Whatman Filter Sizes: Performance, Specifications, and How to Apply It in Industry

Types of Whatman Filter Sizes and Accessories

Whatman filters are trusted in laboratories worldwide for their precision, consistency, and reliability in filtration applications ranging from sample preparation to analytical testing. Available in various sizes, pore ratings, and specialized configurations, Whatman products cater to diverse scientific needs including chromatography, microbiology, and environmental analysis.

This guide explores the most commonly used Whatman filter sizes and accessories, highlighting their features, applications, and ideal use cases to help you select the right product for your lab workflow.

Whatman 542 (5 µm)

A 5-micron glass fiber filter designed to act as a pre-filter for fine filtration processes. It effectively removes large particulates while maintaining high flow rates.

Advantages

• Excellent particle retention for coarse filtration
• High dirt-loading capacity
• Ideal for sample clarification
• Chemically resistant and ash-free options available

Limitations

• Not suitable for sterile filtration
• Larger pore size limits microbial removal

Best for: Pre-filtration, environmental testing, water quality analysis

Whatman CP Chromatography Filters

Specially engineered for chromatographic applications, these filters ensure bubble-free sample delivery and precise flow control. Designed with integrated clamps for secure fitment in tight setups.

Advantages

• Prevents bubble formation during sample injection
• Ensures consistent flow for accurate chromatography results
• Compatible with HPLC and GC sample preparation
• Minimizes contamination risk

Limitations

• Requires proper installation to avoid leaks
• Specialized use limits general applicability

Best for: HPLC sample prep, gas chromatography, sensitive analytical workflows

Whatman 25 mm Filters

A compact filtration solution widely used in small-volume applications. Its 25 mm diameter ensures compatibility with many standard syringe filter holders and autosamplers.

Advantages

• Perfect for low-volume samples
• Widely compatible with lab equipment
• Cost-effective for routine testing
• Available in multiple membrane types (PES, PVDF, nylon)

Limitations

• Limited surface area for high-load samples
• May clog quickly with turbid solutions

Best for: Small-scale research, analytical chemistry, syringe filtration

Whatman 47 mm Filters

A versatile and widely adopted size offering a balance between surface area and device compatibility. Commonly used in vacuum filtration and environmental monitoring.

Advantages

• Optimal surface-to-volume ratio
• Standard size for many filtration units
• Suitable for moderate to high-volume samples
• Used in microbial testing and particulate analysis

Limitations

• Larger than needed for micro-applications
• Slightly higher cost per unit than smaller sizes

Best for: Water testing, air sampling, microbiology, gravimetric analysis

Whatman 90 mm Filters

Designed for high-capacity filtration, the 90 mm size provides a large surface area, reducing clogging and extending filter life during prolonged use.

Advantages

• Large filtration area minimizes pressure drop
• Ideal for filtering large sample volumes
• Reduces frequency of filter changes
• Commonly used in environmental and industrial labs

Limitations

• Requires larger filtration apparatus
• Higher material cost per filter
• Not ideal for space-constrained setups

Best for: Bulk filtration, environmental monitoring, industrial process control

Whatman 593 Filter Holder

A compact, three-piece filtration assembly consisting of a base, filter support, and screw cap. Designed specifically for small-scale laboratory filtration with ease of use and leak-proof performance.

Advantages

• Durable and reusable design
• Simple assembly and disassembly
• Leak-resistant threaded closure
• Ideal for gravity or low-pressure filtration

Limitations

• Not suitable for high-pressure applications
• Limited to compatible filter sizes

Best for: Small-scale lab filtration, qualitative analysis, educational labs

Product	Size / Pore	Primary Use	Filtration Type	Ideal For
Whatman 542	5 µm	Pre-filtration	Glass Fiber	Clarification, environmental samples
CP Chromatography Filter	Various	Chromatography	Syringe/Membrane	HPLC, GC sample prep
Whatman 25 mm	25 mm	Small-volume	Membrane	Micro-filtration, autosamplers
Whatman 47 mm	47 mm	General-purpose	Vacuum/Membrane	Microbiology, water testing
Whatman 90 mm	90 mm	Bulk filtration	Membrane/Glass Fiber	High-volume samples, industrial use
Whatman 593 Holder	N/A	Support device	Filter housing	Lab-scale filtration setups

Expert Tip: When selecting a filter size, consider both sample volume and equipment compatibility. For high-throughput labs, larger filters like the 90 mm can reduce downtime due to clogging, while 25 mm or 47 mm filters offer versatility across instruments.

What Makes Whatman Filters Stand Out?

Whatman filters are globally recognized for their precision, consistency, and reliability in laboratory and industrial applications. Trusted by scientists and engineers alike, these filters are engineered to deliver accurate and reproducible results across a wide range of scientific disciplines. Their performance stems from carefully controlled manufacturing processes and a deep understanding of filtration science. Below are the key features that set Whatman filters apart from standard filtration products.

Micron Rating Precision

The micron rating of a Whatman filter defines the smallest particle size it can effectively capture. This specification is critical in determining the filter’s suitability for specific applications, as it directly impacts the purity and clarity of the filtrate. Whatman filters are manufactured with tight tolerances, ensuring consistent micron ratings across batches.

Available in a broad range—from ultrafine 0.2-micron membranes for sterile filtration to coarse 100-micron filters for particulate removal—Whatman offers solutions for virtually every filtration need. For example, a 0.2 µm filter is commonly used in microbiology to remove bacteria, while a 45 µm filter might be used in environmental sample preparation to remove large debris before analysis.

Controlled Pore Size and Structure

Pore size is a fundamental property closely related to micron rating but refers more specifically to the physical dimensions and distribution of pores within the filter matrix. Whatman employs advanced techniques to produce filters with uniform pore structures, enhancing flow rates and retention efficiency.

Filters are categorized based on pore size: mesoporous (10–100 µm) filters are ideal for pre-filtration and removal of large particulates, while microporous (0.2–2 µm) variants are used in critical applications such as bacterial retention, virus filtration, and HPLC sample preparation. This precision ensures that only the desired components pass through, maintaining sample integrity.

Versatile Filter Materials

Whatman filters are available in a diverse array of materials, each selected for its chemical compatibility, mechanical strength, and application-specific performance. Whether filtering aggressive solvents, biological fluids, or air samples, there's a Whatman filter designed to handle the challenge.

Common materials include:

• Cellulose – Natural, biodegradable, and ideal for aqueous solutions and general lab use.
• Nylon – Offers excellent chemical resistance and high tensile strength; suitable for aggressive solvents and protein-rich samples.
• PTFE (Teflon™) – Highly inert and hydrophobic, perfect for corrosive chemicals and air/gas filtration.
• PVDF – Low protein binding, making it ideal for biological and pharmaceutical applications.

This wide material selection allows researchers to match the filter to their sample type, minimizing interference and maximizing recovery.

Broad Application Range

Whatman filters are engineered for use across multiple high-stakes industries where purity and accuracy are non-negotiable. Their reliability makes them a staple in laboratories worldwide.

Key applications include:

• Microbiology – Sterilizing media, isolating microorganisms, and performing membrane filtration tests for water quality.
• Environmental Analysis – Filtering air, water, and soil samples for pollutant detection, including particulate matter and microbial contaminants.
• Pharmaceuticals – Ensuring sterility in drug formulation, quality control testing, and bioburden monitoring.
• Research & Diagnostics – Supporting techniques like cell culture, PCR, and immunoassays where sample cleanliness is crucial.

Each filter is validated for performance, ensuring compliance with regulatory standards such as USP, EP, and ISO.

Feature	Range/Options	Typical Use Cases
Micron Rating	0.2 µm to 100 µm	Sterile filtration (0.2–0.45 µm), pre-filtration (10–100 µm)
Pore Size Type	Microporous, Mesoporous	Bacterial retention, particulate removal, air sampling
Common Materials	Cellulose, Nylon, PTFE, PVDF, Glass Fiber	Aqueous solutions, organic solvents, biological samples, air/gas
Industries Served	Life Sciences, Environmental, Pharma, Industrial	Lab research, quality control, environmental monitoring

Important: Always select a Whatman filter based on your specific sample matrix, chemical compatibility, and required retention efficiency. Using an inappropriate filter can lead to sample contamination, inaccurate results, or membrane failure. Consult the product datasheet for detailed specifications, including flow rates, pressure limits, and autoclaving compatibility.

What Are the Specifications of Whatman 516LS Series Filters?

The Whatman 516LS series filter is a high-performance glass fiber filtration solution designed for demanding laboratory and industrial applications. Engineered for durability, precision, and efficiency, these filters are ideal for applications requiring reliable particle retention and consistent flow rates. Below is a comprehensive overview of technical specifications, usage guidelines, and best practices to ensure optimal performance and safety.

Technical Specifications

The Whatman 516LS series is constructed from robust, heat-treated borosilicate glass fibers arranged in a structured matrix to deliver superior mechanical strength and filtration efficiency. This design enables the filter to perform effectively under high-stress conditions, making it suitable for challenging separation tasks.

• Filter Surface Area: 116 square inches (approximately 748 cm²), allowing for high throughput and reduced clogging
• Mesh Size: 325 microns, providing a stable support structure
• Retention Range: 10–15 microns — effectively captures fine particulates while maintaining flow efficiency
• Pressure Resistance: Withstands up to 2 bar (29 psi) during normal operation, ensuring durability in pressurized systems
• Material Composition: High-purity glass fibers with thermal stabilization for consistent pore structure

Key Advantage: Superior solids loading capacity compared to conventional mesh screens, reducing the frequency of filter changes.

Installation Guide

Proper installation is essential for maintaining filter integrity and achieving accurate results. Follow these steps to install the Whatman 516LS filter correctly:

1. Disassemble the filter holder by carefully removing the cap and base.
2. Place the 516LS filter securely onto the pre-filter support ring, ensuring full contact and no wrinkles or gaps.
3. Reattach the base and cap, tightening evenly to avoid warping the filter or creating leaks.
4. Inspect for proper seating and alignment before introducing fluid.

Pro Tip: Always handle the filter with clean gloves to prevent contamination and fiber damage.

Operating Instructions

To ensure safe and effective filtration, follow these usage guidelines when working with the Whatman 516LS series:

• Gently pass the liquid through the filter using a compatible filtration unit.
• Never exceed the maximum operating pressure of 3.5 bar (50.8 psi).
• Keep the operating temperature below 60°C (140°F) to prevent structural degradation.
• After each use, rinse the filter thoroughly with the same liquid used during filtration to remove residual particles.
• For aqueous solutions, deionized water can be used for final rinsing if needed.

Best Practice: Use gradual pressure increases to avoid sudden stress on the filter matrix.

Maintenance & Longevity

Regular maintenance extends the life of both the filter and the filtration system:

• Clean the filter holder components (cap, base, seals) after each use to prevent buildup and cross-contamination.
• Store the filter in a dry, dust-free environment when not in use.
• Never expose the filter to pressures above 3.5 bar or temperatures exceeding 60°C.
• Inspect the filter regularly for signs of wear, such as tears, discoloration, or reduced flow rate.
• Replace the filter immediately if damage is detected or performance declines.

Maintenance Tip: Label filters with usage dates to track lifespan and prevent overuse.

What Happens If You Exceed Maximum Operating Limits?

Operating the Whatman 516LS filter beyond its specified pressure or temperature limits can lead to irreversible damage and compromised results:

• Overpressure (above 3.5 bar): May cause cracking or rupture of the glass fiber matrix, leading to breakthrough of unfiltered particles.
• Excessive Heat (above 60°C): Can degrade the fiber structure, alter pore size, and reduce filtration efficiency.
• Combined Stress: Simultaneous overpressure and overheating significantly increase the risk of catastrophic failure.
• Sample Contamination: Damaged filters may release glass fragments or allow unfiltered contaminants into the sample, compromising data integrity.
• System Damage: Failure can lead to downstream contamination or damage to pumps and collection vessels.

Safety & Cost Warning: Repeatedly exceeding operational limits not only risks inaccurate results but also increases replacement costs and downtime. Always adhere to manufacturer specifications to ensure reliability, safety, and cost-effective operation.

Parameter	Value	Notes
Material	Borosilicate Glass Fiber	Heat-treated for enhanced durability
Surface Area	116 in² (748 cm²)	High capacity for extended use
Mesh Size	325 microns	Structural support layer
Retention Range	10–15 microns	Effective for fine particulate removal
Max Operating Pressure	3.5 bar (50.8 psi)	Absolute upper limit — do not exceed
Max Operating Temperature	60°C (140°F)	Avoid thermal shock and prolonged exposure
Recommended Storage	Dry, room temperature	Protect from moisture and dust

Expert Recommendation: For critical applications, consider using a pressure gauge and temperature sensor in-line to monitor operating conditions in real time. Pairing the 516LS filter with a protective pre-filter can further extend its service life and improve overall system efficiency.

How to Choose the Right Whatman Filter: A Comprehensive Guide

Selecting the appropriate Whatman filter is essential for achieving accurate, reliable results in laboratory applications ranging from biological research to environmental monitoring. With a wide variety of materials, pore sizes, and configurations available, understanding key selection criteria ensures optimal filtration performance, sample integrity, and equipment longevity. This guide breaks down the most critical factors to consider when choosing a Whatman filter for your specific application.

Important Note: Always verify chemical compatibility between your sample and the filter membrane. Exposure to incompatible solvents or extreme pH levels can compromise membrane integrity and lead to inaccurate results or system failure.

1. Sample Type: Matching Filter Chemistry to Your Application

The nature of your sample is the primary factor in determining the best filter material. Whatman offers specialized membranes designed to preserve sample integrity while efficiently removing contaminants.

• Biological Samples: For protein-rich solutions, nucleic acids, or cell cultures, nitrocellulose and nylon membranes are commonly used. Nitrocellulose provides excellent protein binding with minimal leachables, making it ideal for applications requiring high sample purity such as blotting or immunoassays. It delivers exceptionally clean filtrate with low background interference.
• Nylon Membranes: Known for high protein retention and durability, nylon filters are hydrophilic and exhibit strong affinity for proteins. While they may absorb more protein than nitrocellulose, surface-modified nylon variants reduce binding and are suitable for sensitive biological workflows where recovery is critical.
• Environmental & Industrial Samples: When dealing with aggressive solvents, acids, bases, or oily matrices, chemically resistant materials like PTFE (polytetrafluoroethylene) or cellulose acetate are recommended. PTFE is hydrophobic and inert, capable of withstanding harsh chemicals and high temperatures, making it perfect for solvent filtration and air monitoring. Cellulose acetate offers good chemical resistance with high flow rates and low protein binding, ideal for aqueous solutions and HPLC sample preparation.

2. Filter Pore Size: Balancing Efficiency and Flow Rate

Pore size, measured in microns (µm), determines the smallest particle the filter can retain. Selecting the correct size is crucial for effective separation without unnecessary clogging.

• Coarse Filtration (5 µm and above): Ideal for pre-filtration to remove large particulates and debris. These filters extend the life of downstream finer filters by reducing loading and preventing premature blockage.
• Microfiltration (0.1–5 µm): Used for removing bacteria, yeast, and fine particulates. A 0.22 µm pore size is standard for sterile filtration, ensuring removal of most microorganisms. A 0.45 µm filter is often used for general clarification where sterility is not required.
• Ultrafiltration Considerations: While Whatman primarily focuses on microfiltration, pairing appropriate pore sizes with material selection can achieve near-ultrafiltration performance for macromolecule retention in certain applications.

Choosing the right pore size improves filtration efficiency, reduces processing time, and enhances filter lifespan by minimizing fouling.

3. Membrane Material Properties and Compatibility

Each membrane material has distinct physical and chemical characteristics that influence its suitability for specific applications.

Membrane Material	Key Properties	Best For	Limited Use In
Nitrocellulose	High protein binding, low extractables, hydrophilic	Blotting, diagnostics, biological sample clarification	Strong organic solvents, high-pressure systems
Nylon	Durable, hydrophilic, moderate protein binding (reduced in modified versions)	General lab filtration, HPLC, aqueous solutions	Concentrated acids, DMSO, chlorinated solvents
PTFE	Chemically inert, hydrophobic, thermally stable	Solvent filtration, aggressive chemicals, venting	Aqueous solutions (unless surfactant-treated)
Cellulose Acetate	Low protein binding, high flow rate, biodegradable	HPLC, cell culture media, biological fluids	Acetone, chloroform, strong bases
Glass Microfiber	High dirt-loading capacity, binder-free options available	Particulate collection, air sampling, pre-filtration	High-pressure liquid systems

4. Precipitate and Particulate Filtration: Handling Challenging Samples

When filtering samples containing precipitates or high particulate loads, selecting a filter with high dirt-holding capacity is essential to prevent rapid clogging and ensure consistent flow.

• Glass Microfiber Filters: Exceptional for retaining sub-micron particles (down to 0.3 µm or less in some grades). They offer high thermal stability and are often used in gravimetric analysis, air monitoring, and pre-filtration. Their depth filtration mechanism traps particles throughout the matrix, not just on the surface.
• Cellulose Acetate Filters: Feature a tight, uniform mesh structure that effectively captures fine particulates while maintaining high flow rates. Ideal for producing clear filtrate in applications like beverage testing or environmental water analysis.
• Multi-Fiber Composite Filters: Combine different fiber types (e.g., cellulose and glass) to enhance loading capacity and mechanical strength. These are excellent for dirty or complex samples, providing longer service life and reduced downtime.

Proper selection prevents frequent filter changes, minimizes contamination risks, and ensures consistent filtration performance across batches.

Expert Tip: Always perform a small-scale test run when switching filter types or processing a new sample. This helps verify compatibility, flow rate, and retention efficiency before scaling up, saving time and resources in the long run.

Final Selection Checklist

• ✔ Confirm sample compatibility with the membrane material
• ✔ Select pore size based on target particle removal and sterility needs
• ✔ Consider flow rate requirements and system pressure limitations
• ✔ Evaluate particulate load and choose high-capacity filters if needed
• ✔ Check for certifications (e.g., sterile, DNAse/RNAse-free, pyrogen-free) if required
• ✔ Refer to Whatman’s compatibility charts and technical datasheets for validation

By carefully evaluating your sample type, required pore size, membrane chemistry, and particulate load, you can confidently select the optimal Whatman filter for your application. Proper filtration not only protects sensitive instruments like HPLC systems but also ensures the accuracy and reproducibility of your analytical results. When in doubt, consult manufacturer guidelines or technical support to confirm compatibility and performance expectations.

Frequently Asked Questions About Whatman Filters

Q1: Are Whatman filters sterile?

A1: Some Whatman filters are sterile, meaning they have undergone a validated sterilization process—typically gamma irradiation or autoclaving—to eliminate all microorganisms, including bacteria, viruses, and spores. These sterile filters are individually packaged and labeled, making them ideal for applications in microbiology, cell culture, pharmaceutical testing, and other sensitive laboratory procedures where contamination must be avoided.

On the other hand, non-sterile Whatman filters are designed for general filtration tasks such as sample preparation, particulate removal, or environmental testing, where sterility is not a critical requirement. Always check the product packaging or specification sheet to confirm whether a particular filter is supplied sterile.

Q2: How long do Whatman filters last?

A2: The lifespan of a Whatman filter depends on several factors, including the volume and nature of the sample, the viscosity of the liquid, the concentration of particulates, and the specific application. While the filter itself does not have an expiration date when stored properly, its functional life during use is limited by clogging and physical degradation.

• Sterile filters: Often used in biological applications involving microbial loads or protein-rich solutions, which can cause faster pore blockage. As a result, they may have a shorter effective filtration life compared to non-sterile counterparts used in less demanding applications.
• Non-sterile filters: Typically used for routine particulate filtration in industrial or environmental labs, where they may last longer due to lower biological loading.
• Storage longevity: Unused Whatman filters can remain effective for years if stored in a cool, dry place away from direct sunlight and contaminants. However, once opened or exposed to moisture, their performance may degrade over time.

It's important to replace the filter at the first sign of reduced flow rate, visible damage, or breakthrough contamination to maintain filtration integrity.

Q3: Are Whatman filters reusable?

A3: No, Whatman filters are designed for single-use only and are not recommended for reuse. They are precision-engineered disposable products intended to ensure consistent performance, reliability, and sterility across critical applications.

Although some users attempt to clean and reuse filters to reduce costs, doing so poses significant risks:

• Sterility compromise: Washing cannot reliably remove all microorganisms or pyrogens, especially from microporous structures, increasing the risk of cross-contamination.
• Structural damage: The delicate filter matrix may be damaged during cleaning, leading to tears, reduced pore integrity, or inconsistent flow rates.
• Performance decline: Reused filters often exhibit reduced efficiency, higher background noise, or particle shedding, which can affect experimental accuracy.
• Manufacturer stance: GE Healthcare (the manufacturer of Whatman products) explicitly advises against reuse and does not guarantee performance or sterility for any filter that has been cleaned or reprocessed.

For cost-effective and sustainable lab practices, consider selecting the appropriate pore size and diameter to maximize throughput and minimize waste, rather than attempting reuse.

Q4: What is the micron rating of Whatman filter paper?

A4: Whatman filter papers are available in a wide range of micron (μm) ratings, which indicate the size of particles the filter can retain. The micron rating defines the average pore size and determines the filtration efficiency for different types of contaminants.

Common Whatman filter paper grades and their typical micron ratings include:

Filter Grade	Typical Micron Rating	Common Applications
Grade 1	11 μm	General filtration, soil analysis, air monitoring
Grade 2	8 μm	Clarification of beverages, water testing
Grade 3	6 μm	Gravimetric analysis, particulate collection
Grade 4 (Rapid)	20–25 μm	Coarse filtration, settling slurry removal
Grade 5	2.5 μm	Differential filtration, fine particle retention
Grade 41	0.45 μm	Sterile filtration, HPLC sample prep
GF/A	1.6 μm	Cell collection, air pollution monitoring
GF/F	0.7 μm	Nutrient analysis, microbial assays

The choice of micron rating depends on your specific application—larger pores (e.g., 20 μm) allow faster flow for coarse filtration, while smaller pores (e.g., 0.22 μm or 0.45 μm) are used for sterile filtration or fine particulate removal. Always refer to the product datasheet for exact specifications and compatibility with solvents or biological samples.