Table 2.
Extraction procedures followed for alkaloid extraction of species from the superfamily Dendrobatoidea. GC: Gas chromatography, LC: Liquid chromatography
| Type of sample | Solvent | Number of extraction steps | IV | IS | Reference | |
|---|---|---|---|---|---|---|
| Technique 1 (Solvent targeted extraction) | Mixture of skins or less frequently individual whole skins | Methanol (20-fold excess with weight skin) |
1. Maceration in mortar 2. Dilution in H2O 3. Extraction with chloroform (3x) 4. Evaporation 5. Dilution in hexane 6. Acidification 7. Basification 8. Extraction with chloroform (3x) 9. Addition of anhydrous Na2SO4 10. Evaporation 11. Reconstitution in methanol * Volumes employed in mL |
2 μL (GC) |
Not employed | (Daly et al. 1994c) |
|
Technique 2 (Solvent targeted extraction) |
Whole individual skin | Methanol (1 mL) |
1. Acidification 2. Evaporation 3. Dilution in H2O 4. Extraction with hexane (4x) 5. Basification with NaHCO3 6. Extraction with ethyl acetate (3x) 7. Addition of anhydrous Na2SO4 8. Evaporation 9. Reconstitution in methanol * Volumes employed in μL |
1 μL (GC) |
10 µg of ((-)-nicotine 99%, | (Saporito et al. 2010) |
| Technique 3 (Solvent untargeted extraction) | Whole individual frogs | 70% ethanol, 80% methanol (totally covering specimens) |
1. Evaporation 2. Reconstitution in chloroform (for lipophilic) or 0.05 M acetic acid (for hydrophilic alkaloids) * Volumes employed in μL |
Not specified | Not employed | (Mebs et al. 2014, 2018) |
| Technique 4 (Solvent untargeted extraction) |
Individual dorsal section skins |
Methanol (1 mL) |
1. Homogenization 2. Evaporation 3. Reconstitution in methanol and vortex 4. Centrifugation and separation * Volumes employed in μL |
2 μL (GC) 1 mL (LC) |
25 µg of D3-nicotine | (McGugan et al. 2016) |
|
Technique 5 (Solvent untargeted extraction) |
Individual dorsal section skins |
Ethanol (0.3 mL) after RNA extraction with Trizol |
1. DNA precipitation 2. Centrifugation and separation 3. Protein precipitation 4. Centrifugation and separation 5. Evaporation 6. Reconstitution in methanol:chloroform * Volumes employed in mL |
5 μL (LC) | 1 μM D3-nicotine | (Alvarez-Buylla et al. 2022) |
| Technique 6 (SPME targeted extraction) | Whole pair of skins | Solvent free procedure |
1. Homogenization in liquid nitrogen 2. Transfer to SPME vial and sampling |
SPME fiber (GC) |
Not employed | (Gonzalez et al. 2021) |
| Technique 7 (Untargeted MasSpec Pen) | In vivo | 5% EtOH in water | 1. MassSpec Pen tip was gently held in contact with the skin of the frog for < 15 s | NA | Caffeine | (Krieger et al. 2022) |
*IV = Injection volume, IS = Internal standard, *Additional note about the order of magnitude of the volumes of solvents employed in the procedure