Fentanyl test strips (FTS) are a type of immunoassay technology used as a harm reduction tool to detect fentanyl and many of its analogues in illicit drug samples. Although originally developed for urinalysis, they are now widely used to check drug supplies before consumption. FTS provide a rapid, low-cost method for people to gain information about their substance supply, helping lower the risk of accidental overdose. Understanding the proper procedure is necessary to ensure accurate results.
Preparing the Sample for Accurate Testing
The initial preparation of the drug sample is necessary for achieving a reliable result and avoiding a false positive reading. Begin by selecting a very small amount of the substance, approximately 10 milligrams (the size of a match head or a few grains of rice). This portion should be collected from the entire supply and thoroughly crushed or mixed to ensure it represents the whole batch.
Next, the sample must be dissolved in clean water. The volume of water is specific to the type of substance being tested. For most drugs, like heroin or illicit pills, approximately 5 milliliters of water (about one teaspoon) is sufficient for the 10-milligram sample. If the substance is a stimulant, such as methamphetamine, MDMA, or cocaine, a greater dilution is necessary to prevent a false positive result. Use a larger volume, closer to 10 milliliters (one full shot glass) of water, to reduce the concentration below the threshold where stimulants can interfere with the test. The substance must be completely dissolved, requiring thorough stirring until no solid particles remain.
The Step-by-Step Testing Procedure
Once the drug sample is fully dissolved, you can begin the physical testing process. Remove the fentanyl test strip from its sealed pouch and handle it only by the solid end to prevent contamination of the testing membrane. The strip has a marked maximum line near the bottom, which indicates the highest point the strip should be submerged.
Hold the strip vertically and dip the absorbent end into the liquid sample, ensuring the solution does not travel beyond the marked line. The strip should remain in the liquid for 10 to 15 seconds, allowing the solution to saturate the testing area. Remove the strip and place it on a clean, flat, non-absorbent surface to develop undisturbed. Allow the colored lines time to fully appear, which usually takes between two to five minutes.
Reading and Responding to the Results
Results are read based on the number of colored lines that appear on the strip. A negative result (fentanyl not detected) is indicated by two distinct lines: the control line (which must always appear) and the test line. Even if the test line is very faint, the result is negative. A positive result (fentanyl or an analogue detected) is indicated by only one line appearing (the control line).
A positive result requires strict adherence to harm reduction measures. While discarding the substance is the safest action, if consumption is chosen, several safety protocols must be followed. These include using a significantly smaller test dose, never using the substance alone, and ensuring naloxone (Narcan) is immediately accessible and that someone nearby knows how to administer it. An invalid test occurs if no lines appear or if only a line appears on the wrong side; repeat the procedure with a new strip.
Understanding Test Strip Limitations
A negative result does not guarantee the entire substance supply is safe to use. Fentanyl may not be distributed evenly throughout a batch of drugs, creating “hot spots” of high concentration. A negative test result only confirms the absence of fentanyl in the specific portion of the drug that was dissolved in the water.
Current test strips may not detect every single fentanyl analogue, which are structurally similar compounds that can have varying potencies. While the strips are designed to detect many common analogues, there are hundreds of variants, and some may not cross-react with the test’s antibodies, leading to a false negative result. False positive results can also occur if the sample was excessively concentrated, especially when testing stimulants. This reinforces the necessity of following proper dilution guidelines. Regardless of the test outcome, always follow established harm reduction practices.