# Syringe Filter Color Codes: A Quick Identification Guide
The pink filter in your drawer might be nylon at one brand, PVDF at another. Color codes make syringe filter identification fast, but only if you know what the colors mean for your specific brand, and the schemes are not standardized across the industry.
Syringe filter color codes identify either the membrane type or the pore size, depending on the manufacturer. There is no universal color standard, so the printed text on the housing, not the color, is the reliable identifier.
Below you’ll find the common color conventions, why they differ between brands, and a two-second verification habit that prevents the most expensive mistake in sample prep.
What the Colors Actually Encode
Here’s the confusing part: manufacturers chose different coding schemes, and both approaches are common in the wild.
Some brands color by membrane type. A typical scheme looks like this: PES green, PVDF blue, nylon pink or yellow, PTFE white or red, mixed cellulose ester (MCE) blue or yellow. The idea is that you grab a filter by feel and know you’ve got the right chemistry for your solvent.
Other brands color by pore size. Cytiva’s PharmAssure syringe filters are a clear example: the product documentation shows blue housings for 0.2 µm, red/clear for 0.45 µm, and green for 5 µm, with the color pairs printed right in the spec table. That’s a deliberate design so a pharmacist can tell pore sizes apart at a glance, and you can see the scheme on the PharmAssure product page.
So the same physical color can mean two different things depending on whose filter is in your hand. A green housing might mean PES at one vendor and 5 µm at another. This is why color alone should never be your final check.
Common Color Conventions You’ll Encounter
Most HPLC labs converge on a rough de facto pattern for membrane colors, and it helps to recognize it:
• Green: usually PES, the fast-flow, low-protein-binding choice for aqueous and biological samples.
• Blue: often PVDF or MCE, depending on the brand.
• Yellow or pink: commonly nylon, the general-purpose workhorse for HPLC samples.
• White or red: usually PTFE, for aggressive solvents and strong acids.
Treat that list as a hint, never an answer. I once watched a new technician grab what she assumed was a PTFE filter for a chloroform extraction because it was white. It was MCE. The membrane dissolved into the sample, and the “peak” that showed up on the HPLC was actually filter debris. The rerun cost half a day and the incident cost her some confidence.
Major manufacturers publish selection guides and full lineups so you can confirm any code before you order. Thermo Fisher’s filtration section is a good reference point for one large portfolio: Thermo Fisher syringe filters. Phenomenex and Merck publish similar references for their own lines, and Millex filters from Merck carry their own housing conventions: Phenomenex syringe filters and Millex syringe filters.
Why There’s No Industry-Wide Standard
No standards body has ever assigned colors to filter membranes or pore sizes. Each manufacturer developed its own scheme as its product line grew, and by the time the industry noticed the inconsistency, billions of filters had shipped with brand-specific codes.
It also isn’t purely marketing. Housing colors serve real purposes: batch identification on a crowded bench, or picking the right filter out of a lab coat pocket without reading fine print. In hospital pharmacy settings, pore-size coding even supports patient safety.
The lesson is simply that color is a brand-internal convention. Fine for speed within one vendor’s line. Unreliable across vendors.
The Two-Second Verification Habit
Every syringe filter worth buying has its membrane type and pore size printed on the housing. Make reading that print your only identification method, and use color as a shortcut, never as the answer.
My rule: the print must match the method sheet, or the filter doesn’t touch the sample. Ten seconds per filter. Compare that to rerunning a 40-injection sequence because a nylon membrane extracted plasticizers into your mobile phase front.
If you’re choosing between membrane chemistries in the first place, color won’t help you; the chemistry will. Our nylon vs PTFE vs PVDF vs PES comparison walks through solvent compatibility and protein binding for each. And if pore size is your open question, the 0.22 vs 0.45 µm guide covers when each is the right call.
Building a Mistake-Proof Filter Station
If multiple brands share your bench, a little organization prevents most mix-ups:
• Store by chemistry, not by color. Bin the nylon filters together regardless of brand, bin the PTFE together, and so on.
• Label the bins with the chemistry and pore size in text. No color-only labels.
• Keep one brand per chemistry where you can. Two nylon vendors on one shelf doubles the chance of a code clash.
• Write the membrane on your run log. When a chromatogram looks odd two weeks later, you’ll know what was in the filter path.
These steps take an afternoon to set up. In my experience they pay for themselves the first time a lot change or a new hire arrives, which is to say, almost immediately.
One more practical note: mixed filter stations are also where clogged filters get blamed on samples. If your “0.45 µm” bin quietly contains a 0.22 µm filter from another brand, slow filtration looks like a dirty sample, and someone wastes an hour re-filtering. Our common syringe filter mistakes guide covers that trap and six more worth knowing.
Conclusion
Syringe filter color codes are a convenience, not a standard: some brands code by membrane, some by pore size, and a green housing means different things on different vendors’ products. The printed text on the housing is the only identification you should trust, so make reading it a non-negotiable step before every filtration. Sort your stock by chemistry in labeled bins, keep verification under ten seconds, and you get all the speed of color coding with none of the risk. For your next steps, the 0.22 vs 0.45 µm pore size guide and the membrane chemistry comparison are the two references I’d keep within arm’s reach.
Frequently Asked Questions
Is there a universal color code for syringe filters?
No. Each manufacturer sets its own scheme, and some code by membrane while others code by pore size. Always confirm the membrane type and pore size from the printing on the housing or the product certificate.
What color is a PES syringe filter?
Green is the most common color for PES, but this varies by brand, and at least one major brand uses green to mark a 5 µm pore size instead. Check the printed housing text to be sure of what you’re holding.
Does the color of a syringe filter housing affect the sample?
No, the housing color is just pigment in the plastic and has no chemical effect on the filtrate. Only the membrane material, pore size, and housing resin composition matter for your sample’s chemistry.
How can I tell what membrane my unlabeled syringe filters are?
You can’t reliably, and using them in a validated method is a gamble. Check the original box or certificate for the lot, or run a small solvent compatibility test: hydrophobic PTFE won’t pass water, while MCE swells or dissolves in strong organics. When in doubt, buy fresh with printed housings.
Why do some brands use color for pore size instead of membrane type?
It reflects the user base. Hospital pharmacy filters like Cytiva’s PharmAssure line serve clinicians who need to distinguish 0.2 µm from 5 µm for drug administration safety, so pore size drives the coding. Analytical labs more often need to distinguish membrane chemistry, so those brands code by membrane.
