One of the cannabis marketplace’s current blossoming love affairs is with color remediation chromatography (CRC).
Actually, somewhat of a misnomer, in that chromatography simply separates the constituents of a feed stream, by eluding them at different rates, they don’t just remove color.
It is easy to see it from the color remediation perspective, if you consider that most of the color in an extract is from longer heavier molecule like b-Carotene and pheophytin, or polar elements like the C-15 anthocyanin glucoside/flavonoids. All of the C-10 and C-15 terpenes, as well as the C-22 cannabinoids in cannabis, are colorless to light yellow.
Reference 8.1 Sweet Mary’s Charms, by JD Ellis and Rob Brown:
In reflecting on what sorts of articles to reopening The Alchemist Research with, that would be appealing to my traditional readership, CRC was one of the things on my list.
Imagine my joy and amazement when friend and associate Jay Romano, of Apis Labs in Eugene, invited me to an after-event party in Springfield, that he was hosting at The Starship, following Murphy Murri’s CRC class at Capital Cannabis.
Imagine me grinning ear to ear when Murphy gave me permission to audit her class for free, even though all the tickets were long since sold out. Such a deal!
Also a pleasure to visit the Capital Cannabis facility, which was done right, presenting a clean and easy to clean workplace, as well as a first class extraction booth with proper ventilation for the extraction and chromatography operations that Murphy demonstrated.
Getting ready for class at Capital Cannabis
Murphy is an enthusiastic animated speaker, who conveyed her points in a cogent understandable fashion, as well as answered questions and fielded hard balls from corner field.
Murphy is an enthusiastic and animated speaker.
She kept her audience engaged and both told and showed us how to perform the process using a column designed and built by NB Oler and adsorbents by Carbon Chemistry.
NB Oler CRC Column
As you can see, the NB Oiler CRC column breaks down in sections. The first section has view ports to allow you to monitor the feed material, followed by a filter assembly, the reservoir, another filter section, the chromatography column itself, more filtration, and the final chamber where the discharge flow can be monitored through view ports.
As the system operates with LPG, it is required to meet not only ASME Section VIII, and NFPA 058, so the clamps are either MP 13, or SSH to meet pressure requirements, and the view port wafers appear to be Metaglas.
Valves are Swagelok and it has the mandatory PRV in the top.
In practice the way the column works, is that an adsorbent mixture is packed into the chromatography column and the upper reservoir flooded first with a clean LPG mix, to above the top sintered filter plate, and drained through the packed column to wet it. It is plumbed from the bottom of the column into a recovery vessel, from which the LPG can be recovered as vapor and returned to the clean LPG tank as a liquid.
That is followed by the stream of LPG containing the solute that you wish separated, which separates as it makes its way through the packed column bed, and the constituents flows out the bottom of the column at different rates, where they can be drawn off as fractions.
To pack the column, it is first removed from the assembly by removing the bottom section, and then dropping the upper and lower filter assemblies, with the chromatography column as one unit.
Upper and lower filter assemblies, with jacketed chromatography column between.
Both filter assemblies are removed and a 20 micron #41 lab filter trimmed to size and added as a prefilter for the lower sintered stainless final filter, before returning the unit to the bottom of the column. It is then covered with plastic retained by a rubber band to keep the lower assembly dust free.
Much of Murphy’s presentation was regarding safety, pointing out that loading the columns requires both eye and respiratory protection, as well as dedicated clothing, in an isolated location away from the rest of the operation, to keep the fine dust from spreading throughout the shop.
Murphy used Silica gel, T-5 Benzonite clay, and a T-41mixture of Benzonite clay and carbon as her column media, which she first baked out in Capital Cannabis AI ovens, using heat and no vacuum. In that process, the volatiles forced out of the media formed a darker coat on the top surface, which she skimmed off before using, to get to the clean media below.
After skimming, she carefully weighed out enough media to fill the column, plus a little, and thoroughly mixed it in a bucket, before transferring it to the column.
Mixing the adsorbent media using personal protection equipment.
After loading the mixed media into the column, another #41 paper filter is placed on top, held in place by a perforated plate, itself held down by two stainless rings. The final filter assembly is clamped on top to hold the stainless rings in place, after they are carefully tamped into place using a soft mallet, and all surfaces carefully cleaned of dust.
The final assembly is then inserted into the column and clamped into place, after which the column was moved to the extraction booth and the plumbing attached, including a hot water supply and return to the jacketed chromatography column itself.
Tamping filter plate retaining rings into place.
Column installed in extraction booth
Note the Capital Cannabis extraction booth is properly designed with the exhaust low at the back of the booth, and filtered makeup air supplied from the ceiling in the back of the booth. Exhaust rates are maintained in the comfort range unless the booths hydrocarbon detector (HC), spools up the exhaust fan to ~100 SF via variable frequency drive.
Note it is also clean and easy to keep clean, with everything on wheels besides the recovery pump.
The booth also contains a Precision Extraction closed loop extraction system and pump. A purdy thang to gaze upon and it worked slick in conjunction with the NB Oler column.
Looking at the PE cart picture, there is an unjacketed 4” extraction column on the left, and a high-pressure nitrogen bottle directly behind it.
Next comes the jacketed LPG storage/supply tank, followed by the recovery/collection vessel with a jacketed “shatter platter” on the bottom, replete with bottom discharge valve.
Both the chromatography column and the recovery tank jackets were plumbed for heat, and as you can see from the condensation on the LPG supply tank that it is on a chiller.
In both applications, heat is not applied to raise the temperature of the process, it is added to counterbalance the refrigeration effects of the processes.
Nitrogen from the bottle in the rear of the booth are used to add head pressure to the subzero LPG supply tank when required to provide enough pressure to push the LPG mixture through the extraction column and to the CRC column.
After evacuating the system, Murphy flushed the CRC column clean LPG and that LPG was plumbed to the PE recovery/collection vessel, where the LPG was pumped off as a vapor and condensed as a liquid back into the storage/supply tank.
She then removed the shatter platter and meticulously cleaned it, before replacing it for the CRC run, during which time a partial sock of pre-prepared cannabis material was loaded into the PE column and then both were evacuated.
The system was plumbed so that the discharge from the PE column was diverted to pass through the CRC column, in route to the PE collection vessel.
While the process was monitored via the lower sight glasses, it was in the shatter platter that the magic happening in the CRC column became apparent.
Murphy periodically shut off the stream to the shatter platter and recovered the LPG, leaving the fraction that was coming over from the CRC column with the LPG. She then drained off those fractions through the valve in the bottom into separate jars.
Drawing fractions
First to come over were the lighter monoterpene fractions, which she passed around for us’n to sniff. Everything eventually comes through in its own time, and each fraction can be saved in isolation, mixed with other fractions, or tossed, depending on its nature and utility.