HPLC column selector: find the right column and USP L-code

Answer a few questions about what you are testing and the tool proposes the column type (USP L-code), a size that suits your HPLC or UHPLC system, and brand-neutral wording you can put in a tender. Free for drug testing laboratories, pharma QC and research labs.

This is decision support. For a pharmacopoeial test, always use the column named in the current official monograph (BP, USP or Ph. Eur.); within that column type, USP 621 allows limited changes to length, particle size and diameter.

The most-used column types in pharmaceutical testing

USP code	Column type	Mode	Typical use
L1	C18 (octadecyl silane)	reversed-phase	Assay and impurity tests for most small-molecule drugs
L3	Bare silica	normal-phase	Normal-phase assays with non-aqueous eluents (e.g. fat-soluble vitamins)
L7	C8 (octyl silane)	reversed-phase	Assays of hydrophobic drugs that are too strongly retained on C18
L8	Amino (aminopropyl silane)	normal-phase	Sugars and sugar alcohols with acetonitrile-water (HILIC-type)
L9	SCX on silica	ion-exchange	Cation-exchange separation of basic drugs and amines
L10	Cyano (CN, nitrile)	reversed-phase	Alternative selectivity to C18/C8 in reversed-phase mode
L11	Phenyl	reversed-phase	Aromatic and conjugated compounds (pi-pi selectivity)
L17	SCX resin, H+ form (organic acid / ion-exclusion)	ion-exchange	Organic acids by ion-exclusion with dilute acid eluent
L20	Diol	normal-phase	Normal-phase and HILIC separations
L21	PS-DVB polymer (rigid)	reversed-phase	Reversed-phase methods needing high or low pH
L26	C4 (butyl silane)	reversed-phase	Peptides and proteins (wide-pore versions)
L34	SCX resin, Pb2+ form (sugar alcohols)	ion-exchange	Sorbitol, mannitol, maltitol and other polyols with water eluent
L43	PFP (pentafluorophenyl)	reversed-phase	Halogenated compounds and positional isomers
L60	Polar-embedded alkyl amide, endcapped	reversed-phase	Basic drugs with better peak shape than plain C18

Buying columns by tender

Write columns by USP code and size, never by brand: for example "USP L1, 250 x 4.6 mm, 5 um". Ask for the certificate of analysis and test chromatogram with each column, a minimum shelf life, and accept any make that meets the USP designation. Each column page below gives ready tender wording. For instruments, use the MedInfoBase Spec Builder.

All USP column codes

L1 C18 (octadecyl silane)
L2 C18 on pellicular silica (30-50 um)
L3 Bare silica
L4 Silica, pellicular (30-50 um)
L5 Alumina, pellicular (30-50 um)
L6 SCX, sulfonated fluorocarbon on pellicular core
L7 C8 (octyl silane)
L8 Amino (aminopropyl silane)
L9 SCX on silica
L10 Cyano (CN, nitrile)
L11 Phenyl
L12 SAX, quaternary amine on pellicular core
L13 C1 (trimethylsilane)
L14 SAX on silica
L15 C6 (hexyl silane)
L16 C2 (dimethyl silane)
L17 SCX resin, H+ form (organic acid / ion-exclusion)
L18 Amino + cyano on silica
L19 SCX resin, Ca2+ form (sugars)
L20 Diol
L21 PS-DVB polymer (rigid)
L22 Cation-exchange polystyrene gel (sulfonic)
L23 SAX polymethacrylate/polyacrylate gel
L24 Polyvinyl alcohol on silica
L25 Polymethacrylate SEC, water-soluble polymers (MW ~100-5000)
L26 C4 (butyl silane)
L27 Silica, porous (30-50 um)
L28 Mixed-mode silica: amine anion exchanger + C8
L29 Polybutadiene-coated alumina (RP)
L30 Ethyl silane (C2)
L31 Hydroxide-selective SAX, latex on macroporous core (8.5 um)
L32 Chiral ligand exchange (L-proline copper)
L33 SEC silica for dextrans (4-500 kDa)
L34 SCX resin, Pb2+ form (sugar alcohols)
L35 Zirconium-stabilized silica with diol (SEC, 150 A)
L36 Pirkle chiral (DNB-phenylglycine)
L37 Polymethacrylate SEC for proteins (2-40 kDa)
L38 Methacrylate SEC, water-soluble samples
L39 Hydrophilic polyhydroxymethacrylate gel (SEC)
L40 Cellulose tris(3,5-dimethylphenylcarbamate), coated
L41 Alpha1-acid glycoprotein (AGP) chiral
L42 C8 + C18 mixed on silica
L43 PFP (pentafluorophenyl)
L44 Mixed-mode silica: sulfonic cation exchanger + C8
L45 Beta-cyclodextrin (hydroxypropyl) chiral
L46 SAX, latex-agglomerated PS-DVB (9-11 um)
L47 High-capacity microporous SAX (trimethylamine, 8 um)
L48 Sulfonated PS core with anion-exchange microbeads
L49 Polybutadiene-coated zirconia (RP)
L50 Mixed-mode resin: RP + strong anion exchange
L51 Amylose tris(3,5-dimethylphenylcarbamate), coated
L52 SCX silica (sulfopropyl / sulfoethyl)
L53 WCX resin, carboxylic/phosphonic grafted EVB-DVB (cations IC)
L54 Dextran-agarose SEC
L55 SCX silica, polybutadiene-maleic acid coated
L56 C3 (propyl silane)
L57 Ovomucoid chiral protein
L58 SCX resin, Na+ form (sugars/oligosaccharides)
L59 Protein SEC on coated silica/hybrid (5-7000 kDa)
L60 Polar-embedded alkyl amide, endcapped
L61 Hydroxide-selective SAX, latex on microporous core (13 um)
L62 C30
L63 Teicoplanin glycopeptide chiral
L64 Strong-base anion resin, Cl- form (45-180 um)
L65 Strong-acid cation resin, H+ form (coarse)
L66 Crown ether chiral, (S)-18-crown-6
L67 Polymer C18 (vinyl alcohol copolymer)
L68 Alkyl amide, not endcapped
L69 SAX, latex on EVB-DVB (about 6.5 um)
L70 Cellulose tris(phenylcarbamate), coated
L71 Rigid spherical polymethacrylate (4-6 um)
L72 Phenylglycine urea chiral
L73 Rigid polydivinylbenzene (5-10 um)
L74 SAX, macroporous core with quaternary ammonium layer (7 um)
L75 Bovine serum albumin (BSA) chiral
L76 WCX silica, polybutadiene-maleic acid coated
L77 WCX resin, carboxylic EVB-DVB (6-9 um)
L78 Mixed-mode silica: RP (>C8) + anion exchange
L79 Human serum albumin (HSA) chiral
L80 Cellulose tris(4-methylbenzoate), coated
L81 Hydroxide-selective SAX, latex on porous core (9 um)
L82 Polyamine on polyvinyl alcohol
L83 Hydroxide-selective SAX, latex on microporous core (10.5 um)
L84 WCX resin, carboxylic EVB-DVB (5 um)
L85 Mixed-mode silica: RP (>C8) + weak cation exchange
L86 Pentahydroxy polar ligand on core-shell silica (HILIC)
L87 C12 (dodecyl silane)
L88 Vancomycin glycopeptide chiral
L89 Polymethacrylate SEC, water-soluble polymers (MW ~100-3000)
L90 Amylose tris[(S)-alpha-methylbenzylcarbamate], coated
L91 SAX, monodisperse porous PS-DVB (10 um)
L92 SAX, macroporous core with alkanol quaternary ammonium
L93 Cellulose tris(3,5-dimethylphenylcarbamate), RP chiral
L94 SAX, latex on microporous core (15 um)
L95 Pentahydroxy polar ligand on porous silica (HILIC)
L96 Aqueous-compatible RP (polar endcapped alkyl)
L97 WCX, macroporous core with carboxylic groups (5.5 um)
L98 WCX, microporous core with carboxylic groups (8 um)
L99 Amylose tris(3,5-dimethylphenylcarbamate), immobilized
L100 Bilayer cation/anion latex on resin core
L101 Cholesteryl bonded phase
L102 Whelk-O 1 type chiral (Pirkle)
L103 Hydroxide-selective SAX, porous core (7.5 um)
L104 Triazole-bonded silica (HILIC)
L105 SAX, supermacroporous core with latex (9 um)
L106 WCX, macroporous EVB-DVB with carboxylic/phosphonic groups
L107 Cellulose tris(4-methylbenzoate), RP chiral
L108 Cellobiohydrolase (CBH) chiral protein
L109 Porous graphitic carbon
L110 SAX, latex on microporous core (13 um)
L111 Polyamine on silica
L112 Hydroxide-selective SAX, latex on porous core (8.5 um)
L113 Hydroxide-selective SAX, latex on porous core (7.5 um)
L114 Zwitterionic sulfobetaine on silica
L115 SAX, latex on EVB-DVB
L116 SAX for nucleic acids (sulfonated core + amine microbeads)
L117 Crown ether chiral, (R)-18-crown-6 type)
L118 Aqueous-polymerized C18 on silica
L119 Cellulose tris(3,5-dichlorophenylcarbamate), immobilized
L120 Hydroxide-selective SAX, latex on microporous core (13 um)
L121 Hydroxide-selective SAX, hyperbranched (11 um)
L122 Zwitterionic sulfobetaine on polymer
L123 Cellulose tris(3-chloro-4-methylphenylcarbamate), coated
L125 WCX on polyvinyl alcohol, polybutadiene-maleic acid
L126 Amylose tris(3-chlorophenylcarbamate), immobilized
L128 PS-DVB GPC packing (organic, MW ~200-2,000,000)
L130 Cellulose tris(3,5-dimethylphenylcarbamate), coated, 10 um
L131 Amylose tris(3,5-dichlorophenylcarbamate), immobilized
L134 Amylose tris(3-chloro-4-methylphenylcarbamate), immobilized
L135 Amylose tris(3-chloro-5-methylphenylcarbamate), immobilized

Questions

What does USP L1 mean?

L1 is the USP code for octadecyl silane (C18) packing: the most widely used reversed-phase HPLC column. Many makers sell L1 columns; they are not identical, so a monograph may name a specific column in its notes.

Can I use a column with a different length or particle size?

Under harmonized USP 621 and Ph. Eur. 2.2.46 you may change length and particle size if the length-to-particle-size ratio (L/dp) stays within -25% to +50% of the original, keep the same packing type, rescale the flow, and still pass system suitability.

Which column should I start with for a new method?

For most small-molecule drugs, an end-capped C18 (USP L1), 150 x 4.6 mm, 3-5 um on HPLC or 100 x 2.1 mm, under 2 um on UHPLC, at low pH. Change to C8, phenyl, PFP, HILIC or ion-exchange when retention or selectivity is not right.

How should columns be written in a government tender?

By USP code, dimensions and particle size, with a certificate of analysis and test chromatogram, a shelf life and "any make meeting the designation is acceptable". Avoid brand names unless you buy a spare part for a specific instrument.