Extraction of compounds of interest from bio-based materials

Extraction of compound(s) of interest covers a broad spectrum of applications in the laboratory and industrial field: from natural active ingredients (e.g. flavours, pigments, oils, vitamins, antioxidants, proteins, etc.) for pharmaceutical and food industry to contaminants and environmental pollutants (pesticides, polycyclic aromatic hydrocarbons – PAHs, polychlorinated biphenyls – PCBs, etc.) for environmental authorities. Bio-based or environmental materials (e.g. plant tissues, wood, soil) include various components whose interaction can cause undesired interferences and result in misinterpretations in quantitative and/or qualitative analyses.

The main purpose of extraction techniques is thus to gain analyte compounds (or more compounds of interest):

  1. in high yield;
  2. with highest purity without interferencing compounds;
  3. with low waste; and
  4. with low energy/time consumption at the same time.

In general, extraction techniques are based on a separation principle, „like dissolves like“, so for selecting an appropriate extraction system, the following conditions are crucial: solvent type, sample/solvent ratio, temperature, pressure, extraction duration and number of extraction cycles.

Common techniques use solid or semi-solid samples, so compounds of interest are dissolved into suitable solvents or more solvents in a row (solid-liquid extraction) or are proceeded in liquid form within liquid-liquid extraction. Liquid-liquid extractions are often performed to purify the analyte. However, this separation is possible only when the compound(s) of interest is soluble in a different solvent than the undesired compound(s). At the same time, those two solvents have to be mutually immiscible. The extraction procedures might be combined in sequences as a part of the purification step or to concentrate the amount to increase the analyte detectability.

More advanced techniques belong solid-phase extraction (SPE) using retention of analyte on a sorbent; accelerated-solvent extraction (ASE); ultrasound-assisted extraction (UAE); microwave-assisted extraction (MAE); enzyme-assisted extraction; and supercritical fluid extraction (SFE) by application of supercritical carbon dioxide.

The conventional solid-liquid extraction system counts the Soxhlet apparatus. A more sophisticated system that offers time-planning is an updated Soxhlet - PC-controlled extraction system fexIKA. A more time-effective system is accelerated-solvent extraction (ASE). It is an automated solid-liquid extraction system that uses 100 times higher pressure than conventional techniques and therefore enables low solvent consumption with the advantage of considerably shorter extraction time.  

 

Below are a few application examples for analytes from natural products, where ASE was applied:

Source

Analytes

Solvent

Temperature

(°C)

Static extraction time (min)

Number of extraction cycles

Reference

wild nettle (Urtica dioica L.) leaves

polyphenols, pigments

ethanol (96%)

20; 50; 80; 110

5; 10

1; 2; 3; 4

Repajić et al., 2020

sorghum bran

polyphenols, antioxidants

50 and 70% (v/v) ethanol

60; 120; 150

1

1

Barros et al., 2013

grape skin pomace

polyphenols, antioxidants

50% ethanol

50

15

2

Li et al., 2019

carrots

carotenoids, polyphenols

ethanol

40–120

20–60

1–3

Šeregelj et al., 2018

red cabbage

pigments

water/ethanol/
formic acid

80; 100; 120

1–5

1

Arapitsas and Turner, 2008

rape seeds (canola)

oil

petroleum ether

105

10

3

Kettle, n.d.

brewer's spent grain

proteins

NaOH

40; 60; 80

5; 15; 30

4

Junttila, 2022

vanilla beans

vanilla flavor

ethanol;
ethyl acetate; pentane; acetonitrile

room temperature; 50; 100

3; 10; 20

1; 3

Cicchetti and Chaintreau, 2009

alfalfa and citrus leaves

pesticides

ethyl acetate/
n-hexane

80

10

3

Kinross et al., 2020

 

Further information:

  • Arapitsas, P., and Turner, C. (2008). Pressurized solvent extraction and monolithic column-HPLC/DAD analysis of anthocyanins in red cabbage. Talanta 74, 1218–1223. doi: 10.1016/j.talanta.2007.08.029.
  • Barros, F., Dykes, L., Awika, J. M., and Rooney, L. W. (2013). Accelerated solvent extraction of phenolic compounds from sorghum brans. Journal of Cereal Science 58, 305–312. doi: 10.1016/j.jcs.2013.05.011.
  • Cicchetti, E., and Chaintreau, A. (2009). Comparison of extraction techniques and modeling of accelerated solvent extraction for the authentication of natural vanilla flavors. J of Separation Science 32, 1957–1964. doi: 10.1002/jssc.200800650.
  • Junttila, M. H. (2022). Extraction of brewers’ spent grain in near subcritical conditions: A method to obtain high protein contents extracts. Journal of Agriculture and Food Research 10, 100378. doi: 10.1016/j.jafr.2022.100378.
  • Kettle, A. (n.d.). Thermo Scientific Application Note 325: Extraction of Oil Content from Oilseeds by Accelerated Solvent Extraction.
  • Kinross, A. D., Hageman, K. J., Doucette, W. J., and Foster, A. L. (2020). Comparison of Accelerated Solvent Extraction (ASE) and Energized Dispersive Guided Extraction (EDGE) for the analysis of pesticides in leaves. Journal of Chromatography A 1627, 461414. doi: 10.1016/j.chroma.2020.461414.
  • Li, J., Zhang, S., Zhang, M., and Sun, B. (2019). Novel approach for extraction of grape skin antioxidants by accelerated solvent extraction: Box–Behnken design optimization. J Food Sci Technol 56, 4879–4890. doi: 10.1007/s13197-019-03958-5.
  • Repajić, M., Cegledi, E., Kruk, V., Pedisić, S., Çınar, F., Bursać Kovačević, D., et al. (2020). Accelerated Solvent Extraction as a Green Tool for the Recovery of Polyphenols and Pigments from Wild Nettle Leaves. Processes 8, 803. doi: 10.3390/pr8070803.
  • Šeregelj, V., Tumbas-Šaponjac, V., Mandic, A., Cetkovic, G., Čanadanovic-Brunet, J., Vulic, J., et al. (2018). Accelerated solvent extraction of bioactive compounds from carrot: Optimization of response surface methodology. J Serb Chem Soc 83, 1223–1228. doi: 10.2298/JSC180531068S.



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