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A new study has been published in the Harm Reduction Journal evaluating the effectiveness of nitazene immunoassay test strips. As a provider of drug checking tools, we believe it is vital to engage with new research to ensure our community has the most accurate information available. The paper, “Evaluation of nitazene immunoassay test strips for rapid in-situ detection of nitazene and nitazene analogs in illicit drug samples,” provides some important data, but also contains findings that could be easily misinterpreted without proper context.

This blog post will break down the study’s key findings, address some of its more conclusions, and clarify what this means for people using test strips as a harm reduction tool in the real world.

The Caffeine “False Positive” – A Matter of Interpretation

One of the paper’s headline findings is that the test strips produced false positives when testing seized heroin samples, which they attribute to high concentrations of caffeine, a common cutting agent.

However, a crucial detail is lost in this summary. The researchers themselves note that a “faint line” appeared on these tests. According to the manufacturer’s instructions—and a fundamental rule of interpreting these strips—any line or mark in the test region (T), no matter how faint, must be considered a negative result.

Therefore, calling a faint line a “false positive” is a significant misinterpretation. It is more accurately described as interference that causes the negative-result line to fade. This is an important distinction because it can cause confusion and lead people to discard a substance unnecessarily. While a false positive is far less dangerous than a false negative, correct interpretation is key to building trust in these tools.

While the paper tested strips from the manufacturer BTNX (which Reagent Tests UK does not sell), our own in-house tests on the strips we provide show a similar fading effect from caffeine, but only at very high concentrations, typically above 1mg/mL (1000µg/mL). The researchers found that a true false positive—the complete disappearance of the test line—only occurred with extreme concentrations between 7-10mg/mL.

Do Faint Lines Matter? A Look at Real-World Concentrations

This brings us to the most relevant question: could a high concentration of caffeine mask a dangerous amount of nitazene? Let’s look at the numbers.

If we take the worst-case scenario from the paper, where a true false positive is caused by caffeine at 7mg/mL (7000µg/mL), the test strip is still incredibly sensitive. A strip with a Limit of Detection (LOD) of 3000ng/mL (3µg/mL) could still detect a nitazene analog present at just 0.04% of the total sample weight (3µg nitazene / 7000µg caffeine).

To put that in perspective, the potent nitazene analog etonitazene is roughly 1,500 times the strength of morphine, or about 100 times the strength of heroin. A heroin-equivalent dose of etonitazene would require it to be present at over 0.10% of the total mass. Therefore, a test that can detect nitazenes down to 0.04% is more than capable of identifying a dangerously adulterated sample, even in the event of it being cut with extreme amounts of caffeine.

Using 1mg/mL as a standard testing concentration would allow detection of 0.28% nitazenes in dry mass even for those which are hardest to detect, and 0.05% for easier to detect compounds like N-desethyl etonitazane.

The Real Concern: Undetected “Desnitazenes”

While the caffeine issue has been overstated, the paper raises a far more critical point: the tested strips were unable to detect ‘desnitazene’ analogs. These are compounds like metodesnitazene or etodesnitazene, which lack the “nitro” group from their chemical structure.

The study found that the BTNX strips failed to produce a positive result for these compounds, even at high concentrations. This represents a genuine risk of a false negative. With etodesnitazene possessing a potency of around 70 times that of morphine, its undetected presence in a substance believed to be heroin could easily lead to an overdose.

This is the most significant takeaway for the harm reduction community. We must be vigilant for the appearance of these desnitazene analogs on the market and recognise the current limitations of immunoassay strips in detecting them.

The Golden Rules of Harm Reduction Testing

This research underscores a core principle of drug checking: it can never be used as a guarantee of safety. Instead, testing is a powerful tool to prevent the most dangerous situations from arising, such as encountering a potent synthetic opioid when expecting traditional heroin.

It is just one tool in a much larger harm reduction toolbox. Its use must always be accompanied by other essential practices:

• Start with a small test dose (“start low, go slow”).
• Never use alone.
• Have naloxone on hand and know how to use it.
• Be aware of the limitations of your testing equipment.

Correct test procedure is also non-negotiable. For nitazene strips, this means:

1. Dissolve a very small amount of your sample (a tenth of a dose is a good guide) in about 10mL of water.
   • Using warm water and a little lemon juice can help ensure everything dissolves.
2. Dip the strip into the liquid up to the MAX line for 15 seconds.
3. Place the strip on a flat, dry surface and wait 5 minutes.
4. Crucially: two lines, even if one is faint, is a negative result. One line is a positive result. No control line means the test is invalid.
5. If you get an unclear result, add 10x more water to the sample and test again.

If you get an unclear or positive result:

1. Take a photo of the test strip, the liquid tested and the sample
2. Contact Reagent Tests UK (testresultquestions@[ this web URL from this page].uk)
3. Dilute the liquid so you have 1mL of water for every 1mg of substance you added previously
4. Repeat the test procedure and record the results.
5. If you still get a positive result it is likely that you actually have nitazenes in the sample. Please contact us to arrange further testing and get a gift card.

Conclusion: A Valuable Tool, If Used Correctly

The recent study provides valuable data for the harm reduction community. However, it is essential that its findings are interpreted correctly. The risk of false positives from caffeine is low if users are properly informed that a faint line is a negative result.

The far greater risk is the inability of current strips to detect ‘desnitazene’ analogs. This highlights the need for ongoing research and continuing to combine different harm reduction tools to ensure all risks are mitigated.

Ultimately, nitazene test strips remain a vital and valuable harm reduction intervention. They empower people to make more informed decisions about their substance use. It is critical that researchers, healthcare providers, and community members all understand how to use and interpret these tests correctly, acknowledging their strengths and their limitations. By doing so, we can maximise their life-saving potential.

Introduction

LSD is a highly potent psychedelic drug, with a teaspoon of crystals (3g) providing enough for 30,000 doses. It’s normal for the potency of different drugs to be different and there are many pharmaceuticals with this kind of potency. What’s difficult is that home equipment cannot easily measure out the 100 micrograms required for a dose.

To address this, LSD is distributed in pre-measured form. Dissolved in liquid (1 dose per drop) or soaked into blotter paper (1 dose per 5mm square). Less common is to stir the LSD into gelatin, then pour it out to set. The gelatin can be broken off in squares which represent one dose.

The problem is, gelatine can react directly with reagent test to give confusing results. This means we have to separate the LSD from the gelatine. Luckily, this process is very easy, simply requiring chlorine-free water to extract the LSD.

Boiling water sterilises it and removes any chlorine that could damage the LSD, and gelatine doesn’t dissolve well into it.

Equipment

You will need:

• Recently boiled water that has cooled below 80*C
• Something to manipulate the water like a syringe, pipette or even a teaspoon
• A geltab
• A small container to dissolve the geltab in, such as a shot glass
• Absorbent paper, cut into a 1cm x 1cm square

Procedure

1. Boil the water and start cooling
2. Dip the container into the water to pre-heat it, then take it out
3. Put the geltab into the container
4. Add half a teaspoon of the water (1 mL).
5. The mixture must be at least 40*C for at least 5 minutes.
6. Cover the container
7. Allow to soak for 24 hours
8. Place the paper square on the side of the container, half in the water and half out.
9. Leave the container un-covered to evaporate. The water will migrate into the paper, carrying the active chemicals with it.
10. You can now treat the paper like a normal piece of blotter, so cut off a quarter and place the test granules on top.

This is a guest post by the pseudonymous Reddit contributor “Borax”

6-APB is an “empathogenic” (empathy-generating) drug which is structurally related to MDMA. It has very similar effects to MDMA but is often said to have a more psychedelic headspace, with a slightly more intoxicated feeling and a different perspective compared to the relative clarity of the MDMA headspace in doses around 100mg. The duration of 6-APB is a little longer than MDMA at around 6-8 hours compared to 5-6 hours.

The dosage, however, is much harder to sum up in a single sentence. 6-APB has a curious history that shines some light on its chemical variability and helps us to uncover ways to reduce the risk when consuming it.

A summary of this article:

1. 6-APB can contain a lot of the inactive isomer 4-APB
2. 6-APB can come in two different forms, one of which contains less molecules of 6-APB in each gram
3. One form takes longer to dissolve in the stomach and can therefore trick people into taking more before they are feeling the full effects
4. The same form is likely to contain a chemical left over from production. It’s thousands of times less dangerous than 6-APB and therefore not concerning but it also reduces the number of 6-APB molecules present in a powder.

It’s not possible to tell how many molecules of 6-APB are present in a particular batch without using a lab test. Therefore if you are considering taking 6-APB then you need to start with a low dose and work up over a few sessions, you must not jump in and start with a dose you have read online because you don’t know how potent your batch could be. People with the strongest form of 6-APB in high purity seem to take 70-90mg even when they are experienced.

Why does all of this happen with 6-APB but not other drugs?

The sale of 6-APB was first announced online in early-summer 2010 under the brand name “Benzo Fury” but it was not actually made available until the autumn after the release date of a full sized batch was repeatedly pushed back for undisclosed reasons. When it was finally released, early adopters commented that the appearance was more floury, not crystalline and that the effects took longer to kick in but but with everything else behaving as it should there wasn’t much concern over this.

It’s taken a few years to uncover a plausible explanation for this but 9 years later we have two major contributing factors to work with that help explain what might be happening.

The presence of isomers of 6-APB in the sample.

Using 6-bromobenzofuran as an easy intermediate for the production is ideal for vendors focused on their profit margins but isn’t so good for the consumers who might be willing to pay a bit more for a higher purity product. Bromination of benzofuran in the 6 position has a tendency to produce reasonable amounts of 4-Br-benzofuran.[1]

If producers don’t make the effort to remove these then the end product can have 4-APB present which has minimal pharmacological activity, and indeed this was regularly reported by analysis services when 6-APB at its peak popularity.[2][3]

The big difference between the two different “forms” of 6-APB (hydrochloride and succinate)

6-APB is basic, so has a high pH in its natural form. This means it can react with acids to neutralise them and form a salt. Just like sodium can react with different acids to give different salts (sodium chloride or sodium bicarbonate for example), so too can 6-APB.

Most basic drugs are reacted with hydrochloric acid for a number of reasons which could be simplified to “it’s cheap and easy to make salt crystals with” and this is usually the preferred form for most people. For MDMA crystals the hydrochloride component is so ubiquitous that most people just forget about it and scientists debate whether that’s OK.

With 6-APB it’s not so easy. For some reason 6-APB isn’t easy to crystallise with hydrochloric acid and it causes problems for bulk producers. While producing a higher purity product can sometimes circumvent these issues it was not the route that producers selected and instead they chose to start using succinic acid instead.

There is an immediate issue here; the succinic acid molecule is very big and heavy. In the best case, where we could have two molecules per 6-APB molecule, the hydrochloric acid form contains 10% more molecules of 6-APB per gram. In the worst case scenario that rises to 39%, as it could be necessary to have as much as a 1:1 ratio of succinic acid to 6-APB before we get a manageable solid form.

Succinate salts aren’t as easy to dissolve

This one is fairly self explanatory. Before a drug can be absorbed into the gut it has to dissolve into the stomach or mucus contents. If it takes a long time to dissolve then it takes a long time to be absorbed. Slowing the absorption delays the peak and some people report no effects for 1-2 hours. This is uncommon among drugs and can cause people to take more even though they don’t need to.

Succinic acid gets left behind by producers

One of the reasons that hydrochloric acid is preferred is because it is a gas when it is completely dry. This means that producers can bake something like MDMA hydrochloride in an oven and all the remaining hydrochloric acid evaporates with the last of the water.

Succinic acid isn’t so easy and its normal form is a powdery solid or crystal. This means that if a producer adds too much then it’s lots of work to remove. We don’t know why (time = money perhaps) but they don’t always do this work and batches with even lower potency than is theoretically reasonable have been found.

What does all this mean for me?

You might have noticed that a big theme in these is “uncertainty” and I think that’s a fair take-away. The hydrochloride form should be more consistent but vendors aren’t always honest about which form they sell, assuming they know at all.

The only way to bypass these issues is to get a laboratory purity test from an organisation like Energy Control International. If you don’t have access to that then you can verify that you actually have some 6-APB using the marquis reagent test and from there you need to work your way upwards slowly if you’re comfortable with the risk of taking it.

North & West Devon police have issued a warning about “Darth Vader” tablets today, saying that “it is a dangerous mix of MDMA, ketamine and cocaine”. This is very surprising as ecstasydata has never recorded a single incident of pills with this combination of drugs over the last 15 years. After being asked, N&W Devon police reveal that the pills have not been lab tested.

In the absence of any real knowledge, can we critically analyse the speculation about the contents?

MDMA is commonly distributed in tablets for a variety of reasons, namely the increased ease of dosing and ability for “brand recognition” to supposedly make it easier to identify fake pills with more dangerous contents. Unfortunately, with pill production equipment readily purchasable on Amazon, this is not an effective strategy. So the suggestion that there could be MDMA in these tablets is certainly plausible.

Cocaine however, is almost never seen in pills, and for very good reason. Cocaine contains two “ester” bonds in the molecule, which are very vulnerable to being broken down by water and acids. Since the stomach is a strongly acidic environment, when cocaine is eaten it starts being broken down immediately, and then gets passed to the liver which destroys more. This means the dose of cocaine required when taking it orally is much higher. In order to include a meaningful amount of cocaine in an ecstasy tablet would therefore massively increase the price of the tablet. As well as this, cocaine is a strong local anaesthetic (causes numbness) so any would-be user who put the pill into their mouth would immediately realise something unusual was afoot when their tongue started to go numb.

Ketamine is another drug which is almost never taken orally because it too is fragile, and easily dismantled by the liver. Since all blood from the stomach passes through the liver before going to the brain, this means that a lot is destroyed before it can affect the body. Coupled with the fact that absorption from the gut is much slower than the nose, this means a very high dose is needed to reach the same concentration in the brain. The outcome of this is that adding a meaningful amount of ketamine to a tablet would massively increase the size of the tablet.

Trying to add a meaningful amount of all three of these drugs to a tablet would likely result in an enormous tablet which was incredibly expensive and immediately identifiable as abnormal, even by black market standards.

So, is it possible? Yes. But is it likely that a pill containing this combination of drugs has been detected for the second time in 12 years? No. I would argue that any authority claiming to have discovered something very unusual should apply extra scrutiny to that discovery before announcing it to the public, and possibly consult with experts beforehand, at the very least to apply a sense-check.

With all this said, it is refreshing to see a police force sharing as much information as they can (good photos and suspected contents) in the interest of public health – I suspect that the damaging cuts to public services over the last 8 years have impacted the ability of the police to access experts at short notice within their budgets. Perhaps by waiting a few days for a test result confirmation could have meant more people falling victim to these tablets. Really what we should be calling for is the central government to provide funding for testing facilities that are more easily accessible.

Until then, home users can use simple reagent tests to alert themselves to cases where a different drug has been sold in place of the one they were expecting.

Taking drugs is risky business – doctors have to spend so long in training because humans are complex and their reactions with drugs aren’t always easily predicted. Fortunately for doctors, prescription drugs are tightly regulated and in developed countries counterfeits are extremely rare – when you get 10 mg Ritalin tablets prescribed, you can be sure that each tablet will contain exactly 10.0 mg of Ritalin, and you’ll be able to get great advice from your doctor about the most effective way to take them.
Unfortunately the recreational market has no regulation whatsoever – the government leaves quality control in the hands of criminal organisations, and they’ll sell whatever makes the most money for them. Unfortunately this often means that drugs are impure and in some cases they can be something else altogether, without a trace of the advertised ingredient inside. Without the ability to rely on Trading Standards to fix this, we have to take matters into our own hands. But without the multi-million labs used by government organisations, how are we supposed to do any real testing?

It’s true that testing at home isn’t as good as testing in a lab, but if we can identify when a sample has been mis-sold, then we have the chance to avoid the problems associated with not knowing what we’re taking and remove a lot of the potential for harm. And luckily for us, while detailed chemical analysis can be challenging, simply telling whether a white powder contains Molecule A or Molecule B can actually be very easy.

Reagent tests work by changing colour roughly based on the “functional groups” or types of atom in a molecule. If Molecule A has an oxygen double bonded to a carbon and molecule B does not, then it will give a different colour. Bingo. We usually use three different “reagents” because some molecules have similar groups inside them, and each reagent is sensitive to different groups.

The best part is that we don’t even need to know which bonds or groups a molecule has because we can just compare the colours we get to what we should expect for the compound we want. So at the end, we compare our three colours to a “reaction chart”, and if any of the colours don’t match then we know that we don’t have the molecule we expected.

Step 1 – Determine which drug you think you have.

If you don’t know what compound you’re expecting, you won’t know which colour change to expect.

Step 2 – Determine which reagents you need

Because different reagents work best with different drugs, it helps (but it is not essential) to match up the best reagent. At Reagent Tests UK we’ve named our multipacks according to which drug they are most suitable for, so this bit is done for you, but we’ll go into the science, in case you’re interested.

Testing MDMA

The MDMA testing multipack is a kit of three reagents selected for testing suspected MDMA. The marquis reagent is very popular and has a wide range of known reactions, even for uncommon adulterants. The froehde reagent has a great shelf life and picks up PMA being sold instead of MDMA, as well as helping to identify 2C-B in pills. Finally, the mecke reagent allows us to identify DXM, which has a similar reaction to MDMA with the marquis reagent but very different effects (black vs dark grey for marquis but black vs yellow for mecke).

Testing Cocaine

Cocaine is a little trickier to test because the molecule itself doesn’t change colour with the marquis reagent. But that gives us a great opportunity to use the marquis reagent to see if amphetamine has been added, since amphetamine turns red to brown over about 30 seconds. Then we have the liebermann reagent which goes orange with cocaine to make sure there is actually some cocaine there. Finally the mandelin reagent allows us to identify some other cuts – it goes blue with vitamin C, orange/brown with benzocaine and greenish brown with levamisole as well as reacting with ibuprofen, paracetamol and procaine. These three reagents come together in the Cocaine Testing Kit

Testing Ketamine

Ketamine is a tricky one because it doesn’t react strongly with anything but we can use reagents to see if it’s been cut. The liebermann reagent goes light yellow with ketamine, but for methoxetamine (MXE) it goes orange-brown and for 3‑MeO‑PCP it goes a dark reddish brown. We can use the mandelin reagent to narrow things down as it goes green for 3‑MeO‑PCP and doesn’t change colour for methoxetamine. This can be very useful because most people don’t want their ketamine trip to last 6-8 hours from a tiny bump! That means we can use the Cocaine testing kit as a perfect way to check ketamine for dodgy goings-on.

Testing 2C-B

2C‑B is a psychedelic drug which is sometimes sold as pills or powder and has a very strong effect from a tiny amount. Lots of people enjoy this but you wouldn’t want to take an MDMA sized dose expecting the effects of MDMA and end up in a strong trip! 2C‑B turns green with the marquis reagent and yellow with the froehde reagent. If you’re considering blotter paper as the dosage form then the ehrlich reagent allows you to see if LSD might be present, as it goes purple for LSD but provides no colour change when testing 25I‑NBOMe, 2C‑B, DOB and the others in these series. We have our MDMA & psychedelics testing kit with the right reagents for these compounds.

Other compounds

The great thing about reagents is that they change colour with almost every drug, and we include a reaction colour chart and instructions with every order. So no matter what you were expecting, you can see if you’ve been sold something else instead. Don’t forget that even if your compound is what you expected you should still be careful, and very pure drugs can be a big risk if you start with a big dose expecting something less pure. So ideally weigh how much you’re taking, and if you’re not weighing something like MDMA then always #CrushDabWait.

If you’re using more than one of these on the list then don’t forget we also offer a combination kit to test drugs which contains our five most popular reagents.