Specimen validity test.
Seven different tests establishing the integrity of human urine.
Every drug test should be supported with a specimen validity test. Without this test you can never be certain that the urine sample you are testing for drugs is real or has been tampered with. By using a specimen validity test you can check many aspects of the urine to ensure its integrity. (see ‘Interpreting the test’)
The use of adulterants can cause false negative results either by interfering with the screening test and or by destroying drugs present in the urine. Dilution may also be employed in an attempt to produce false negative result. Dilution of urine with water is probably the simplest urine adulteration method. Bleach, vinegar, Visine, sodium bicarbonate, sodium nitrite, Drano, soft drinks and hydrogen peroxide are the examples of adulterants used to adulterate the urine sample due to cheating the drug test.Data Sheet
Instructions for testing.
- Collect fresh urine from the donor in a clean specimen container.
- Test urine sample as soon as possible after collection.
- Handle the urine sample as if it is potentially infectious.
- Aliquot a small portion of the urine sample into another container for testing in order to avoid contamination of the whole urine sample.
- Do not dip specimen test strip directly into the specimen container.
- Completely immerse reagent areas of the strip in fresh, well-mixed urine. Remove the strip immediately to avoid dissolving out the reagent areas.
- While removing, touch the side of the strip against the rim of the urine container to remove excess urine.
- Blot the lengthwise edge of the strip on an absorbent paper towel to further remove excess urine and avoid running over contamination from adjacent reagent pads.
- Compare each reagent area to its corresponding color blocks on the color chart and read at the times specified. Proper read time is critical for optimal results.
- Obtain results by direct color chart comparison.
- If the test indicates adulteration, ask the donor to provide a new sample.
- Read all reagent areas between 1 – 2 minutes to determine positive urine from negative urine.
- Changes in color after 2 minutes are of no value.
Color comparison provides a semi-quantitative screen for Creatinine, Nitrites, Glutaraldehyde, pH, Specific Gravity, Bleach and Pyridium Chlorochromate in human urine which can help to assess the integrity of the urine sample.
For best results, performance of reagent strips should be confirmed by testing known negative and positive specimens or controls whenever a new test is performed or whenever a new bottle is rust opened. Each laboratory should establish its own goals for adequate standard of performance, and should question handling and testing procedures if these standards are not met.
Comparison to the color chart is dependent on the interpretation of the individual. It is therefore, recommended that all laboratory personnel interpreting the results of these strips be tested for color blindness.
Some compounds or physical properties that may affect the test result are listed below. Medications that discolor the urine may also cause abnormal results due to masking of-the-reactions of the reagents on the test pads.