Autofil® PP bottle-top filters for solvent filtration are a revolutionary new way to purify solvents for analytical applications to obtain sterilized or purified extracts.
The primary function of solvent-compatible bottle-top filters in the general lab space is pre-filtration of solvents used in HPLC (High Performance Liquid Chromatography). HPLC is an analytical technique used to separate, quantify, and identify the components of a mixture. HPLC is used in countless industries, but is most notable in pharmaceutical, biochemical, biological, medical, and research areas. Common uses include drug testing, medical testing, drug purity testing in production, analysis of components of biological or chemical samples.
All HPLC processing relies upon a “mobile phase” composed of solvent—this mobile phase is mixed with the sample being analyzed, and used to deliver it through the HPLC machine, allowing it to be separated into parts and analyzed. This solvent, or mobile phase, must be completely free of contaminants or particulates. Particulate matter can damage the inner workings of HPLC machines, requiring very costly repairs, and potentially throwing off analytical accuracy. Biological contaminants in the mobile phase lead to risk of growth inside the solvent intake lines, which can lead to similar (again, costly) issues.
To avoid these harmful situations, many labs will pre-filter their HPLC solvents. This generally involves the use of side-arm Erlenmeyer vacuum flasks, rubber stoppers, glass Buchner funnels, die-cut membranes, and other expensive, breakable, movable parts. Any glassware will require cleaning, and risks shattering. The filtration requires supervision due to the risk of tipping over, and also requires pouring the solvent into another vessel as a final step, since the Erlenmeyer flask is hardly a good storage vessel for volatile solvents. The alternative to this pre-filtration is to buy HPLC-grade solvents, which can be expensive.
Another use for the Autofil® PP bottle-top filters is Cannabis extraction. Cannabis extraction is a process that utilizes a solvent to extract THC, CBD, and other cannabinoids, as well as terpenes, from cannabis plant matter. THC is the primary psychoactive ingredient in marijuana, while CBD provides various health effects, and terpenes provide flavor and other health benefits. The three major solvent types used in cannabinoid extraction are CO2, hydrocarbon (butane or propane), and ethanol.
Ethanol is the cheapest and simplest extraction method, but requires more “cleanup” of the extract to achieve a pure product. Hydrocarbons are often faster, and produce a purer product, but require more expensive equipment. They also present issues of risk related to the use of flammable solvent, and of incomplete removal of these harmful solvents from the final product. CO2 is generally the most expensive and highest-quality process, yielding a product that is guaranteed free of solvent. CO2 extraction requires very high-cost assemblies, and is generally only used in higher-end labs.
In all three extraction methods, the initial extraction step produces a crude product, generally contaminated with waxes, oils, lipids, and pigments. Each solvent leads to varying incidences of these impurities—ethanol yields more pigments, hydrocarbons yield mostly waxes, etc. All three methods require a step referred to as winterization. In the case of non-ethanol extractions, the product will usually be re-dissolved in ethanol, so ethanol is the standard here. In short, winterization involves chilling the sample to sub-zero temperature, waiting for oils and lipids to precipitate out of solution, and then quickly filtering the ethanol to strain out these oils and lipids. From here, the sample is either stripped of solvent via rotary evaporation (creating a final product), or put through the process of pigment removal.
Pigment removal is intended mostly for ethanol extractions, but may apply to others. Pigments like chlorophyll lower purity of product and alter color. For these reasons, they are often removed by the addition of activated carbon. The carbon absorbs the pigments, and can then be filtered out of the mixture, yielding a purer extract to be treated by rotary evaporation as above. Again, this step requires filtration.
In either case, filtration is generally very crude. End users often use simple setups with coffee filters and the like—more refined setups use side-arm Erlenmeyer flasks and Buchner Funnels. These filtration's involve costly parts, require supervision, run slowly and inefficiently, risk breakage of glassware, and are prone to incomplete or ineffective filtration.
Autofill PP filters come in three membrane types.
PES: Exhibits very low protein binding and extractables. Faster than Cellulose Acetate and Nylon membrane.
Nylon: Naturally hydrophilic and has greater chemical compatibility than other membranes. Extremely low extractables. Best used with solutions containing little or no protein.
PTFE: Naturally hydrophobic. Great chemical compatibility, making it exceptional for filtering aggressive solvents.
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