Blue Fentanyl Test Strips


These are the instructions for the older, blue fentanyl test strips, most of which are manufactured by the Chinese company, Assuretech. The Bunk Police no longer sells the blue fentanyl strips, because they often produce false positives with meth, MDMA and cocaine that contains levamisole.

Because these strips are still being sold by other companies under various brand names, we have maintained our old instructions to help you use them if needed. With the blue strips, it is extremely important to dilute your substance properly to avoid false positives and false negatives.



Unless you know the exact milligram amount of MDMA in your pill, it is impossible to accurately test pressed ecstasy tablets with the older, blue fentanyl strips. Even if you believe your pills contain a certain amount of MDMA, you cannot determine the amount of binder material versus active substance without sending your sample to a lab. Most dealers are not aware of the amount of MDMA in the pills they’re selling, even if they believe they are.

About the Blue Fent Strips

Our fentanyl testing strips have been acutely evaluated by a highly-skilled team of researchers at the University of California San Francisco, as well as at our own laboratory in the European Union. Our test strips are capable of detecting incredibly small amounts, even trace amounts, of fentanyl, along with many of its known analogs—including carfentanil (an analog 10,000 times more potent than morphine, and 100 times more potent than fentanyl) and acetylfentanyl (a common analog that’s weaker than fentanyl, but still 15 times stronger than morphine). 

These kits—along with every other kit on the market—have limitations. There is no method available today capable of detecting every fentanyl analog. However, we can confidently guarantee that our FentKits will detect the most common and dangerous versions—more than most on the market currently do. 

Our strips have been verified to positively identify the following:

Fentanyl — 200 ng/
Carfentanil — 1,000 ng/ml
Butyryl Fentanyl — 700 ng/ml
p-Fluoro Fentanyl — 200 ng/ml
Acetyl Fentanyl — 150 ng/ml
Furanyl Fentanyl — 500 ng/ml
Valeryl Fentanyl  — 700 ng/ml
Ocfentanil  — 250 ng/ml
3-Methyl Fentanyl  — 500 ng/ml
Remifentanil  — 70,000 ng/ml
Sufentanil  — 100,000 ng/ml

CAUTION! Fentanyl test strips from other sources may not detect all necessary fentanyl analogs. Some versions (mostly from Chinese manufacturers) are not verified to function correctly. Five different strips from three different manufacturers have been evaluated by UCSF. Four did not detect carfentanil, and one set of strips from a Chinese manufacturer did not function at all. DO NOT trust fentanyl test strips that do not contain both antibodies. This is crucial for your safety.



Older (Blue) Fent Strips Instructions

Testing everything you intend to consume

Though we understand this method is not always practical, it is the only way to ensure your substance is truly free of fentanyl and the majority of its analogs. Testing every bit of the substance you intend to consume is the best method for testing non-injected substances—including powders, crystalline, or tablets. 

This requires first dissolving the whole sample you intend to consume in water. You can still consume the sample by drinking the water after testing (even with drugs that are typically snorted, such as cocaine or meth). Alternatively, you can let the water evaporate and consume the substance later. It is also possible to put your sample in a food dehydrator to evaporate the water much more quickly—within an hour or less. Evaporation without a dehydrator could take anywhere from a few hours to a few days, depending on heat and humidity, but it will not affect your substance.



  1. Place all of the substance you intend to consume into a test tube, glass, or ceramic cup.
    1. If you are testing a pressed pill, first crush it into a powder. 
  2. If you are testing MDMA or methamphetamine:
    1. Add 1 teaspoon of water (about 5 ml) for each 10 mg of crystal or powder you are testing (a little less than a “bump.”)
    2. Ensure this ratio (2 mg per 1 ml of water) is correct for meth and MDMA. 
      1. Too little water used when diluting (the substance is too concentrated) can give a false positive.
      2. Too much water used when diluting can make it harder to detect potential fentanyl. 
  3. If you are testing ANY drug other than MDMA or meth:
    1. Add 1 teaspoon of water per 100 mg of crystal or powder.
  4. Stir the contents until they are thoroughly dissolved.
    1. Binder materials in tablets may not dissolve. 
  5. Dip a test strip into the tube / glass / cup (see “HOW TO USE TEST STRIPS” below).


Testing the residue inside your baggie

CAUTION! This is not the recommended method for testing. The best method is to test every bit of your sample that you intend to consume (as described above). This method has a higher chance of producing false negatives than Method One. Due to the uneven mixing of fentanyl in drug manufacturing, it is still possible your drug contains fentanyl if you only test the substance residue. However, if you are unwilling to dissolve your entire dose before consumption, this is the next-best option (and still better than not testing at all).



  1. Empty the powder or crystals inside of your baggie onto a plate, and crush or chop them into the finest powder possible.
    1. A straight razor blade is best for fine chopping, and you can use the bottom of a metal spoon for crushing.  
  2. Now, put the powder back into the baggie. Seal the bag and shake it well, then open it and dump the powder back out again. Now you should have a baggie with well-distributed residue stuck to the inside walls. 
  3. Put about a ½ teaspoon (about 2.5 ml) of water into the baggie. 
  4. Seal the bag tightly, and swish around to dissolve the residue. 
  5. Dip a test strip into the baggie (see “HOW TO USE TEST STRIPS” below). 


If you are testing MDMA or methamphetamine:

  1. Depending on how much residue is stuck to the inside of the baggie, you may need to use a full teaspoon of water (about 5 ml) for each 10 mg of crystal or powder you are testing (a little less than a “bump.”) 
  2. This is because the dilution ratio needs to be 2 mg per 1 ml of water for meth and MDMA. 
    1. Too little water used when diluting (the substance is too concentrated) can give a false positive.
    2. Too much water used when diluting can make it harder to detect potential fentanyl. 
  3. If we assume there is about 10 mg of residue stuck to the inside of the bag, then 1 teaspoon of water (5 ml) is the proper amount. 

Testing injected substances

If you inject substances, you need to test every time you do so. The best method for injected substances is to test the residue from your spoon or cooker. After preparing your shot, set the needle aside, and test the residue before you inject.



  1. Add a small amount of clean water into the spoon or cooker with the residue of the substance—1 mm or 1/4 teaspoon of water is enough.
  2. Use the bottom end of a clean needle to swirl the water around inside the spoon or cooker.
  3. Dip a test strip into the spoon or cooker (see “HOW TO USE TEST STRIPS” below).


HOW TO USE BLUE TEST STRIPS (once your sample is dissolved)

  1. Make sure you dissolve your substance into water using one of the three methods. 
  2. Hold the solid blue end of the test strip, and insert the other end into the liquid, no higher than the horizontal blue line.
  3. Allow the liquid to travel up the strip into the test area—this takes less than 30 seconds. 
  4. Set the strip down on a flat surface and wait about 2 minutes
  5. See “Interpreting Test Results” below.



ONE red line ON TOP (closest to the solid blue end): 

  1. The test is POSITIVE for the presence of fentanyl, or one of its analogs.


TWO red lines:

  1. The test is NEGATIVE for the presence of fentanyl, or one of its analogs. 
  2. Any second line, including a very faint line indicates that the test is negative for the presence of fentanyl. 


NO red lines, or one red line on the bottom (closest to the blue squiggly end): 

  1. The test is INVALID. 
  2. The liquid most likely did not go far enough up the strip.



  1. When testing cocaine, a positive reaction could indicate the presence of either fentanyl or lidocaine.

Please assume any positive result indicates the presence of fentanyl, and encourage others to stop using lidocaine as a cutting agent.

Purchase FentKits Here