The temperature strip on a drug test collection cup verifies the integrity of the urine specimen. This check is the first line of defense against tampering and is mandatory in nearly all standard drug screening protocols. The strip confirms that the collected sample is fresh and was recently expelled from the donor’s body.
Why Temperature Validation is Crucial
Checking the temperature prevents two main types of deception: substitution and dilution. Substitution involves replacing urine with a pre-collected, stored, or synthetic sample. Since a sample that has been sitting out or concealed will cool down, an out-of-range temperature suggests the sample did not come directly from the donor’s body.
A temperature check also helps detect attempts to dilute the sample with cold tap water or other liquids, resulting in a temperature that is too low. A freshly voided sample from a healthy person falls within a predictable and narrow temperature range. This check ensures the specimen’s authenticity before laboratory testing begins.
Interpreting the Temperature Strip Readings
The temperature strip is a band of liquid crystal material affixed to the exterior of the collection cup. This strip contains heat-sensitive elements that change color when exposed to the specimen’s heat. Because the sample begins to cool immediately, the collector must take the reading within four minutes of the donor providing the specimen.
The acceptable temperature range for a valid urine sample is specific, falling between 90°F and 100°F (32°C to 38°C). This range reflects the expected cooling from normal body temperature (approximately 98.6°F or 37°C). The strip displays multiple numbers or temperature points.
To read the strip, the collector looks for a specific color, often green or blue, that appears next to a number on the scale. This color indicates the actual temperature of the specimen. If the indicator appears within the 90°F to 100°F range, the sample is valid. If the indicator color does not appear in this acceptable band, or if it appears next to a temperature that is too high or too low, the sample is considered out of range.
Actions Taken for Invalid Temperature Results
If the temperature strip shows a reading outside the acceptable 90°F–100°F range, the sample is immediately flagged as “out of range.” A temperature that is too low or too high suggests tampering, either through substitution or adulteration. The original specimen cannot be used for testing and is treated as suspect.
The immediate protocol requires the donor to provide a second specimen. This re-collection is often performed under direct observation to ensure validity. The collector documents the temperature reading and the reason for suspected tampering on the custody and control form.
The consequence of an out-of-range temperature can be significant, as failure to provide a valid sample is often considered a refusal to test or an invalid test. For regulated testing, both the original out-of-range specimen and the new, observed specimen are sent to the laboratory. The donor may face consequences, such as removal from a safety-sensitive position, depending on the employer’s policy.