54 February / March 2018
Table 2: Detailed extraction mass balance data for six hemp extractions. Cannabis assays were performed by ProVerde Laboratories and Mass balance calculations were performed using Waters Bio-Botanical Mass Balance Calculators at
www.waters.com/massbalance
Extraction Number
1 2 3 4 5 6
Standard Dev.
Starting Mass (g)
1746 1664
1564.5 1589 1474
1383.46
Mass Extract CS1 (g)
50.99 28.94 27.19 20.98 9.11 6.50
Average 1570.16 23.95 129.78
16.13
Mass Extract CS2 (g)
75.95 94.39 92.38 95.02 88.31 80.24 87.72
7.93
Six replicate extractions were performed using Waters Bio-Botanical Extraction System (Figure 4, Figure 5). A total of 670 g raw extract (7.11 wt% Total Mass Yield) was generated from the 20 pound hemp feedstock. Three distinct extract fractions,
Total Mass
Yield (g) 126.94
123.33 119.57 116.00 97.42 86.74
111.67 15.97
wt% Cannabinoid Starting Material
5.04 5.04 5.04 5.04 5.04 5.04
wt% Total Cannabinoid Extract CS1
67.67 59.13 61.03 60.14 54.89 53.51 59.40
5.03
one from each cyclone separator (CS 1-3), were collected from each extraction (Figure 6). CS 1 fraction was homogenised and analysed and CS 2 and 3 fractions were combined, homogenised, and analysed as a single fraction. Aggressive extraction
wt% Total Cannabinoid Extract CS2
50.79 50.92 51.92 52.03 58.11 55.89 53.28
3.01
wt% Acidic Cannabinoid CS1
62.32 55.86 58.44 57.49 53.55 52.00 56.61
3.68
wt% Acidic Cannabinoid CS2
40.63 43.48 44.01 43.88 49.58 48.00 44.93
3.28 Percent
Cannabinoid Yield
91.38 87.71 90.77 85.93 82.73 80.34 86.48
4.38
conditions were utilised in this study (Table 1). Approximately 1,600 g of plant material was packed into a 5 L extraction vessel and extracted for 210 minutes at 344 bar and 55ºC. An average of 86% (SD=4%) of the available cannabinoids were extracted and collected (Table 2). Extract was drained from the cyclone separators every 30 minutes and stored in a refrigerator until analysis. For each extraction, five samples were submitted for analytical testing: the hemp feedstock for that batch, extract fraction 1, extract fraction 2, ethanol rinse, and raffinate; a detailed mass balance was performed for each extraction (Table 2). Effluent CO2
was collected and recycled;
approximately 2.5 full extractions were performed per 50 lb tank of CO2
extractions. Discussion:
Figure 4: Waters Bio-Botanical Extraction System (BBES). The pumps are on the bottom, 5 L extraction vessels to the left, and three 2 L cyclone separators at the top right.
Six replicate extractions were performed over the course of 3 weeks. Significant variability in the amount of material loaded in the 5L vessel was observed, with a standard deviation of 130g of raw bio-botanical plant material (Table 2). As a result, inconsistencies in the total mass of extract collected were observed, ranging from 86.7g to 126.9g. The mass collected in each collection vessel is shown in Table 2, and Figure 7. The total cannabinoid yield under the CO2
conditions employed was
more consistent ranging from 80% to 91% (SD 4.4%) (Table 2, Figure 8). Still, there was a consistent decrease in both the amount of material loaded into the extraction vessel and the cannabinoid percent yield; this means the extraction was less efficient with less material loaded in the extraction vessel. This result is surprising because the amount of solvent used per gram of hemp is greater when less material is
Figure 5: BBES block diagram. System flow is from the left to the right. . The entire
system, with the exception of the CO2 recycler, was vented and cleaned between
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