Lab Filters: what Claude and GPT would buy

Two AI models chose on their own, with no web access. Nobody tested these products: this is what each one says, and how to check it.

They disagree: Claude chooses Whatman and GPT chooses Millipore

In Industrial & Scientific, Claude and GPT choose the same brand in 52 of 107 categories.

Claude Opus 5.5 · October 28, 2026

Whatman (brand)

Whatman (Cytiva) covers papers, glass fiber, membranes and syringe filters, and its grade numbers are the shared reference most lab methods are written against.

Not for: Labs whose validated methods already name another supplier's catalog numbers, since switching brands can mean revalidating the method.

GPT 6.1 Sol · November 10, 2026

Millipore Millex-GP SLGP033RS

Sterile 0.22 µm PES syringe filter with low protein binding, well suited to routine filtration of aqueous laboratory solutions.

Not for: Organic solvents or high-volume filtration.

Check before you buy

Format matches the job. Paper for routine gravity or Büchner work, glass fiber for gravimetric or solids loading, membranes for defined pore-size or sterile work, ultrafiltration for concentrating molecules by molecular weight Buying the wrong format is the most common mistake, and no grade within that format can make up for it.
Retention rating. Membranes and syringe filters use absolute pore size (0.2/0.22 µm sterilizing, 0.45 µm clarifying); papers and glass fiber use nominal particle retention A nominal retention figure on paper is not comparable to an absolute membrane pore size.
Chemical compatibility. Check the filter material against your solvent, pH and temperature An incompatible material can swell, dissolve or leach extractables into your filtrate.
Method or standard callout. If an SOP or standard method names a grade, buy that grade Results are only comparable when everyone uses the same filter.

Where to find Whatman

Fisher Scientific
Sigma-Aldrich
The Lab Depot

Shops seen in search results on November 6, 2026. A shop missing here may sell it too. Nothing was checked by a person.

Brands that matter

Whatman (Cytiva): Reference grades for filter paper and glass fiber; also sells membranes and syringe filters.
MilliporeSigma (Merck Millipore): Strong in membranes, syringe filters, sterile vacuum filters and Amicon ultrafiltration.
Pall: Acrodisc syringe filters and a broad membrane and ultrafiltration range.
Sartorius: Membranes and Vivaspin centrifugal concentrators.
Thermo Scientific Nalgene: Disposable bottle-top and filter-unit systems.
Corning: Sterile vacuum and bottle-top filter systems for cell culture.

What to avoid

Unbranded filters with no stated retention rating or material
Filters labelled 'sterile' that list no sterilization method and no lot traceability, for cell culture work

Questions

Is 0.2 µm the same as 0.22 µm?

In practice yes. Both are used for sterilizing-grade membranes, and the label varies by manufacturer.

Categories in Lab Filters

Bottletop Lab Filters — AI pick (line): Thermo Scientific Nalgene Rapid-Flow bottle top filters
Glass Fiber Lab Filters — AI pick (line): Whatman Grade GF/C
Lab Filter Membranes — AI pick (line): MilliporeSigma Durapore PVDF membrane filters
Qualitative Lab Filter Paper — AI pick (line): Whatman Grade 1
Quantitative Lab Filter Paper — AI pick (line): Whatman Grade 42
Syringe Lab Filters — AI pick (line): MilliporeSigma Millex-GP (PES, 0.22 µm)
Ultrafiltration Lab Filters — AI pick (line): MilliporeSigma Amicon Ultra centrifugal filters
Air Sampling Lab Filters — How to choose
Centrifugal Lab Filters — AI pick (line): Corning Costar Spin-X centrifuge tube filters
Inline Lab Filters — How to choose
Lab Cell Strainers — AI pick (line): Corning Falcon cell strainers

All of Filtration