Filtration is a fundamental process in laboratories across industries, from pharmaceutical development and botanical extraction to chemical manufacturing and environmental testing. The right filtration setup ensures purity, precision, and regulatory compliance.

However, not all filtration systems are created equal. If you're separating solids from liquids, clarifying extracts, or removing impurities on a molecular level, your chosen tools will directly affect your workflow efficiency and final results.

What Is Filtration?

In laboratories, filtration is a physical separation process where a porous medium (like filter paper or membranes) retains solid particles or suspended material while allowing liquids or gases to pass through. 

It’s used to: 

• Clarify solutions by removing particulates 
• Isolate solids, including crystalline precipitates or biological cells
• Sterilize fluids via size-exclusion (removing bacteria and microorganisms) using 0.2 μm membranes

Büchner Funnels and Filter Flasks

Büchner funnels are rigid, vacuum-compatible funnels that hold filter paper across a perforated plate. When connected to a filter flask and vacuum pump, they create suction that rapidly draws liquid through the paper while retaining solids.

Available in glass or porcelain for most solvent applications and plastic for single-use or corrosive samples, this method is significantly faster than gravity filtration and yields cleaner, drier solids. 

It’s ideal for isolating recrystallized products, harvesting botanical solids from ethanol/water extracts, and handling medium-to-large volume vacuum filtrations. Its speed and efficiency make it indispensable for crystallization and botanical extraction workflows.

Vacuum Pumps

Vacuum pumps are the driving force behind pressure-assisted filtration systems. They reduce atmospheric pressure in a closed vessel, pulling liquids through filter media more rapidly and efficiently than passive methods.

Common Lab Pump Types:

• Rotary Vane Pumps: High vacuum levels; used in drying, distillation, and filtration
• Diaphragm Pumps: Oil-free and chemically resistant; ideal for corrosive samples and sterile work
• Scroll Pumps: Quiet, long-lasting, low-maintenance; best for sensitive environments and long runs

Best for:

• Vacuum filtration (Büchner funnels, membrane filters)
• Degassing and solvent removal (HPLC prep, reaction mixtures)
• Supporting vacuum ovens, rotary evaporators, and freeze dryers

Match the pump type to your desired vacuum depth, solvent compatibility, and lab noise tolerance.

Membrane Filters

Membrane filters are thin films with uniform pore structures that block particulates based on size. They’re available in disc or cartridge formats to clarify, sterilize, or prepare samples before analysis.

Pore sizes:

• 0.45 μm: Removes general particulates 
• 0.2 μm: Sterile filtration (bacteria and fine particles)

Materials:

• PTFE: Chemical-resistant; for aggressive solvents 
• Nylon: General-purpose; good for aqueous and alcohol-based solutions 
• PES: Fast flow; low protein binding (ideal for biological samples) 
• Cellulose Acetate: Low extractables; used in microbiology and tissue culture

Best for: 

• Prepping HPLC/GC samples 
• Sterile filtration of reagents and buffers 
• Clarifying solvents or culture media

Always verify solvent compatibility with your membrane material.

Syringe Filters

Syringe filters are disposable, single-use filtration devices that attach to a syringe barrel. They allow quick filtration of small volumes (typically <100 mL) without setting up full-scale vacuum systems.

Each unit houses a membrane filter sealed in a plastic housing, and most are color-coded for material type and pore size.

Best for:

• Sample prep for HPLC/GC/MS analysis
• Removing particulates from solvents or reagents 
• Filtering proteins or DNA prep buffers

Advantages:

• No risk of cross-contamination 
• Compatible with sterile workflows 
• Quick and low waste for <100 mL samples

Match the membrane material and the housing plastic to your sample’s chemistry. For instance, PES membranes work well with protein-rich solutions, and polypropylene housings are compatible with most solvents.

Filter Paper

Filter paper provides the physical barrier in both gravity and vacuum filtration setups. Available in varying retention levels and flow rates, it's chosen based on the particle size to be removed and the type of funnel used.

Types:

• Qualitative Paper: For general separation (not suitable for quantitative residue analysis) 
• Quantitative (Ashless) Paper: Leaves minimal ash after ignition; used for precise gravimetric work
• Glass Fiber Filters: High loading capacity and excellent chemical resistance; ideal for viscous or aggressive solutions

Best for:

• General lab separations
• Gravimetric analysis
• Filtering crystallization solids

Always select the correct diameter for your funnel and verify chemical compatibility with your sample or solvent.

Adsorbents

Adsorbents are solid materials that capture unwanted compounds from a solution through surface interaction rather than absorption. They're essential for purification and remediation, especially when clarity, color, or chemical composition matters.

Used for: Removing pigments, waxes, fats, residual solvents, pesticides, polar compounds, and odors.

Common types include:

• Activated Carbon: General-purpose deodorization and decolorization 
• T-5 Clay (bentonite-based): Removes waxes, lipids, and dark pigments 
• Silica Gel: Targets polar contaminants and residual solvents; often used in chromatography 
• Alumina (acidic, neutral, basic): Separates acidic or basic compounds depending on grade 
• MagSil PR (Magnesium Silicate): Popular in cannabis CRC columns for pesticide and heavy metal remediation 
• Celite (Diatomaceous Earth): Used as a filtration aid to prevent clogging and improve flow 
• Activated Alumina: High surface area makes it effective for drying and removing fluoride, arsenic, or sulfur compounds 
• Zeolite: Effective for gas purification and moisture capture

These media are often packed into stainless steel CRC housings or used in-line with filtration columns during processing.

Separatory Funnels

Separatory funnels enable liquid-liquid extraction, where two immiscible solvents are separated based on density. They’re simple but essential tools in organic chemistry and plant extraction workflows.

Two liquids of different densities are added to the funnel. After settling, the denser layer can be drained from the bottom. Most lab-grade funnels are borosilicate glass, featuring PTFE stopcocks for chemical resistance and precise flow control.

Used for:

• Washing organic extracts with water or brine
• Removing aqueous contaminants from nonpolar solvents
• Separating hexane, ethanol, or other solvents from water layers

Centrifugal Filters

Centrifugal filters combine size-exclusion membranes with centrifugal force to separate, concentrate, or clean up macromolecules in solution. As the sample spins, smaller molecules pass through the membrane while larger ones are retained.

Used in:

• Concentrating proteins, DNA, or RNA 
• Removing cell debris after lysis
• Buffer exchange and desalting workflows

Consider:

• Molecular weight cut-off (MWCO): Choose based on the size of the molecules you want to retain
• Sample volume: Ensure the device capacity matches your input volume
• Centrifuge compatibility: Verify speed limits (RCF), rotor type, and tube size

Choosing the Right Filtration Setup

There’s no one-size-fits-all setup. The right filtration equipment depends on your application, materials, and processing scale:

• Volume: Are you filtering microliter-scale samples for analysis or liters of extract for processing?
• Target: Are you removing solids, sterilizing solutions, or purifying compounds like pigments, pesticides, or proteins?
• Compatibility: Will your filter media need to handle corrosive solvents, biomaterials, or resin-rich plant extracts?
• Speed: Is passive gravity filtration enough, or do you need vacuum-driven throughput for higher efficiency?
• Workflow style: Are you operating batch by batch, or integrating filtration into a continuous inline system?

Not sure where to start? USA Lab can help configure the proper setup based on your process, materials, and production goals.

Your Source for Reliable Filtration Equipment

At USA Lab, we offer a wide selection of filtration tools and supplies, from vacuum systems and Büchner funnels to high-grade adsorbents and membrane filters. 

Running a small lab or managing high-throughput extraction? We have the right filtration tools for your exact needs.

Browse our filtration products or contact our team for help finding the best setup for your workflow.