At Ousia Labs we leverage our patented low-temperature, moderate‐pressure extraction system operating at approximately 30 °F to 80 °F (~ −1 °C to 27 °C) and below 800 psi (~55 bar) to perform botanical extractions and prep-chromatography. In this blog post we’ll explore how these conditions, combined with selected co-solvents (e.g., pentane, butane, ethanol, ethyl acetate), deliver exceptional extraction efficiency, high selectivity, and minimal solvent usage—and how the underlying science supports these advantages.
Why Subcritical Fluid – CO2? The baseline solvent advantages
Here are key reasons CO₂ is an excellent extraction medium, particularly when paired with co-solvents:
- Inert, non-toxic, non-flammable (Green Solvent): Here’s a strong article supporting the use of Carbon dioxide (CO₂) as a “green solvent”: Green Extraction of Plant Materials Using Supercritical CO₂ (Yıldırım M., 2024) — This review notes that: “The supercritical CO₂ extraction method has gained attention due to its use of environmentally friendly, non-toxic solvents, ability to operate at lower temperatures … and reduce the use of organic solvents … thereby minimizing environmental issues.” MDPI
- Tunability: The density (and thus solvating power) of CO₂ can be varied by adjusting temperature and pressure, allowing tuning of extraction selectivity. “These properties (of SC-CO₂) can be widely adjusted by altering the operational conditions … enabling selective extraction, fractionation and purification of target compounds.” (BioMed Central). Another article about how supercritical fluid extraction is a tunable process for the selective extraction of fats and essential oil from coriander seeds (2015/16) — Indicates directly that the process is “tuneable” for selective extraction of different fractions from coriander seeds. (ResearchGate)
- Easy removal: After extraction, CO₂ simply depressurizes to gas and leaves little to no solvent residue. (PMC)
- Good for thermally sensitive compounds: Because CO₂ extraction can be done at moderate temperatures, it helps preserve labile compounds (e.g., terpenes, fragile phytochemicals). “The scCO₂ extraction stands out for its remarkable ability to preserve heat-sensitive bioactive compounds.” (jdc.jefferson.edu)
- Behavior vis-à-vis chirality: CO₂ as a solvent is symmetric and does not introduce chiral discrimination—thus it does not bias one enantiomer over another in extraction because the solvent is achiral. (Solvent chirality issues arise when using chiral solvents or additives; CO₂ avoids that.)
- Compatibility with co-solvents: CO₂ works well as a “base fluid” with small volumes of co‐solvents (ethanol, ethyl acetate, pentane, etc.) to enhance extraction of more polar compounds. For example: addition of ethanol as co-solvent improved SC-CO₂ yields in a 2021 study. (MDPI)
Given those baseline advantages, it’s clear why Ousia Labs selected CO₂ as the core solvent for our extraction and prep process.
Low-Temperature / Moderate-Pressure Operation: Why it matters.
Most supercritical fluid extraction (SFE) systems operate at elevated temperatures (e.g., 40-80 °C or higher) and pressures often in the hundreds of bars (>200 bar). By contrast, Ousia Labs’ systems operate at 30 °F-80 °F (≈ −1-27 °C) and below ~800 psi (~55 bar)—which is significantly lower pressure (and temperature) than many conventional SFX setups.
Here are several benefits of these milder conditions:
- Protection of thermally sensitive compounds: Lower temperatures reduce risk of decarboxylation, oxidation, or volatilization of delicate compounds (e.g., terpenes, flavonoids).
- Less thermal stress on the matrix: The biomass undergoes less thermal damage, preserving native chemical composition.
- Lower energy consumption: Running at lower pressure and temperature reduces compressor and heating/cooling load.
- Improved selectivity for targeted compounds: At lower pressures/densities, CO₂ may behave more like a gas-liquid hybrid solvent with certain selectivity benefits.
- Reduced matrix swelling and unwanted extraction: Higher pressure tends to force extraction of lipids, waxes, pigments; lower pressures can avoid some of those co-extracted impurities.
While many literature references consider higher pressures, there is good support in the literature for the concept that milder conditions (and appropriate co-solvent addition) still deliver efficient extraction.
For example, here are several studies demonstrating that ethanol as co‐solvent enhances extraction yield of moderately polar to semi‐polar compounds (phenolics, carotenoids, fatty acids) when used with CO₂:
1.) ResearchGate – They compared several modifiers including ethanol and found ethanol co‐solvent improved caffeine yield compared to pure SFE under the conditions tested (~30 MPa, 343 K).
2.) MDPI – Another review emphasizes that CO₂ is a “low-critical‐temperature solvent” as compared with conventional liquid solvents, making it desirable for thermally labile compounds.
3.) UNL Institutional Repository – Demonstrated that ethanol-modified SFE improved extraction of astaxanthin from a high-oil feedstock, used as a “green method”.
4.) ResearchGate – This study used CO₂‐expanded ethanol (i.e., ethanol rich phase with CO₂) to improve kinetics and require lower solvent volumes vs. standard SFE / solid–liquid extraction. They found initial extraction rates up to ~10x faster.
These studies align with Ousia’s approach of keeping temperatures low (30–80 °F) and pressures below ~800 psi.
Co-Solvent & Solvent Choices: Pentane, Butane, Ethanol, Ethyl Acetate
A core advantage in our process is the use of small amounts of co-solvent along with CO₂. Here’s why and how:
Why use a co-solvent?
- Pure CO₂—even supercritical—has relatively low polarity. That means strongly polar compounds (e.g., some flavonoids, glycosides) are not well extracted by CO₂ alone. A review states: “neat SFX… does not have sufficient solvent strength to extract polar compounds. For this reason, the addition of 1–15 vol% of the organic modifier … is often used.” (Wiley Online Library)
- Co-solvent addition increases the relative permittivity and solvating power of the CO₂ mixture and often enhances mass transfer and solute solubilization. (PSE Community)
Choice of specific co-solvents
- Ethanol: Widely used, food‐grade, GRAS, compatible with CO₂. For instance: the “Effects of Ethanol on the Supercritical Carbon Dioxide Extraction” study found that adding small amounts of ethanol improved cannabinoid yields. (MDPI)
- Ethyl acetate: Offers intermediate polarity; used in CO₂‐expanded liquid studies (CO₂ + ethyl acetate) for bioactive extractions. (RSC Publishing)
- Pentane / Butane: Very low polarity, good for non-polar/volatile compounds like terpenes, essential oils. Here is a study that supports how these solvents are beneficial for extracting non-polar hydrophobic hydrocarbons substances. (MDPI)
- Butane: Although flammable and less ideal in some regulatory contexts, butane has been used for neutral terpene extraction because it doesn’t extract chlorophyll (a benefit) but may co-extract waxes. (Frontiers)
Small solvent volumes & extraction efficiency
One of the strong selling points of the Ousia process is that only a small volume of co-solvent is required relative to traditional liquid‐solvent extraction methods. The science supports this:
- In the “Carbon Dioxide Expanded Ethanol Extraction” (CXE) study, the authors found that the initial extraction rate was up to ten times faster than conventional SFE when using CO₂‐expanded ethanol (i.e., CO₂ + ethanol), and solvent volume required was substantially reduced. (ResearchGate)
- Another review states that by using compressed CO₂ along with a small amount of modifier, solvent consumption can be minimized compared to classical maceration or Soxhlet methods. (RSC Publishing)
Because Ousia’s system is optimized for low temperature, moderate pressure, and small co-solvent volumes, it means fewer purification steps (e.g., winterization, chlorophyll removal) and reduced solvent waste.
How Ousia’s System Leverages These Advantages
At Ousia Labs we have engineered our patented CO₂ extraction systems around key features:
- Low‐temperature window (30 °F to 80 °F)
- Ensures thermally labile biomolecules (e.g., terpenes, heat-sensitive compounds) are preserved.
- Reduces decarboxylation or isomerization that can occur at higher temperatures.
- Contributes to finer control of selectivity (less extraction of unwanted lipids).
- Moderate pressure (< 800 psi / ~55 bar)
- This pressure is significantly lower than many conventional supercritical systems (which may run 200–400 bar).
- The lower density of the CO₂ solvent under these conditions gives more “gas-like” diffusivity with “liquid‐like” solvating ability in the presence of co-solvent, improving penetration and reducing matrix resistance.
- Avoids unnecessarily high operational costs and equipment stress.
- Co-solvent usage (very small volumes) with pentane, butane, ethanol, ethyl acetate
- For example, if targeting non-polar volatile compounds (terpenes), pentane or butane may be used in minimal amounts to boost solubility while preserving volatile profiles.
- For slightly more polar targets (flavonoids, phenolics), ethanol or ethyl acetate as co-solvent with CO₂ provides enhanced solvating power and selectivity.
- Because the system is optimized, the co-solvent volume is significantly less than in conventional extraction, reducing solvent recovery burden and post-processing.
- High selectivity & minimal purification
- Because of the low temperature and moderate pressure, the extraction tends to yield cleaner extracts (less waxes, pigments, unwanted lipids) than high-pressure/high-temperature methods.
- Fewer downstream steps mean faster time to final product, lower cost, higher quality and fewer solvent residues.
- Scalable, lab-grade / prep-chromatography capability
- The system is designed for lab and small-scale prep work—extraction of botanical feedstocks, isolation of target compounds, and modular collaborations. Furthermore, they can easily be sized up and assembled in conjunction with one another to increase throughput and meet the demand.
- The flexibility in temperature/pressure/co-solvent makes it ideal for tailoring extractions rather than purely bulk commodity extraction.
- Ousia Lab’s systems are the most efficient and cost effective way to remove pesticides from your ingredients. Here is a link to a good article for A Beginners Guide to Preparative Chromatography https://www.waters.com/nextgen/us/en/education/primers/beginners-guide-to-preparative-sfc.html
Why Ousia’s Specs Matter (30 °F-80 °F, <800 psi)
Given the literature above, Ousia’s system specifications stand out in the following ways:
- Lower than typical SFX conditions: Many SFX processes run at >200 bar (≈2900 psi) and >40-60 °C; by contrast <800 psi (~55 bar) and ≤80 °F are gentle conditions.
- Reduced co-extraction of impurities: Lower pressures reduce solvent density and solvating power for unwanted components (waxes, lipids), enhancing selectivity for target molecules.
- Preservation of volatile/thermally sensitive compounds: The lower temperature means less degradation of terpenes, flavonoids, delicate biomolecules—a major advantage for botanical extracts and prep‐chromatography.
- Flexibility for co-solvent tuning: At these milder conditions, the system is ideally suited to add small volumes of co-solvent (pentane, butane, ethanol, ethyl acetate) to precisely tune solvent polarity and selectivity—allowing fewer solvents, less waste, and less purification downstream.
- Lower solvent (co-solvent) volume requirement: The literature supports that CO₂-based extraction with co-solvent uses significantly smaller amounts of organic solvent compared to classical liquid extractions (maceration, Soxhlet). This aligns with Ousia’s goal of minimal solvent usage and high efficiency.
- Operational cost savings & scalability: Lower pressure equipment demands less robust mechanical design, lower energy consumption, and potentially fewer safety/regulatory burdens compared to ultra–high‐pressure (>200 bar) systems.
- Ideal for lab‐grade, prep‐chromatography workflows: Rather than bulk commodity extraction, the Ousia system is well adapted for custom extraction/isolations, small runs, and high‐value targets. The flexibility and mild conditions support that niche.
Practical Considerations & Tips for Implementation
If you are considering using a low-temperature CO₂‐co-solvent system like ours for botanical extraction or small‐scale purification, here are tips drawn from the literature and our experience:
- Feedstock preparation matters: Smaller particle size, removal of large fibrous matter, consistent moisture content improve mass transfer. Some studies (for example the pentane vs ethanol terpenoid work) show that freezing the biomass (liquid nitrogen dip) improved results. (Joseph A DiVerdi)
- Optimize co-solvent volume and type: Use as little co-solvent as needed to boost solvating power. Excessive co-solvent may extract unwanted impurities. Studies show even small percentages (1-15 vol%) of ethanol in CO₂ are effective. (Wiley Online Library)
- Tune pressure/temperature for selectivity: If your target is highly non-polar (e.g., terpenes), operate at lower pressures/temperatures; if slightly more polar (flavonoids, phenolics), increase co‐solvent polarity and/or slightly increase pressure/temperature (while still staying within mild conditions). The literature on CO₂‐expanded liquids supports tuning. (RSC Publishing)
- Monitor solvent-to-biomass ratio: Many traditional liquid extractions require large solvent volume relative to biomass. With CO₂ + co‐solvent systems you can reduce solvent ratio, but you need to monitor whether yield is acceptable. Some studies show sample: solvent ratios like 1:15 were used for ethanol cold extraction. (PMC)
- Consider downstream purification minimalization: One of the benefits of mild CO₂/co‐solvent extraction is fewer downstream steps (winterization, chlorophyll removal). If extraction yields a cleaner crude, you save cost and time.
- Ensure solvent recovery and safety protocols: Even though co‐solvents are small in volume, you still must handle flammables (pentane, butane) or organics (ethyl acetate) with proper safety. CO₂ equipment must still be pressure rated and have proper venting, separation, and recovery systems.
- Phase behavior and system design matter: Mixed CO₂ + liquid solvents (e.g., CO₂-expanded liquids) sometimes produce multi-phase systems (liquid + gas + vapor) depending on mole fractions, temperature, pressure. It is critical to verify single‐phase solvent behavior to ensure consistent extraction. As one study states: “It is important that the obtained mixtures are homogeneous and occurring as single-phase liquids.” (RSC Publishing)
Limitations & How Ousia Addresses Them
No technology is without caveats. Some limitations of low-temperature CO₂ + co‐solvent systems include:
- Solubility of highly polar compounds: Pure CO₂ is weak for very polar solutes. That’s why co-solvent addition is required. Even then, extraction of very polar glycosides may still require specialized solvent systems. But Ousia’s system allows co‐solvent tuning (ethanol, ethyl acetate) to handle many moderate polar targets.
- Equipment design for non-supercritical region: At lower pressures and temperatures, CO₂ may not be strictly “supercritical” (depending on the exact conditions). But that doesn’t detract from efficacy; the process is closer to compressed‐liquid or dense‐gas extraction rather than full supercritical. Ousia’s patent and design accommodate this.
- Scale limitations: Many CO₂ extraction systems work best at large scale (tons) to amortize equipment cost. Ousia is optimized for lab/bench/medium scale, which is ideal for high‐value botanical extractions but might be less cost‐effective for commodity bulk.
- Need for process optimization: Because we deviate from “standard” high-pressure SFX methods, we emphasize method development (co-solvent %, temperature/pressure, flow rates, biomass prep) to get best yields per application.
- Regulatory/solvent residue concerns: While CO₂ leaves essentially Zero residue, co-solvent may. Ousia’s approach uses minimal volumes of co‐solvent, and the process includes solvent‐evaporation/recovery steps to ensure compliance.
However, given our system design and workflow, these limitations are well managed, and the benefits outweigh them for our target applications.
More Supporting Data & Literature Summary
Here are some key citations and take-away data points which support the approach:
- Effect of cosolvents (ethyl lactate, ethyl acetate and ethanol) on the supercritical CO₂ extraction of caffeine from green tea (Villanueva Bermejo et al. 2015)
- In this study the authors used CO₂ + various green co-solvents (ethyl lactate, ethyl acetate, ethanol) to extract caffeine from green tea leaves (a non-cannabinoid matrix). (ResearchGate)
- Key findings: Ethyl lactate gave the highest caffeine yield (~14.2 mg/g) in dynamic extraction, followed by ethanol (~10.8 mg/g) under identical conditions. Ethyl acetate was lower (~7 mg/g). This shows that adding a co-solvent improved extraction of a moderately polar compound (caffeine) compared to CO₂ alone. (ResearchGate)
- Al-Hamimi et al., “Carbon Dioxide Expanded Ethanol Extraction: Solubility and Extraction Kinetics of α-Pinene and cis-Verbenol” (2016) showed that CXE (CO₂-expanded ethanol) yields initial extraction rates up to ten times faster than classical SLE and lower solvent volume needed. (ResearchGate)
- Pilařová et al., “From supercritical carbon dioxide to gas expanded liquids” (2019) looked at CO₂/ethanol/water and CO₂/ethyl lactate/water mixtures across pressures 200–300 bar and temperatures 40-80 °C, showing that adding CO₂ to organic solvents (i.e., gas-expanded liquids) provides enhanced extraction and reduced solvent volume. (RSC Publishing)
Summary & Value Proposition for Ousia Labs’ Clients
In summary:
- Ousia Labs’ patented CO₂ extraction system operating at 30 °F-80 °F and <800 psi offers a mild, high‐selectivity extraction platform.
- Combined with small volumes of co-solvent (e.g., pentane, butane, ethanol, ethyl acetate), the system enables efficient extraction and isolation of target botanical compounds, with minimized solvent use, minimal thermal damage, and reduced purification burden.
- The scientific literature supports key points:
- CO₂ is a highly favorable solvent medium (green, tunable, easily removed).
- Co-solvent addition enhances solvating power and selectivity, enabling smaller solvent volumes.
- Moderate pressures/temperatures preserve thermally sensitive compounds and reduce unwanted extraction of lipids/waxes.
- For clients—whether universities doing research, companies isolating high‐value compounds, or formulations requiring high purity—this means:
- Cleaner extracts, fewer downstream steps.
- Lower solvent and energy cost per extraction.
- Flexibility to tune for different botanicals, target compounds, solvent systems.
- Compatibility with analytical and preparative chromatography given the low‐temperature, low‐stress conditions.
Let us work for you:
If you are working with botanical biomass and want to isolate or enrich specific compounds (terpenes, flavonoids, polyphenolics, cannabinoids, other actives) and you want a system that provides high purity, low solvent usage, and gentle processing, let’s talk. Ousia Labs offers not just the equipment, but the process development expertise (in engagement with our engineering team, field application team and analytical lab partners) to optimize your extraction.
We believe that our system represents a next‐generation approach to co-solvent CO₂ extraction—especially suited for labs, pilot runs and high‐value botanical extraction where quality, selectivity and solvent minimalization matter.
Order now and get started extracting and purifying your ingredients – CLICK HERE!