US 3534851 A
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3,534,851 URINE PRESERVATION PACKAGE John I. Peterson, Falls Church, Va., and Donald S. Young, Rockville, Md., assignors to the United States of America as represented by the Secretary of the Department of Health, Education, and Welfare No Drawing. Filed Mar. 18, 1968, Ser. No. 714,041 Int. Cl. B65d 83/00, 85/70, 85/82 US. Cl. 206.5 8 Claims ABSTRACT OF THE DISCLOSURE A package for the containment of an acidifying material, used in the preservation of urine samples, is pro vided by containing the acidifying material, preferably a solid acid such as sulfamic acid, in a water soluble package made of a material such as methylcellulose. The package is included in a container for a urine sample which is dispensed for patient use, there being no danger to the patient due to the exposure of acid.
The present invention relates to the preservation of urine samples for analysis and more particularly, to the provision of a safety package containing a urine preservative acid.
The preservation of urine samples for analysis has commonly been accomplished by the addition of an acidifying agent to the urine sample. In hospital and other clinical practice, it is convenient and economical to prepare packages, consisting of a bottle or other container, for collecting the urine sample, in which the preservative agent is contained. In such a case the already prepared package is given to the patient for his use. This procedure has been advantageous in the past where the a preservative is not dangerous. In the case of strong acid preservatives, i.e., those with a pK of about three or under, this practice is impractical because of the danger of accidental exposure of patients or other personnel to the acid in the package, in concentrated form, before it has been diluted by urine.
Boric acid, a relatively weak acid, has been used extensively as a urine preservative, primarily because it has superior and unique bacteriostatic properties in comparison with most other weak acids. It is a highly acceptable preservative when one is concerned only with preventing bacterial degradation of the urine sample. However, for most modern purposes of urine analysis, a strong acid of pK not substantially greater than three is necessary, since only such strong acids are capable of bringing the pH of the urine sample down to a level which, in addition to maintaining the urine bacteria-free will keep the magnesium and calcium phosphates soluble and aid in preventing degradation of steroids of analytical interest. The weak acids, including boric acid, cannot reduce the pH of the urine to a sufficiently low level to reliably inhibit steroid degradation and maintain the phosphates dissolved.
It is, accordingly, an object of the present invention to obviate the deficiencies of the prior art, such as indicated above.
It is another object of the present invention to provide for the safe and effective preservation of urine samples utilizing strong acid as the preservative.
It is another object of the present invention to provide a safe container for the collecting of urine samples, which container has therein a strong acid preservative, but which container obviates the danger of accidental exposure of the acid to patients or other personnel.
It is another object of the present invention to provide a package for safely containing a strong acid in concentrated form, which package prevents the exposure of patients or other personnel to the acid, but which package does not inhibit the function of the acid in the preservation of urine samples.
These and other objects, as well as the nature and advantages of the present invention, will be more apparent from the following detailed description, it being understood that the invention is not limited to what is described.
In general, the strongly acidifying material desired to be used for the preservation of the urine sample is placed in a water soluble package and such package is placed in the urine container before use.
More specifically, the strong acid preservative is preferably a solid, under ambient conditions. The water soluble package is preferably a heat sealable polymer film formed into an envelope into which the preferably solid strong acid is placed, in predetermined amounts, the water soluble envelope then being sealed about the acidifying agent. The package is then included in hte urine container, which is dispensed for patient use. Addition of urine to the container causes dissolution of the water soluble package, thereby releasing and dissolving the preservative acid into the urine. Until the urine is collected in the container, the preservative acid is maintained in the stable form, enclosed in the package so that it cannot come into accidental contatc with persons through spillage or other misuse of the container.
While the strong acid preservative agent may be any water-free acid having a pK of lower than about 3, it will be understood that certain types of acids are preferred. Thus, while liquid water-free strong acids may be used, it is preferred that the acid exists under normal conditions as a crystalline solid, preferably without any water of hydration. It is not always essential that the solid acid be anhydrous, since those solid acids which have tightly bound water of hydration may be successfully sealed in the water soluble package. The quantity of acid used is not critical so long as there is suflicient acid present to lower the urine pH to the desired level. A quantity of about 5 to about 20 grams of pure acid provides an optimum range.
The preferred solid crystalline acid preservatives are sulfamic acid, oxallic acid, phthalic acid, maleic acid and benzene sulfonic acid. Citric acid, with a pK of 3.08 for its first ionization may also be used, but it should be understood that acids become less desirable as their pKs become increasingly greater above the value of 2. Acids which are too weak for the type of preservation intended include benzoic, formic and naphthol. It is also not desirable to use certain acids which may adversely affect the type of analysis of the urine contemplated, such as those acids containing the chloride ion; thus, trichloroacetic acid, which would otherwise be expected to be a useful acid in accordance with the present invention, is not generally useful because it will adversely affect the urine analysis.
To summarize, those strong acids which may be selected for use should not contain free-water, should not contain ions which will adversely affect the urine analysis, and should preferably be solid, although liquid acids which will not dissolve the packaging film may also be used. Such acids which have a pK of less than about 3, and preferably of less than 2, can be selected from a listing of acids, such as those listed under Dissociation Constants of Organic Acids in Aqueous Solutions in the Handbook of Chemistry and Physics.
Along with the strong acid preservative may optionally be added other ingredients including preservative-bactericides such as boric acid, formaldehyde and thymol, or anti-oxidants such as tannic acid or hydroquinone. Such additive materials, if used, should preferably be used in a minor proportion in comparison with the strong acid preservative.
The water soluble package is formed of any heat-sealable, water-soluble polymer film. Suitable water soluble polymers are known and have been conventionally used for the packaging of powdered bleach and soap. Included among suitable polymers are the various polyvinylalcohols, including ethoxylated polyvinyl alcohol; the watersoluble alkyl-celluloses such as methylcellulose; the hydroxy alkylcelluloses such as hydroxymethylcellulose and hydroxyethylcellulose; the carboxy alkyl celluloses such as carboxyethylcellulose and carboxymethylcellulose; polymers of ethylene oxide such as polyethylenoxide; gelatin; various types of starch; and other film forming, water-soluble materials, such as the N-alkoxy methyl polypyrrolidones, carboxy methyl dextran, and sodium cellulose sulphate. Other useful water-soluble plastic films are also known. Films of such materials are formed into packaging envelopes, a quantity of to grams of the acid preservative are charged to the envelope and the envelope is then heat-sealed. In this form the packages may be distributed to hospitals, clinics, physicians, etc. for their placement in suitable bottles and distribution to patients. If desired, the packaging film can be imprinted with suitable warning indicia, such as danger or do not rupture or perforate this package.
The following specific example is illustrative of a specific embodiment of the invention, it being understood that such example is not intended as a limitation of the invention.
A commercial polyvinyl alcohol film is formed into an envelope by heat-sealing the edges of the film together and a charge of 10 grams of sulfamic acid is placed in the envelope. The envelope is then heat-sealed closed. The package may be handled without any danger of contact with the sulfamic acid. The polyvinyl alcohol film packaged sulfamic acid is placed in a bottle. A charge of urine is added to the bottle, and this results in a dissolution of the polyvinyl alcohol film and contact of the sulfamic acid with the urine, the sulfamic acid being quickly dissolved by the urine. The urine sample is permitted to stand and it is found that in addition to preventing bacterial degradation of the sample, the sulfamic acid maintains the pH of the urine sample sufiiciently low to prevent magnesium and calcium phosphate precipitation and also prevent degradation of steroids in the urine.
It will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and that the invention is not to be considered limited to what is described in the specification.
What is claimed is:
1. A package for use in the preservation of urine samples consisting essentially of an impervious film of sealable, water soluble plastic in the form of a closed and sealed container, and about 520 gms. of a water-free, strong acid preservative capable of being dissolved in urine contained within said sealed film container.
2. A package in accordance with claim 1 wherein said film is heat scalable, and is heat sealed to form said container.
3. A package in accordance with claim 1 wherein said water soluble plastic is a member selected from the group consisting of the polyvinyl alcohols, the alkyl cellulose, the hydroxyalkyl celluloses, the carboxyalkyl celluloses, polymers of ethylene oxide, gelatin, starch, the N-alkoxy methyl polypyrrolidones, carboxymethyl dextran, and sodium cellulose acetate sulfate.
4. A package in accordance with claim 1 wherein said water-free acid preservative consists of a solid anhydrous acid.
5. A package in accordance with claim 1 wherein said acid has a pK of less than about 2.
6. A package in accordance with claim 1 wherein said water-free strong acid preservative is a member selected from the group consisting of sulfamic acid, citric acid, oxalic acid, phthalic acid, maleic acid and benzene sulfonic acid.
7. A package in accordance with claim 1, further comprising therein, along with said strong acid, a preservativebactericide and an antioxidant.
8. A package in accordance with claim 7 wherein said preservative-bactericide is a member selected from the group consisting of boric acid, formaldehyde and thymol, and said antioxidant is a member selected from the group consisting of tannic acid and hydroquinone.
References Cited UNITED STATES PATENTS 2,580,414 1/1952 Duifey 206-84 2,750,027 6/1956 Cummings 206-0.5 2,824,842 2/ 1958 Sulkowitch. 2,854,317 9/1958 Free et al. 2,982,394 5/1961 Novak 206-84 XR 3,086,007 4/1963 Touey et al 206-84 XR 3,113,674 12/1963 Kiefer et al 252- XR 3,277,009 10/1966 Freifeld et al. 252-90 3,294,224 12/1966 Horwitz 2060.5 3,446,599 5/1969 Shand.
FOREIGN PATENTS 714,111 7/1965 Canada.
OTHER REFERENCES Martell et al.: Chemistry of the Metal Chelate Compounds, Prentice-Hall, N.J., 3rd ed., 1956 (pages 536- 537 relied on).
MORRIS O. WOLK, Primary Examiner B. S. RICHMAN, Assistant Examiner US. Cl. X.R.
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