WO1992005422A1

WO1992005422A1 - Specific gravity measurement of liquids

Info

Publication number: WO1992005422A1
Application number: PCT/EP1991/001808
Authority: WO
Inventors: Moh Samir Amer; Jean-Marie Brisset; André Ulmann; Jean-Pierre Delage-Toriel; Jacques Stemer
Original assignee: Moh Samir Amer; Brisset Jean Marie; Ulmann Andre; Delage Toriel Jean Pierre; Jacques Stemer
Priority date: 1990-09-24
Filing date: 1991-09-20
Publication date: 1992-04-02
Also published as: AU8508091A

Abstract

A method of determining the specific gravity of a liquid comprising mixing with such liquid one or more discrete bodies or amounts of solid or liquid testing material immiscible with, and having predetermined specific gravities approximating or different from the specific gravity of, the liquid being tested, each body being preferably visibly distinguishable, as by size, shape and/or color, from each other body with a different specific gravity, and observing which body or bodies float, indicating the specific gravity of the liquid being tested to be above or more than that of the floating body or bodies, and which body or bodies sink or submerge, indicating the specific gravity of the liquid being tested to be below or less than that of the sunken or submerged body or bodies; and a kit or package for carrying out such method containing such body or bodies of testing material, desirably with means for mixing each body or bodies with the liquid, typically urine being tested.

Description

SPECIFIC GRAVITY MEASUREMENT OF LIQUIDS

FIELD OF THE INVENTION

This invention relates to means, including a method and apparatus or kit, for measuring or determining, accurately or approximately, the specific gravity of a liquid,

BACKGROUND OF THE INVENTION

Specific gravity determination is one of the routine medical 'diagnostic tests carried out on several body fluids most notably urine. In the case of urine, high specific gravity can be indicative of susceptibility to kidney stones, while low specific gravity can diagnose inability to concentrate urine which could, underlie other kidney problems.

The specific gravity of urine is inversely related to the urinary output. Maintenance of high urinary output is a therapeutic goal necessary to avoid occurrence of kidney stone disease and/or urinary tract infections. High urinary output reflects sufficient water intake needed to prevent dehydration, a frequent condition in people living in warm climates, frequent airline travelers and in older individuals. Renal stone disease, which is directly related to high urine density, accounts for about 7-10 of every 1000 hospital admissions in the United States.

Normal urinary output varies between 0.25 to 5.0 liters a day depending on the amount of water intake. Urine density can vary accordingly between about 1.001 and 1.030. A urine density of 1.010 - 1.015

corresponds to an average desirable urinary output and water intake of 1-2 liters per day.

In theory, measurement of urinary output is simple. In practice, however, it is very difficult since it necessitates the collection of all the urine excreted during a precise 24 hour period. Thus, it is easier to measure the specific gravity of a urine sample. Another use of frequent urine density (specific gravity) measurements is to monitor the kidney health of those drinking hard water or water with high salt contents. Hard water intake or prolonged drinking of water with high dissolved salts increases the work load of the kidneys and can result in kidney stones. The finding of elevated urine specific gravity in those people necessitates replacing their regular water with low salt or even distilled water to lower the salt concentration and specific gravity of their urine and to reduce their potential for kidney stones and other kidney problems.

Specific gravity determinations are generally

laborious and require the use of expensive and

specialized equipment. The methods now available are not suitable for home use. The determination of urine specific gravity at home is needed to frequently monitor the water intake of patients on certain

treatments or to follow up their conditions and/or the effectiveness of their treatments. Most importantly, specific gravity determinations are needed to monitor daily water intakes in kidney-stone-susceptible

populations. Repeated urinary density measurements are necessary to ensure a permanent and persistent high daily urinary volume and water intake.

OBJECTS OF THE INVENTION

It is an object of this invention to provide an easy, quick, simple and/or inexpensive method of determining the specific gravity of any fluid or liquid, especially urine, in the home or office.

Another object of the invention is to provide such a method to determine whether such fluid or liquid has a specific gravity which is above, below or within acceptable maximum and minimum limits.

Still another object of this invention is the

provision of a suitable apparatus, equipment, device, testing material and/or other means for conducting the aforesaid methods.

Other objects and advantages will appear as the description proceeds.

SUMMARY OF THE INVENTION

According to certain of its aspects, the attainment of one or more of the above objects is made possibLe by this invention which at least in part typically

comprises mixing with the fluid or liquid (e.g. urine) being tested one or more discrete bodies or amounts of testing material of predetermined specific gravity and immiscible with such fluid or liquid and observing whether such testing material floats, indicating the specific gravity of the liquid to be above (more or higher than) that of the testing material, or sinks, indicating the specific gravity of the liquid to be below (less or lower than) that of the testing

material. If a testing body remains submerged below the surface and above the bottom of the liquid being tested, the specific gravities of the testing body and liquid being tested can be considered to be

substantially the same.

According to a further embodiment of this invention, the method employs a first such body with a specific gravity below, and another such body with a specific gravity above, the expected or normal specific gravity of such liquid being tested.

According to a still further embodiment of this invention, the method employs at least 2 such bodies with specific gravities different from each other and above, and at least 2 such bodies with specific

gravities different from each other and below, the expected or normal specific gravity of the liquid being tested.

According to another feature of the invention, an apparatus, equipment, testing material or kit for conducting the methods of this invention is provided comprising discrete, separate bodies of testing

material immiscible with the liquid being tested, one such body having a specific gravity above, and another such body having a specific gravity below, the expected or normal specific gravity of the liquid being tested.

If desired, for a more accurate measurement or a greater range of possible specific gravities, the kit may contain a plurality of bodies, at least 2 with specific gravities different from each other and above, and at least 2 with specific gravities different from each other and below, the expected or normal specific gravity of the liquid being tested.

Preferably, each body is visibly different or

distinguishable from each other body with a different specific gravity; as by being colored, sized or shaped differently. The bodies employed in the methods ofthis invention may be liquid, e.g. drops or droplets, or solid, e.g. bodies of silicon, inorganic or organic plastic, or polymeric material or the like.

DETAILED DESCRIPTION OF THE INVENTION

As indicated above, the testing material may be a solid or liquid immiscible with the liquid being tested. Bodies of solid material may comprise any type of natural or synthetic material, wood, natural gums such as rosin, and desirably plastics which can by known means be prepared with any desired predetermined specific gravity. The testing material may be natural or synthetic, organic or inorganic, thermosetting or thermoplastic, resins or polymers such as ABS

(acrylonitrile/butadiene/styrene), nylons,

polyetherimides, polyolefins such as polyethylene and polypropylene and their copolymers and alloys, ethylene vinyl acetate copolymers, polystyrenes, SAN copolymers, polycarbonates, SKA polycarbonate alloys, polyesters, thermoplastic elastomers of various types, polyurethanes, urea-, phenol- and melamine-formaldehyde resins, εiliσones, and other plastics.

Solid bodies of testing material may be in any desired size, shape or color, e.g., beads, pellets, spheres, cubes, flakes, discs, pyramids, stars, round, square, or triangular rod sections, etc., of any convenient size suitable for floating or suspending in the amount of liquid available for testing, and of course large enough to be easily visible in the liquid being tested but not so large as to interfere with each other during testing or as to require a larger amount of liquid being tested than available for such testing. Typically, the smallest dimension would be about 0.1 inch and the largest dimension could be about 1 inch. Of course, if a large amount of the liquid being tested is available, as in a barrel, tank, reservoir or the like, the largest dimension could be much larger than 1 inch and as high as suitable, convenient or desired. The bodies could have solid colors, or be variegated, marbleized, striated, or with other patterns,

decorations or intelligence providing insignia using any suitable pigments or other coloring material. For convenience in describing this invention, solid bodies of testing material will be referred to hereafter as beads, and the liquid to be tested as urine.

Beads of plastic solid testing material are

preferred. For example, beads of plastic material with the same or lower specific gravity could be used, and beads with increasing predetermined specific gravities prepared by addition of suitable proportions of

increasingly heavier filler material to the melted or fluidized plastic. Many types of such fillers may be employed, for example silica, sand, salts of barium, lead, tin, copper, iron and the like. Increasing amounts of the same filler may be employed to make beads of increasing specific gravities.

Another method of preparing plastic beads with different specific gravities involves simply mixing 2 or more plastic polymeric materials of significantly different known specific gravities in predetermined proportions calculated to provide any specific gravity between the highest and lowest of the plastics being mixed.

If it is only desired to determine whether the specific gravity of the urine is too high or too low, only a single bead need be used with a preset specific gravity at the upper or lower acceptable limit. For example, if the urine is suspected of having a specific gravity above 1.013, a bead with that specific gravity would be added to the urine. If it floats, the urine has a specific gravity above 1.013. If it sinks, the urine specific gravity is below 1.013, Similarly, a bead with a specific gravity of 1.001 sinking in urine would indicate a urine specific gravity below 1.001.

It is preferred however to provide the patient or other testing person with an assemblage, kit, package or the like with at least two or more, preferably 3 or 4, still more preferably 5 or more beads, each with different specific gravities ranging from the lowest to the highest expected, which for urine would be between about 1.005 and about 1.025. The beads need not actually be visibly different, in which case the specific gravity of the urine would be determined from the number of beads floating and/or sinking. For example, if the kit contains 5 beads ranging in

specific gravity from 1.005 to 1.025 in increments of 0.005, and all float in the urine, it indicates a specific gravity above 1.025. If only one floats, it would be the 1.005 bead, indicating a urine specific gravity between 1.005 and 1.010. If 2, 3 or 4 float, it indicates a urine specific gravity from,

respectively, 1.010 to 1.015, 1,015 to 1.020, and 1.020 to 1.025. If all sink, the urine specific gravity is below 1.005. Preferably, the beads in the kit have different shapes and/or colors for each specific gravity. A convenient form of kit or package comprises a pipette or ordinary kitchen baster with a flexible transparent bulb containing the 5 or so beads with increasing specific gravities as above described. The pipette or baster tube, with the bulb squeezed, is inserted in the container of urine being tested and the bulb pressure released to suck up sufficient urine to float at least one of the beads (e.g. half-way up the bulb), and observing the number and/or identity of the beads which float or remain submerged.

Instead of solid beads, the testing material may be comprised in bodies, e.g. drops or droplets of urine- immiscible liquids having the same range of specific gravities as the above-discussed beads. The kit or package supplied for this purpose, for example, may comprise 5 bottles, vials or other containers with droppers, each bottle containing a body of urine- immiscible liquid with different specific gravity and preferably differently colored from each other. Drops from any or all of the bottles may be deposited in the container of urine being tested and observing which drops float or sink.

Many types of liquids immiscible in the liquid being tested are known and readily available. Non-limiting examples include benzonitrile, benzene, cyclopentane, oils, silicones and the like. Examples of colors soluble or dispersible in the testing liquid include, without limitation, diacetyl amino azotoluene,

azonaphthol, other azo dyes, and the like. The drops of testing liquid in the urine or other liquid being tested are not readily recoverable and are discarded with the urine in contrast to the solid beads which are readily recovered by filtration, decantation, etc.

The following examples are illustrative of this invention and are not to be regarded as limitative. all amounts and proportions referred to herein and in the appended claims are by weight unless otherwise indicated. Example 1

Preparation of Plastic Beads

A. Poly (lauryl methacrylate), specific gravity 0.929

B. Poly (methyl methacrylate), specific gravity 1.188

In a heatable container we mix 68 gm. of A with 32 gm. of B. Heat and stir under vacuum until completely mixed. Allow to cool. Extrude or cast into the desired shape.

Plastic Sp. Gr. % Contribution to

Final So. Gr.

A 0.929 X 68 = 0.632

B 1.188 X 32 = 0.380

1.012

Thus, the final mix will have a εp. gr. of 1.012. The use of vacuum is necessary to prevent the inclusion of a variable amount of air with unpredictable effects on the final specific gravity. Different properties of A and B are employed to produce plastic beads with other desired specific gravities.

Example 2

Five plastic beads are prepared as follows:

Bead Soecific Gravity Shape

1 1.005 tube

2 1.010 ball

3 1.015 disc

4 1.020 plate (0.5" sq x

0.1" thick)

5 1.025 rod

All 5 beads are added to the urine being tested. Floating of all beads indicates a high specific gravity urine (above 1.025) which may result from low water intake and cause kidney stones. Sinking of beads 1 and 2 establishes a specific gravity between 1.010 and 1.015 which may indicate normal kidney function and sufficient water intake. Sinking of all beads

establishes a urine specific gravity below 1.005, indicative of inability to concentrate urine and possibility of existence of other types of kidney disease.

Example 3

Preparation of Liquid Testing Material

A. Cyclohexane, specific gravity 0.7781

B. Carbon tetrachloride, specific gravity 1.589 Mix 71 gm. of A with 29 gm. of B. Add a slight amount of oil soluble color.

Plastic Sp. Gr. % Contribution to

Final Sp. Gr.

A 0.7781 x 71 0.552

B 1.589 X 29 = 0.461

Final Specific Gravity 1.013

Different proportions of A and B are employed co produce liquid testing material with other desired specific gravities.

Example 4

Five liquids are prepared ranging in specific gravity from 1.005 to 1.025 as in Example 2, and colored differently from each other so as to be visibly

distinguishable. One or two drops of each liquid are added to the urine being tested, observing which drops float or sink, and thereby determining the specific gravity of the urine in the same manner as described with respect to plastic beads as in Example 2. Example 5

Clinical Test

Six patients with a propensity for kidney stone formation were tested for urine density or specific gravity using three plastic beads with slightly varying densities approximating 1.013 according to the

invention and using a conventional laboratory method (CLM) for comparison. After preliminary testing of their urine densities (Pre), they were asked to drink 1 liter of water and were then later retested (Aft). The number of beads that floated (F) and the number that sank (S) in each test were counted. Results were as follows:

Pre Aft

Patient Beads CLM Beads CLM

1 3F 1.040 3S 1.010

2 3S 1.010 3S 1.005

3 3F 1.030 3S 1.010

4 3F 1.030 3S 1,010

5 3S 1.010 - - --

6 1F, 2S 1.015 - - --

These results demonstrate the operativeness and reliability of this invention and its clear clinical

.utility.

This invention has been described with respect to certain embodiments and it will be understood that modifications and variations thereof obvious to those skilled in the art are to be included within the spirit and purview of the invention (and disclosure) and the scope of the appended claims.

Claims

WE CLAIM:

1. A method of determining the specific gravity of a liquid comprising mixing with such liquid one or more discrete bodies or amounts of testing material of predetermined specific gravity and immiscible with such liquid and observing whether the testing material floats, indicating the specific gravity of the liquid to be above that of the testing material, or sinks, indicating the specific gravity of the liquid to be below that of the testing material.

2. A method according to Claim 1 wherein said testing material comprises a first body with a specific gravity below, and another body with a specific gravity above, the expected or normal specific gravity of the liquid.

3. A method according to Claim 2 wherein said bodies are visibly distinguishable from each other.

4. A method according to Claim 3 wherein said bodies are colored differently from each other.

5. A method according to Claim 4 wherein said bodies are liquid immiscible with the liquid being tested.

6. A method according to Claim 4 wherein said bodies comprise solid plastic material.

7. A method according to Claim 3 wherein said bodies comprise solid plastic material.

8. A method according to Claim 7 wherein said bodies are sized or shaped differently from each other.

9, A method according to Claim 2 wherein said testing material comprises a plurality of bodies, at least two with specific gravities different from each other and above, and at least two with specific

gravities different from each other and below, the expected or normal specific gravity of the liquid being tested,

10. A method according to Claim 9 wherein each body is visibly distinguishable from each other body with a different specific gravity.

11. A method according to Claim 10 wherein each body is colored differently from each other body with a different specific gravity.

12. A method according to Claim 11 wherein said bodies are liquid immiscible with the liquid being tested.

13. A method according to Claim 11 wherein said bodies comprise solid plastic material.

14. A method according to Claim 10 wherein said bodies comprise solid plastic material,

15. A method according to Claim 14 wherein each body is sized or shaped differently from each other body with a different specific gravity.

16. A method according to Claim 1 wherein the liquid being tested is urine.

17. A method according to Claim 2 wherein the liquid being tested is urine.

18. A method according to Claim 5 wherein the liquid being tested Is urine.

19. A method according to Claim 6 wherein the liquid being tested is urine.

20. A method according to Claim 8 wherein the liquid being tested is urine.

21. A method according to Claim 9 wherein the liquid being tested is urine.

22. A method according to Claim 12 wherein the liquid being tested is urine.

23. A metnod according to Claim 13 wherein the liquid being tested is urine.

24. A method according to Claim 15 wherein the liquid being tested is urine.

25. A package for determining the specific gravity of a liquid comprising discrete separate bodies of testing material immiscible with such liquid, one such body having a specific gravity above, and another such body having a specific gravity below, the expected normal specific gravity of said liquid.

26. A package according to Claim 25 wherein each such body is visibly distinguishable from the other such body.

27. A package according to Claim 26 wherein said such bodies are colored differently from each other.

28. A package according to Claim 27 wherein said bodies are liquid.

29. A package according to Claim 27 wherein said bodies comprise solid plastic material.

30. A package according to Claim 26 wherein said bodies comprise solid plastic material.

31. A package according to Claim 30 wherein said bodies are colored or shaped differently from each other.

32, A package according to Claim 25 comprising a plurality of such bodies, at least two with specific gravities different from each other and above, and at least two with specific gravities different from each other and below, the expected or normal specific gravity of the liquid being tested.

33. A package according to Claim 32 wherein each body is visibly distinguishable from each other body with a different specific gravity.

34. A package according to Claim 33 wherein each body is colored differently from each other body with a different specific gravity.

35. A package according to Claim 34 wherein said bodies are liquid.

36. A package according to Claim 34 wherein said bodies comprise solid plastic material.

37. A package according to Claim 33 wherein said bodies comprise solid plastic material.

38. A package according to Claim 37 wherein each body is sized or shaped differently from each other body with a different specific gravity.