All cannabis users are familiar with the innumerable comparisons when it comes to the THC content of their own flowers: the best and strongest haze – “definitely 30 percent THC” – yet still you don’t get high enough? The truth is, nobody can tell you exactly how much THC there is in the blossoms, unless you know a laboratory where you can send in samples anonymously and have them analyzed. But it’s not that easy after all, at least if you live in Germany versus California. So wouldn’t it be great if you could also use an equally effective method privately, a mobile laboratory, so to speak? For this purpose we take a look at the Purpl PRO, which is now also available in Germany. The device is now used in the cannabis industry worldwide and is known to many enthusiasts. The Purpl PRO can easily be connected to an iOS or Android smartphone via Bluetooth, and this connection provides you with a state-of-the-art cannabis potency measurement system. But does the device really work accurately? And how does it even work?
An article by Ico De Niroll. Originally published in Highway Magazine. Article has been translated to English with slight corrections made.
The Purpl PRO is a robust and pocket-sized THC and CBD screening device with an unlimited number of tests that is capable of delivering results in less than ten seconds. The device can measure CBD content between two and 15 percent, with THC’s maximum of 30 percent can be determined. This upper limit will be increased over time, when new strains with higher concentrations will become available area-wide. Extract measurements are also planned for the future. Potency measurements can currently be carried out with cannabis flowers – as often as you want and without damaging the sample (apart from grinding). This can be consumed directly afterwards. It is very easy to use: First, you download the Purpl PRO app and create an account. Then you connect your smartphone to the device via Bluetooth, register it and you’re ready to go. The first thing to do is to calibrate the device. In order to do this, place the Purpl PRO top down over the calibration puck.
This calibration puck is critical to proper operation. It is used to prepare and initiate the optical sensors. The white material of the puck has been specially made to reflect every color equally. For this reason, you should always make sure that the calibration puck is not dirty. Then you take the device and attach the so-called sample holder. The sample holder is used to position the flower sample optimally over the measuring window. A funnel cap has been specially designed for the SLX-Grinder so that the sample can be introduced into the sample holder as easily as possible and without losses.
For measurements, you need approx. 0.8 grams of flower material, which can still be used normally after testing. After filling with flower, you close the cap of the sample holder and press on your smartphone, “Measure now”. The result is available within seconds. If desired, this can be saved in a database, notes can be made or the exact course of several measurements can be tracked. At the end of 2020, an optional upgrade was released with the “+ H20-Pack”, which enables users of the Purpl PRO to add measurements of moisture content and water activity to their test results. Traditional methods of measuring moisture and water activity are cumbersome, time consuming, and costly.
With the Purpl PRO, these measurements can be carried out in a blink of an eye, also without making the sample unusable. In this way, users can determine the best time for harvest or market launch, gain important information about the product composition, better control mold and fungal attacks, and be positioned optimally to achieve the highest possible quality.
Development and Sales
Purpl Scientific is a United States-based technology company dedicated to providing accurate, affordable tools that provide insight and information about products and potencies. The Purpl PRO development team is based in Finland, the birthplace of the cell phone industry. The Purpl PRO entered the market in 2019, with the focus on North America at first.
“The Purpl PRO is backed by technology that’s been used in the agricultural, pharmaceutical, and food and beverage industries for years. We’re proud of our ability to offer this level of technology at an affordable price point; it’s a key factor in our mission to reduce the guesswork around the potency and quality of cannabis products, from cultivation to consumption,” President Chad Lieber said.
A main goal for 2020 was to increase Purpl PRO’s representation in the fast growing European markets. A partnership with Delta 9 Analytics from the Netherlands, who have taken over European sales, has driven this forward to a great extent.
“We are proud to sell the Purpl PRO all over Europe. This industry-changing instrument will bring transparency to the entire continent,” reveals Olaf van Lonkhuizen, who founded Delta 9 Analytics together with his brother Flynn.
In the Netherlands in particular, they support coffee shop operators who are currently having a major problem purchasing their goods. Many owners report how CBD flower is spreading in shops and experiencing an increasing problem of synthetic cannabis being sprayed onto the flower. All of this is mainly due to the fact that you cannot maintain decent quality control. This is related to the current legal situation in the Netherlands. The cultivation of cannabis in the Netherlands is officially illegal, and so coffee shop owners mostly have to buy their stocks from dealers who secretly grow indoor or outdoor in the open air, always in danger of the Dutch judiciary deciding to raid. Official analyses in a laboratory are therefore not that easy or very expensive.
This is one of the reasons why the two brothers from the Netherlands offer a try-out service for their coffee shop customers. In this way, dealers can gain initial insights and, ideally, be convinced of the results directly.
In order to keep bad or even harmful cannabis flowers away from the shops and the street, more emphasis should be put on control. This is where the Purpl PRO and its easy-to-use technology can score and bring all users an advantage when it comes to the quality of flowers or their own plants.
Delta 9 Analytics itself did not have its own sales shop last year and was able to sell over one hundred of these 1,995 euro devices to satisfied customers. So far, this has all been done via social media and the support of customers who report on the Purpl PRO and share their results with other interested parties. But that should become more professional this year, because the two brothers have other projects going on, which we will definitely be reporting on in the future.
“There are more products to come in our portfolio that are related to the quality control of cannabis flowers, including a portable microscope and a new test kit to identify synthetic cannabinoids, thus solving the problems of consumers and traders. We would like to make a contribution to the education,” says Olaf van Lonkhuizen from Delta 9 Analytics.
Who Are the Users of the Purpl PRO?
Checking your flowers on a daily basis can become an important element for one or the other in the cannabis community without having to send samples to a laboratory, but it should be noted that most states only use gas chromatography or high pressure liquid chromatography for legal commercial activities accept certified methods – more on that later.
Regardless, the Purpl PRO is ideally suited if a potency measurement is to be carried out for which no third-party laboratory tests are required, or the in-depth quality is to be checked. Basically, it is suitable for everyone, whether private or commercial, simply for yourself or for the presentation of your own flowers. Thus, the device has already come into the focus of end consumers, after all, they would like to know what they are getting and smoking. Is it THC or did you get CBD?
Knowing the exact effectiveness is ultimately also the key to an appropriate dosage. It is also important for suppliers and pharmacists to know how ingredients have changed since the first inspection. You need an instant insight into its effectiveness and composition. The Purpl PRO can deliver it. By instantly measuring the cannabinoids, traders can check the values within a batch or the measurement up to the last batch and confirm the quality.
The device is particularly suitable and exciting for the process in which it all begins: the cultivation. The Purpl PRO is based on the same technology used in agriculture (and pharmaceutical) to instantly provide chemical information that helps optimize the harvest. Incidentally, a representative composite sample is obtained if you take parts of the plant from above, from the middle and from below. It is also advisable to sample different plants to find out whether there are any differences in the breeding system.
“Thus, our products reduce the puzzle and the mere assumption of effectiveness, quality and chemical composition during the entire life cycle, from cultivation to consumption. We are an advanced technology organization that prides itself on simplifying complexity,” said Lieber.
Over 150,000 tests have already been carried out with the Purpl PRO worldwide. The data is automatically sent to the server, evaluated there, and made available to each user any time through the Purpl Portal.
Measured Values Thanks to NIR Spectroscopy
So, how does it all work? The Purpl PRO uses near-infrared spectroscopy to determine the cannabinoid values, in which light is directed onto the sample and the returned light is analyzed. Covalent molecular bonds in (mostly) organic compounds are stimulated by means of infrared radiation. The identification takes place in the near infrared (NIR), in this part of the light spectrum molecules react to certain areas of the light in order to create a “molecular fingerprint” that can be correlated with the concentration. For quantitative determinations, data sets with a known content of the substance to be determined are created beforehand, more on this below. There is a near-infrared spectrometer in every Purpl PRO.
Put simply, a spectrometer measures the intensity of different colors of light. Strictly speaking, “color” refers to an area of light that humans can see, but different spectrometers can detect and measure all types of light, including what the human eye cannot see. And we humans cannot see what really cool things happen in this light – different “colors” of light change when they hit certain molecules. THC molecules absorb some light at certain points in the NIR (the light is redder than our naked eyes can see). When there is more THC, it absorbs more light. When there is less THC, it absorbs less light. Based on near-infrared spectroscopy, a technology originally developed for agricultural measurements 70 years ago and currently used in nearly every industry to test multiple product attributes instantly, the Purpl PRO aims to bring this proven approach to the cannabis industry.
The state of the art in potency tests is laboratory analysis of representative samples of cannabis products, either using gas chromatography (GC) or high pressure liquid chromatography (HPLC). However, both techniques require costly instrumentation, trained technical operators, and frequent maintenance and calibration to achieve consistent results. This complexity and cost has led to potency tests that cost hundreds of dollars each and are performed in outside laboratories with turnaround times of days or weeks. Both GC, HPLC, and NIR spectroscopy provide results based on estimates. HPLC uses chemical reference standards for this purpose, for example, while NIR spectroscopy is correlated to these HPLC values. Discrepancies between HPLC results are common. Results are subject to the analytical method used, instrument calibration, sample preparation, operator skill, and interpretation of results. Consequently, HPLC performance is subject to human error.
How Accurate is the Purpl PRO?
According to the manufacturer, the sensors were subjected to HPLC measurements during initial calibration in two certified laboratories in California and Oregon. For this purpose, a total of 204 cured flower samples were analyzed. Each sample was ground and mixed in a conical tube for better homogenization and then distributed to eight Purpl-PRO sensors. The sensors recorded at least four and up to 30 near-infrared spectra from each sample. Samples were rotated over the sensors so that each sample aliquot could be evaluated on all sensors. A total of 35,293 near-infrared spectra were thus made. After near-infrared scanning, the remnants of each flower sample were recombined in a separate conical tube and mixed for homogenization. These samples were then analyzed by a cannabis testing laboratory using HPLC.
The accuracy of the Purpl PRO is in the range of +/- 2 percent, statistically it is +/- 1.89 percent for THC and +/- 0.96 percent for CBD. The mean absolute error (MAE) of the moisture prediction of the +H20 pack, for whose initial calibration a total of 55 flower samples were analyzed, yielding 10,926 date sets, is 2.4 percent. For the critical range of 10 to 20 percent moisture, the MAE is 1.5 percent.
These prediction errors are comparable to those reported for laboratory LOD analysis of cannabis samples. The MAE of water activity prediction based on both calibration and validation data sets is 0.02 percent. As with moisture prediction, these errors are comparable to those reported for laboratory water activity analysis.
The quality of (medical) cannabis can vary widely. This often creates uncertainty for consumers/patients and their sellers or prescribers. The composition and concentration of the ingredients are influenced by numerous factors. Cannabis is a heterogeneous natural product. The variance between two or more flowers, even from the same plant, can be significant. Therefore, there may be variations from batch to batch. (For the cannabinoids of German pharmacy weed, a tolerance of +/- 10 percent of the value stated on the label is allowed – so if 20 percent THC is stated, the cannabis may have THC values between 18 and 22 percent). When testing, therefore, there are a few things you should always keep in mind to avoid cross-contamination of individual samples. This includes the thorough cleaning of the supplied SLX grinder, the sample holder and of course, the sensor using alcohol pads or similar. Proper grinding of the flower sample is equally important to allow for proper homogenization of the sample. In addition, one should separate flowers from stems and be on the lookout for seeds that can affect measurements. Also, one should take notes on what condition the flowers are in during the measurements. Furthermore, one should make several measurements to be able to determine an accurate average value.
Although the Purpl PRO is aimed more at growers and retailers, we end consumers from the Highway editorial team were of course still very interested and excited by the idea when we first heard about it. We were kindly provided with a testing device, and of course, some measurements were taken right away. All results seemed absolutely plausible: the CBD weed contained a lot of CBD and hardly any THC, the weak guerrilla grow weed had seven percent THC, the slightly better one 11 percent, industrial weed 18 percent, and the stuff that makes everyone super dense 24 percent, and so on and so forth. Several tests of different flowers and plants were all within the absolutely realistic range.
To learn more and benefit from a wealth of experience with the Purpl PRO, we then turned to the “Cannabis Medic Forum” (see below), where the robust device has already been used and discussed extensively for a year and countless measurements have already been taken. Thus, some medicinal cannabis flowers from the German pharmacy were also tested in detail with the Purpl PRO.
Overall, Cannabis Medic is very impressed: the results were always accurate and there were hardly any deviations from the stated values and none of the results did not seem realistic. Some strains were tested extensively over a longer period of time by Cannabis Medic, and then compared with the analysis certificates of the respective manufacturers.
The Forum www.cannabis-medic.de has been dealing with the topic of cannabis as medicine in Germany for more than three years now – from patients for patients and free of charge, without advertising and anonymously. Especially the topic of cost coverage by health insurance companies finds a place there for help, advice and experiences. In addition, current studies, news as well as varieties from the pharmacy are always updated and made available to the community. A total of almost 3,200 members are already registered with cannabis-medic.de and have written well over 50,000 articles. Everyone who wants to report on their experiences with medical cannabis and inform about their success or also risks and problems is welcome there. This also includes people who have suffered harm from long-term use of other medications. The forum offers the possibility of mutual support and exchange in the sense of a virtual self-help group. The admin and moderator team also consists of patients who take care of the order in the forum during their private free time and are happy to answer all members’ questions.