which is then dispensed for analysis. The amount of serum protein, proteinbound iodine, sodium, triglycerides, salicylate, uric acid and the like can all be determined through the separation and analysis of blood components. Hence, fast and accurate methods for preparing and dispensing samples for analysis are highly desirable.

The task of conveniently and efficiently dispensing a liquid, such as a biological fluid, from a container such as a test tube is encountered routinely by lab workers in a variety of circumstances. The mouth of a test tube must be large enough for material to be readily added to the tube chamber; however, this feature makes it difficult to dispense fluid from the test tube. Conventional dispensing techniques are only marginally effective in many applications. For example, decanting a liquid from a precipitate using a stirring rod requires considerable manipulative skill and fails to provide adequate control over the volume of liquid to be dispensed. Similarly, while providing a lip or spout on a container may help direct the flow of fluid somewhat, volume control is still not attained and splashing often occurs. The transfer of liquids is more accurately controlled with a dropper pipet; however, this requires that a pipet be provided and that the pipetting operation be preformed each time a liquid sample is dispensed.

Particularly in the environment of processing and dispensing biological fluids, a simple and convenient method and apparatus are needed so that a fluid can be easily dispensed from a container such as a test tube. The present invention provides such a method and apparatus whereby virtually any liquid can be easily dispensed without the use of complicated pouring techniques and devices.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided an elongate, hollow, resilient dispensing device adapted to be engaged on the open end of a test tube or other similar container. The hollow dispensing device includes a resilient tube having a broad opening at one end and a nipple at the other end. A filter may also be provided within the resilient tube such that fluid passing through the dispensing device passes through the filter. In the metod of the present invention, the resilient dispensing tube is attached to the mouth of a container such as a test tube containing a liquid sample so that the dispensing tube is frictionally engaged by the container wall in a concentric manner to form a seal. The nipple end extends out beyond the open end of the container as does a substantial portion of the resilient dispensing tube. The container and attached sampling tube are then inverted so that the liquid to be dispensed flows into the resilient sampling tube. If a filter is provided, the liquid flows through the filter to remove any unwanted components such as gel. By squeezing the sides of the resilient sampling tube, one or more drops of fluid can be accurately dispensed through the nipple. A cup is also provided which prevents evaporation or leakage of the sample through the nipple opening.

The present invention further provides both a method by which a stratified layer of filtrate can be isolated and conveniently dispensed from a sampling apparatus, and a sampling apparatus which can be used to separate and dispense a filtrate at a controlled rate. Hence, the present invention is adapted to be attached to a conventional sampling container apparatus for dispensing a precise quantity of liquid at a controlled rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side-elevational view of the present invention with a partially threaded resilient dispensing member closely