Laboratory filtration: how can a sample be clarified or sterilised effectively?

From straightforward clarification to the sterility levels demanded by pharma, filtration is the step that safeguards your analyses and your instruments. Prepare ultra-clean HPLC solvents, sterilise your culture media, clarify lysates and complex samples, and safely vent bottles and bioreactors. Filters syringe, membranes, vacuum filtration units, Büchner funnels, filter capsules, vent filters, holders and vacuum flasks: Dutscher covers every need, from microlitre to litre, with fit-for-purpose materials and validated performance.

Which filtration systems and consumables are available?

From filter paper to high-performance membranes, every solution is built for a defined task.
• Filter paper: different retentions and flow rates (slow, medium, fast), ashless grades for gravimetric analysis. Team with a Büchner funnel and a vacuum flask to boost throughput.
• Filtration membranes (25/47/90 mm discs): select material by chemistry and sample. Hydrophobic PTFE for solvents and gases, low-extractable PES for media, versatile Nylon, PVDF/CA for low protein binding. Typical pore sizes: 0.22 µm (sterilising grade), 0.45 µm (clarification).
• Syringe filters: sterile or non-sterile, Luer-Lock fittings, 4–33 mm diameters. Essential for HPLC (protecting columns and needles) and fast sample prep.
• Syringeless filters for HPLC: 47 mm membranes on a filter holder or bottle-top units to prepare medium to large volumes with a receiver bottle.
• Filtration units (bottle-top or vacuum assemblies): sterile, ready to use, 45 mm necks, 0.22/0.45 µm membranes for media and buffers.
• Filter capsules and prefilters: for high flow rates or heavily loaded matrices (upstream glass fibre to prevent clogging).
• Air filtration / vent filters: hydrophobic PTFE 0.2 µm membranes for sterile venting of bottles, fermenters and carboys.
• 96-well filtration plates: clarification, SPE, high-throughput DNA/RNA.
Selection criteria: fluid type (aqueous/organic), chemical compatibility, volume and available pressure/vacuum, particle load, need for sterility, low extractables, connections and traceability.

Membrane type	Principle	Applications
PTFE (hydrophobic)	Repels water, highly solvent-resistant	Gases, venting, solvents and HPLC phases
PES (hydrophilic)	Low extractables, high flow	Media, buffers, 0.22 µm sterilisation
Nylon	All-rounder, good resistance	Aqueous and mild organics, routine QC
PVDF / CA	Low protein binding	Biomolecules, enzymes, sensitive samples

Which sectors and applications use filtration solutions?

• Life sciences / cell culture : sterilisation of media and buffers, sterile aeration via vent filters, clarification of lysates.
• Pharmaceutical : 0.22 µm sterilising filtration, process validation, low extractables, batch traceability.
• Chemistry / HPLC : preparation of solvents and samples, pump/column protection, syringe filters and PTFE membranes.
• Food & beverage : microbiological control by membrane filtration, physico-chemical analyses (turbidity, suspended solids).
• Environment : water filtration, particle sampling, microplastics, metals (ashless paper).
• Cosmetics : clarification and microbiological safety of actives, fragrances and bases.
From microlitre to litre, under pressure or vacuum, each configuration optimises flow rate, yield and reproducibility.

Available filtration solutions

Frequently asked questions about laboratory filtration

How do I choose between 0.22 µm and 0.45 µm for my aqueous samples, solvents and HPLC preps without sacrificing flow or compromising sterility or clarity?
0.22 µm retains bacteria and sterilises solutions. 0.45 µm clears heavily loaded matrices faster. In HPLC, 0.22 µm best protects columns/needles when the particulate load is fine.

Which membrane should I pick (PTFE, PES, Nylon, PVDF/CA) considering chemical compatibility, protein binding, extractables and use in cell culture, pharma or solvent analysis?
PTFE for solvents/gases; PES hydrophilic, low extractables; Nylon all-rounder; PVDF/CA for low protein binding. Check compatibility charts and sterility needs.

When should I use a glass fibre prefilter or a filter capsule instead of a simple syringe filter to avoid clogging and loss of flow on difficult matrices?
For particle-rich/viscous samples, add a prefilter (GF) or move to a high-capacity capsule. You’ll increase dirt-holding capacity and keep stable flow rates.

Vacuum filtration with a Büchner funnel and vacuum flask: what safety points (glassware, pressure, solvents) and best practices ensure optimal flow with no leaks?
Inspect the glassware, use a non-return valve/trap and a safety shield, match the vacuum pump, keep seals and joints clean and dry, and seat the paper properly. Avoid solvents incompatible with gaskets and membranes.

Are bottle-top filtration units suitable for sterilising culture media and buffers, and up to what volumes and temperatures can they be used routinely?
Yes—sterile at 0.22 µm, often up to 1–2 L. Use suitable receiver bottles (GL 45 neck), avoid hot solutions; some units tolerate 50–60 °C—check the manufacturer’s instructions.

How can I minimise extractables and blanks in HPLC/LC-MS when preparing solvents and filtered samples before analytical injection?
Choose membranes with low extractables (PES, PTFE), pre-rinse if needed, use clean housings, avoid additives, and work with LC-certified consumables.

Can filter holders be reused, and which components are strictly single-use to maintain compliance and microbiological safety?
Holders in glass/stainless steel are reusable after cleaning and autoclaving. Membranes, syringe filters and sterile units are single-use to preserve performance and sterility.