CBD(A) (in)solubility in water – results of experiment

So-called “hemp teas” have been available to Polish consumer for a long time now. Said “teas” are basically dried green parts of industrial hemp (cannabis sativa sativa). Taking into account the characteristics of industrial strain of cannabis, one cannot help but wonder – does preparing such infusions actually make sense? Since it is well known that cannabinoids are hardly water-soluble, is it possible for those precious ingredients to be extracted into the beverage? Although there is a paper addressing such problem (Arno Hazekamp: Cannabis tea revisited: A systematic evaluation of the cannabinoid composition of cannabis tea), it deals exclusively with THC and as such it won’t satisfy curiosity of the reader concerned specifically with industrial hemp (which, needless to remind, contains only a very low level of THC).

Our research team has set out to investigate the problem by conducting a series of experiments. The basic matters addressed were: whether (and in what amount) cannabinoids can be extracted by water solution and whether and how the amount of dried mass used and the duration of the infusing process itself influence the cannabinoids levels in the final infusion.

For the purpose of experiment dried mass from the last year’s harvest was used, a sample containing a relative high (for the industrial strain) level of cannabinoids. The input material has been grinded evenly in order to guarantee the same average characteristics of every sample. The exact levels of the investigated substances in the input material has been provided in the table no. 1

SubstanceCBDCBDATHCTHCA
Content in dried mass [%]0,372,220,050,11

The first experiment set out to specify the optimal time of brewing, it is to said – the time that would guarantee the highest possible level of cannabinoids in the final infusion. Proceedings were as follows: 1l of water has been poured into the metal container and boiled under the lid. As soon as the water had started to boil, 5g of the dried hemp mass has been added and the container was heated furtherly. In precise time intervals the samples were collected and investigated with HPLC (high-performance liquid chromatography) technique. The results are provided in the table no. 2

TimeAmount retrieved [%]Amount in 200ml [mg]
[min]CBDCBDATHCTHCACBDCBDATHCTHCA
50,6563,0210,0212,40,020,2
100,8544,0180,0312,00,020,2
151,0533,5160,0411,80,020,2

Table 2 displays the results using the measure of retrieval rate – the percentage of the initial levels of cannabinoids preserved after brewing, and the absolute amount of the them in the glass (200ml) of the infusion. It shows clearly that the highest levels were observed in the first examination (after 5 minutes). Among the four investigated cannabinoids, CBDA is the easiest one to extract – after five minutes of brewing more than the half of its initial level in the dried mass sample could be found in the infusion. What is interesting, though, is that the longer the brewing lasted, the lower were the levels of CBDA in the infusion. The logical explanation was that in the high temperature acidic CBDA would transform into the neutral CBD, yet nothing like this has happened. After one hour the level of 50% of the released CBDA plummeted to 33% of the original amount – although 17% of CBDA degraded, the CBD level increased by only 0,5% (of the original mass in the dried input). The most possible explanation is that the remaining amount of CBDA decayed. Similar effect can be observed in case of THCA – after 5 minutes a little over 20% was obtained, and after one hour only 3% of the original amount remained in the infusion. Again, as with CBDA, no significant rise in the THC level was observed.


In the next experiment the relation between the amount of the input mass and the cannabinoid levels in the infusion was investigated. Based on the previous observations, the infusions with 5, 10 and 20 grams of dried per 1 liter were prepared and brewed for 5 minutes. The results of the experiment are provided below in Table no.3

Input mass [g]
for 1l of water
Amount retrieved [%]Amount in 200ml [mg]
CBDCBDATHCTHCACBDCBDATHCTHCA
50,6563,020,60,012,40,020,2
101,0322,911,40,114,20,030,3
152,1202,25,40,317,70,040,2

As expected, the higher the initial mass of the dried input, the higher the final cannabinoids content in the “tea”. However, it is worth noting that even though the input mass has doubled (from 5 to 10g/l), the rise in the cannabinoids levels hardly reflected it – for instance, the efficiency of the extraction process decreased from 56% to 32% and 20% (respectively with 10 and 15 grams of the input). It is clear that increasing the amount of the input mass can ony slightly increase the cannabinoids’ levels. What is interesting here is that the percentage content of CBD as compared to its content in input sample rose significantly (from 0,6% to 2,1%), the fact that can be probably explained with this form’s very weak solubility in water.

After analysing the results of the experiment the following conclusions can be drawn:

  • it is indeed possible to obtain an infusion containing CBDA in satisfying amount of around 12mg per glass (200ml) – provided that the “tea” is prepared with 5grams of good quality (min. 2% CBDA) / 1liter, and the infusion is brewed for no longer than 5 minutes
  • conversion of acidic forms (CBDA, THCA) to neutral ones (CBD, THC) hasn’t been observed
  • brewing for longer than 5 minutes will result in gradual degradation of the cannabinoids
  • the crucial requirement to obtain satisfying levels of CBDA in the “tea” is its relatively high level in the input material; here we face another problem – the level in question is often not disclosed, or even faked by the vendor
  • due to cannabinoids’ limited solubility the solution reaches the point of saturation quite fast, therefore increasing the amount of the initial input in hope of obtaining more saturated brew is actually waste of the input material
  • as proven above cannabis “tea” contains mostly CBDA, cannabinoid far less potent than its neutral form CBD
  • the taste of “tea” prepared with 5g/l input rate is very intense, rather acceptable only for connoisseurs, to say the least
  • one glass of infusion contains similar amounts of canabinoids as just a few drops of oil (depending on its concentration), the fact thact helps to realize how much less efficient are the water-based solutions

EFERENCES

1. Hazekamp, Arno, et al Cannabis tea revisited: A systematic evaluation of the cannabinoid composition of cannabis tea. Journal of Ethnopharmacology. 2007, 113, pp. 85 – 90.

Dr. Jarosław Szufler
Translation Robert Kania