How to test cocaine purity?
This version has been translated from Polish and links to the relevant test kits have been added. In a life-threatening situation call 112. This article is informational and serves harm reduction. It does not encourage the use of psychoactive substances and does not replace medical advice.
You do it in three steps, and the order matters: confirm it is cocaine, rule out the cuts, then measure the strength. Skipping to the third produces a confident wrong answer, for a reason we come back to below.
Single-use cocaine test, 3.65 EUR · Cocaine and cuts kit, 31.4 EUR
European cocaine is stronger than people assume
Of the samples European drug checking services have published, 523 carry a laboratory purity figure.
| Purity | |
|---|---|
| Median | 86% |
| Mean | 77.7% |
| Over 80% | 339 samples |
| Under 50% | 70 samples |
| Range | 1% to 100% |
The folk model of cocaine, mostly chalk and filler with purity in the thirties, is a decade out of date here, and the correction cuts both ways. If you learned your dose on 40% material and the market moved to 86%, the same line is now more than twice the drug, so a high median is a dosing hazard rather than good news. And it is a median, so half the samples sat below it and 70 came in under 50%. Neither of those is visible in the powder, which is why both tests below exist.
What else is in it
337 of 767 samples, 44%, contained something besides cocaine. These are detections, so a sample carrying both procaine and levamisole counts twice.
| Detected alongside cocaine | Detections |
|---|---|
| Procaine | 95 |
| Caffeine | 74 |
| Levamisole | 61 |
| Phenacetin | 45 |
| Benzoylecgonine | 44 |
| Norcocaine | 28 |
| Ketamine | 21 |
| Paracetamol | 20 |
| Tetramisole | 17 |
| Lidocaine | 14 |
| Tropacocaine | 13 |
Grouped by sample, three families matter for different reasons. Local anaesthetics turn up in 108 samples and are there to reproduce the numbing people use as a purity test, which is exactly why the numbing test is worthless. Levamisole and tetramisole appear in 78, and levamisole is a veterinary dewormer that causes agranulocytosis, a collapse in white blood cell count, in a small proportion of regular users. Coca alkaloids appear in 71 and are not adulterants at all, since they come from the plant and the processing, but they cause false positives with marquis and liebermann.
Then a small tail that is not small in consequence: 11 samples contained heroin, 6-MAM or acetylcodeine, and nobody at that party is expecting an opioid.
False positives from coca alkaloids
Step 1, confirm it is cocaine
Six reagents, each ruling out a different family. Morris confirms the presence of cocaine. Liebermann excludes phenacetin, ephedrine, lidocaine, levamisole, methamphetamine, cathinones and coca alkaloids. Mecke excludes lidocaine, cathinones and various stimulants. Simon's excludes MDMA, methamphetamine, PMMA, cathinones and partly levamisole. Robadope excludes 2C-x, amphetamine, MDA, PMA and taurine. Ehrlich excludes benzocaine, procaine and tetracaine. Two readings are worth memorising: marquis should not react at all with pure cocaine, and liebermann should stay yellow, because orange indicates coca alkaloids.
Single-use cocaine test, 3.65 EUR · Cocaine and cuts kit, 31.4 EUR · Cocaine purity and identification, 102.48 EUR · Full method
Step 2, find out what else is in there
Reagents indicate presence and cannot count. A TLC purity test separates the sample and shows every compound in it as a separate spot, including the ones no reagent reacts with, and against a calibrated reference it estimates how much of each. Cocaine is one of the five compounds with a lab-verified percentage curve. If nothing but cocaine appears and the sample dissolved fully, that result is consistent with a pure sample, which is the only way to get an absence result at home. The plate measures and the reagent kit names, so the two are designed to be used together.
TLC purity kit · How a TLC test works
Step 3, measure the strength
A quantity test estimates concentration in a sample where cocaine has already been identified, which is why step 1 comes first. Give a quantity reagent a sample full of procaine and it will produce a colour quite happily, and you will read a number that describes the wrong compound.
PRO Test for Cocaine Quantity, 8.52 EUR · EZ Test for Cocaine Quantity, 11.93 EUR
Purity and quantity are not the same word
A purity test asks what fraction of the powder is cocaine. A quantity test asks how much cocaine is in the line you are about to do. Related, but 90% purity in a 200 mg line and 90% purity in a 60 mg line are the same purity and very different evenings. If you only ever run one of the two, we would run the purity test, because it also catches the levamisole.
Cocaine test kit · TLC purity kit
Questions?
Does the numbing test work?
No. Local anaesthetics were found in 108 of 767 samples, and procaine, lidocaine, benzocaine and tetracaine all numb. Numbing indicates a local anaesthetic is present, and nothing else.
What is the average purity of cocaine in Europe?
Across 523 lab-tested samples, median 86% and mean 78%. Those are samples a lab had already confirmed were cocaine, so the figure is a reason to run a quantity test rather than assume a familiar dose, not a reason to skip the reagents that establish what you have.
Is levamisole common?
61 detections in 767 samples, plus 17 of tetramisole. No reagent identifies it directly; liebermann and simon's help exclude it, and TLC shows it as a spot.
Can a reagent tell me the percentage?
No. Reagents indicate presence, not quantity. Percentage needs TLC against a calibrated reference, or a laboratory.
Which test if I only buy one?
The cocaine test kit. Identification is the question that invalidates every other answer, and it is the cheapest to answer.
Why did marquis react when I have good cocaine?
Marquis should not react with pure cocaine. A pink or peach change suggests secondary coca alkaloids, which also turn liebermann orange.