# Study of the Kinetics of Extraction Process for The Production of Hemp Inflorescences Extracts by Means of Conventional Maceration (CM) and Rapid Solid-Liquid Dynamic Extraction (RSLDE)

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## Abstract

**:**

## 1. Introduction

## 2. Material and Methods

#### 2.1. Samples

#### 2.2. Materials and Solvents

#### 2.3. Extraction Process by Conventional Maceration (CME)

#### 2.4. Cyclically Pressurized Extraction (CPE) Process (Rapid Solid-Liquid Dynamic Extraction (RSLDE)

#### 2.5. Determination of Solid Matrix Pieces Size

#### 2.6. Determination of the Total Volume

#### 2.7. Determination of the Initial Concentration of the Solid Matrix

#### 2.8. HPLC Analysis

_{2}O and solvent B 0.1% TFA in acetonitrile (ACN). The gradient was: 20% A for 3 min.; 100% B at 20 min; hold for 5 min. The run had a total duration of 20 min and the flow rate was set at 1mL/min. Cannabinoids were detected at a wavelength of 215 nm. The trueness and precision of the HPLC method used were assessed by analyzing a standard sample of hemp inflorescences (Dietalinea, Società Agricola Eatruscan srl, Cesena (FC), Emilia-Romagna, Italy) for which all cannabinoids (CBDA, CBD, THCA and THC) were quantified and certified. Standard inflorescences were undergone to CME and CPE extraction procedures and alcoholic extracts of cannabinoids obtained were analyzed by HPLC under the same chromatographic conditions. These two procedures were repeated three times and the standard deviations for the cannabinoids analyzed were less than 3% for THC and CBD, while they were less than 2% for THCA and CBDA in both cases. Moreover, the results of analyses of alcoholic extracts obtained with CME and CPE procedures of extraction give good results for trueness; deviations for all cannabinoids (CBDA, CBD, THCA and THC) in respect of certified values analysed were less than 3% for both procedures of extraction.

#### 2.9. Dry Residue

#### 2.10. Analytical Approach

_{e}= f

_{e}

^{2}× D

#### 2.11. Finite Element Method Approach for CPE Process

_{i}= concentration of the solute -i-

^{2}/s for the solute extracted, S.

^{3}(The relative activities of each fraction were determined on the basis of molar concentration (mol/L) or mass concentration (g/L).

#### 2.12. Statistical Analysis

## 3. Results and Discussion

#### 3.1. Drying

_{2}, leading to the formation of active cannabinoids (CBD and THC). Table 1 shows the data of the various drying tests, with variable time and temperature.

#### 3.2. Kinetics Diagrams of CME and CPE Processes

#### 3.3. Dry Residue

#### 3.4. HPLC Analysis

#### 3.5. Cyclically Pressurized Extraction (CPE) Process

^{−10}to 2.376 × 10

^{−10}m

^{2}/s.

^{−11}to 1.35 × 10

^{−10}m

^{2}s

^{−1}between 25 and 90 °C [27], and Linares et al. (2010) estimated this coefficient for yerba mate aqueous extraction kinetics, ranging between 6.092 × 10

^{−11}and 9.469 × 10

^{−11}[28].

#### 3.6. Numerical Analysis

## 4. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 2.**Kinetics diagrams for the extraction processes: conventional maceration extraction process (CME) and cyclically pressurized extraction process (CPE), with error bars.

**Figure 4.**High-performance liquid chromatography (HPLC) analysis of a pre decarboxylation hemp extract. (x-axis: time in minutes; y-axis: mAU).

**Figure 5.**HPLC analysis of a post decarboxylation hemp extract (x-axis: time in minutes; y-axis: mAU).

**Figure 6.**(

**a**–

**h**) show a gradual migration of the extracted solute from the centre of the solid matrix to the surface. (

**a**) Concentration values at time t = 30 min. (

**b**) Concentration values at time t = 60 min. (

**c**) Concentration values at time t = 90 min. (

**d**) Concentration values at time t = 120 min. (

**e**) Concentration values at time t = 150 min. (

**f**) Concentration values at time t = 180 min. (

**g**) Concentration values at time t = 210 min. (

**h**) Concentration values at time t = 240 min. Theoretically, the finite element model, as shown in Figure 6a–h, indicates that even at the end of the extraction process, the concentration throughout the solid matrix is not uniform.

n. | Grams of Hemp at t = 0 | Grams of Hemp at t = 1 | T° | Time | % Grams Lost |
---|---|---|---|---|---|

1 | 45.1619 | 39.8500 | 110 °C | 15 | 11.76 |

2 | 45.1474 | 40.0400 | 110 °C | 16 | 11.31 |

3 | 45.0302 | 39.9800 | 110 °C | 20 | 11.21 |

4 | 46.6100 | 41.3510 | 110 °C | 22 | 11.28 |

5 | 45.2654 | 40.2468 | 120 °C | 15 | 11.08 |

6 | 45.5648 | 39.7742 | 120 °C | 16 | 12.70 |

7 | 45.0396 | 39.4000 | 120 °C | 20 | 12.52 |

n. | Liquid Sample | Dry Sample | Dry Residue % |
---|---|---|---|

1 | 3.7875 | 0.0249 | 0.66 |

2 | 4.0039 | 0.0277 | 0.69 |

3 | 4.0221 | 0.035 | 0.87 |

4 | 3.8434 | 0.0269 | 0.7 |

5 | 3.9221 | 0.03 | 0.76 |

6 | 4.0285 | 0.0339 | 0.85 |

7 | 4.0132 | 0.032 | 0.79 |

n. | %CBDA | %CBD | %THCA | %THC |
---|---|---|---|---|

1 | 14.84 | 2.30 | 0% | <0.6% |

2 | 13.48 | 2.82 | 0% | <0.6% |

3 | 12.35 | 3.30 | 0% | <0.6% |

4 | 12.23 | 3.36 | 0% | <0.6% |

5 | 8.61 | 2.92 | 0% | <0.6% |

6 | 8.60 | 4.41 | 0% | <0.6% |

7 | 7.58 | 4.71 | 0% | <0.6% |

**Table 4.**The physical characteristics of the solid matrix particles measured during the CPE process.

Minutes | L1 Length (mm) | L2 Width (mm) | L3 Thickness (mm) | f_{e} | |
---|---|---|---|---|---|

1 | 6.05 ± 0.81 | 5.22 ± 0.78 | 4.51 ± 0.80 | 0.986756 | 1.003385 |

60 | 6.01 ± 0.78 | 5.01 ± 0.61 | 4.49 ± 0.78 | 0.984958 | 1.012366 |

90 | 5.93 ± 0.69 | 4.98 ± 0.71 | 4.46 ± 0.65 | 0.985755 | 1.01131 |

120 | 5.9 ± 0.68 | 4.95 ± 0.75 | 4.43 ± 0.69 | 0.985606 | 1.011373 |

150 | 5.86 ± 0.70 | 4.93 ± 0.69 | 4.4 ± 0.74 | 0.985761 | 1.010711 |

180 | 5.84 ± 0.67 | 4.90 ± 0.65 | 4.36 ± 0.60 | 0.985288 | 1.010752 |

210 | 5.81 ± 0.65 | 4.86 ± 0.64 | 4.33 ± 0.62 | 0.985015 | 1.011309 |

240 | 5.78 ± 0.72 | 4.83 ± 0.70 | 4.29 ± 0.66 | 0.984722 | 1.011117 |

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**MDPI and ACS Style**

Gallo, M.; Formato, A.; Ciaravolo, M.; Formato, G.; Naviglio, D.
Study of the Kinetics of Extraction Process for The Production of Hemp Inflorescences Extracts by Means of Conventional Maceration (CM) and Rapid Solid-Liquid Dynamic Extraction (RSLDE). *Separations* **2020**, *7*, 20.
https://doi.org/10.3390/separations7020020

**AMA Style**

Gallo M, Formato A, Ciaravolo M, Formato G, Naviglio D.
Study of the Kinetics of Extraction Process for The Production of Hemp Inflorescences Extracts by Means of Conventional Maceration (CM) and Rapid Solid-Liquid Dynamic Extraction (RSLDE). *Separations*. 2020; 7(2):20.
https://doi.org/10.3390/separations7020020

**Chicago/Turabian Style**

Gallo, Monica, Andrea Formato, Martina Ciaravolo, Gaetano Formato, and Daniele Naviglio.
2020. "Study of the Kinetics of Extraction Process for The Production of Hemp Inflorescences Extracts by Means of Conventional Maceration (CM) and Rapid Solid-Liquid Dynamic Extraction (RSLDE)" *Separations* 7, no. 2: 20.
https://doi.org/10.3390/separations7020020