USP L3 column: Bare silica
Unmodified porous silica particles of 1.5-10 um, or a monolithic silica rod.
Mode: normal-phase Typical pH range: about 2-7.5 (bare silica dissolves at high pH)
Typical uses
- Normal-phase assays with non-aqueous eluents (e.g. fat-soluble vitamins)
- Separation of positional isomers
- HILIC of polar basic compounds
Common sizes (length x internal diameter, particle size)
- 250 x 4.6 mm, 5 um
- 150 x 4.6 mm, 5 um
Very sensitive to water content of the mobile phase in normal-phase mode; equilibrate well.
Example columns sold as USP L3
From the makers' own USP code lists and product pages, checked October 2026. Examples only, not an endorsement. Columns with the same code can still differ in selectivity; if the monograph names a column in its notes, start with that one.
| Maker | Product family | Particle | pH range |
|---|---|---|---|
| Waters | Atlantis HILIC Silica | fully porous silica 3/5 um | not stated in source |
| Phenomenex | Luna Silica(2) | fully porous silica 3/5/10/15 um | 2-7.5 |
| Thermo Fisher Scientific | Hypersil GOLD Silica | fully porous silica 1.9/3/5 um | 2-8 |
| Agilent | Pursuit Si | fully porous silica | not stated in source |
| Merck (Supelco) | Purospher STAR Si | fully porous silica | not stated in source |
| Restek | Raptor HILIC-Si | SPP (core-shell) silica 2.7 um | 2-8 |
| Macherey-Nagel | NUCLEODUR SiOH | fully porous silica | not stated in source |
| Avantor (ACE) | ACE SIL | fully porous silica 2/3/5/10 um | 2-7 |
| Nacalai Tesque (Cosmosil) | COSMOSIL SL-II | fully porous silica | not stated in source |
| Welch Materials | Ultisil Silica (SiO2) | fully porous silica | not stated in source |
10 makers listed, so a tender written by USP code stays open to competition.
Tender wording (brand-neutral)
HPLC column with USP L3 packing (Bare silica), 250 x 4.6 mm, 5 um (length x internal diameter, particle size); stainless-steel or equivalent hardware with standard fittings; recommended pH and temperature range to be stated by the bidder; each column supplied with its certificate of analysis and test chromatogram, batch/lot number and serial number; shelf life not less than 2 years from delivery; any make meeting the USP L3 designation and the stated dimensions is acceptable.
Size:
Changing length or particle size
You can keep the USP L3 packing and use a different length, particle size or diameter within the harmonized USP 621 limits. Check your columns with the calculator.
Related column types
L8 Amino (aminopropyl silane) | L20 Diol
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