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Q: Storing and preserving human urine ( No Answer,   0 Comments )
Subject: Storing and preserving human urine
Category: Science
Asked by: jollydog-ga
List Price: $20.00
Posted: 03 Mar 2006 13:19 PST
Expires: 02 Apr 2006 14:19 PDT
Question ID: 703324
We need to collect and store human urine samples in low resource
settings (third world countries). The samples need to be kept on hand
for at least one year in sealed plastic 2 ounce vials, similar to
shampoo sample bottles. Refrigeration is not on option. However
storage will be at ambient room temperatures. Will the urine degrade,
"go bad" or be compromised in some other way? What preservative
(sodium benzoate?) is recommended? These samples will need to be
pulled and subjected to toxicology screens at random intervals. We
would prefer to not use any sort of preservative if possible.

Request for Question Clarification by sublime1-ga on 03 Mar 2006 16:32 PST

According to this page, even frozen urine will only last about 
one year:

At room temperature, urine is typically preserved with tartaric
or boric acids, but this only lasts 24-72 hours, according to
this page at Becton, Dickinson and Company (BD):

"A variety of urine preservatives (tartaric and boric acids
 being the most common) are available that allow urine to
 be kept at room temperature while still providing results
 comparable to those of refrigerated urine. Generally, the
 length of preservation capacity ranges from 24 to 72 hours."

I can't imagine a preservative that would keep urine at room
temperature for a year, precluding the growth of bacteria 
while still allowing for accurate testing of any kind.
Perhaps there's a way to turn it into a powder, but I doubt
that a freeze-drying process would be available to you in a
third world environment if refrigeration is not, and any 
slower method will result is deterioration, making it of no
use for testing purposes, as noted by this comprehensive
review of urinalysis on FindArticles:

"...delays of more than two hours between collection and
 examination often cause unreliable results"

Let me know where this takes you...


Clarification of Question by jollydog-ga on 05 Mar 2006 15:21 PST
please let us know the concentrations/ratios of using boric or
tartaric acid and consider this question answered. another related
question: How is synthetic urine manufactured? will be posted and we
would like you to answer this for us.

Request for Question Clarification by sublime1-ga on 06 Mar 2006 12:35 PST

I hesitate to provide an answer, since I have not satisfied the
condition of finding a preservative which will last a year, but
only 24-72 hours.

Additionally, boric acid is not the preferred means of preserving
urine specifically for drug testing, as shown by this spreadsheet
in PDF format from the Mayo Clinic, which defines the various
types of urine screens, and the preferred preservatives for same:

Refrigeration is the preferred means of preservation for drug
screens. Boric acid is used for others, as you can see, and is
much more commonly used for 24-hour tests, such as Microalbumin,
and others, as listed.

A 24-hour test is one in which the patient is given a big plastic
container to which is added approx. 15g Boric acid, dissolved in 
about 10 mL distilled water. The patient then collects urine for
the next 24 hours, barring the first sample of the day. Boric acid
preserves the urine over the 24 hour period of collection, and for
up to 72 hours total, as noted on this page from Bi-Lab:

The choice of preservative depends very much on the type of test
being conducted, and I don't know whether boric acid would thus
interfere with a drug screen or whether refrigeration and rapid
testing is preferred for other reasons, but it is not the method
of choice for preserving urine destined for drug testing.

Tartaric acid is used so little as to return few results when
searched for.

Let me know where this takes you. If the research satisfies your
interests without having provided a solution, let me know, and
I'll post a formal answer.

There is no answer at this time.

There are no comments at this time.

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