Chromatography guide: HPLC and GC columns, vials and sample preparation

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HPLC guard column cartridge with phenyl-hexyl phase for liquid chromatography | Luminix Health

Start column selection from the analyte: polarity, size and charge decide the stationary phase; your instrument pressure limit and detector decide particle size and column diameter. Clean samples, the right vial and filtered solvents protect both.

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Last updated: 24 October 2026

HPLC and UHPLC columns

Phase Best for Note
C18 (octadecyl) Most small molecules, the default starting point Choose an end-capped or polar-embedded C18 for bases
C8 Less retention, faster elution of hydrophobic compounds Useful for peptides and steroids
Phenyl-hexyl Aromatic compounds, alternative selectivity Good second column in method development
HILIC Very polar compounds that elute too early on C18 High organic mobile phase, MS-friendly
Ion exchange / size exclusion Proteins, oligonucleotides, charged species Check pH and salt limits

Typical values for guidance; always check the manufacturer's data sheet. Sources: see Official sources below.

Fully porous 5 µm particles suit conventional HPLC; 3 µm and core-shell 2.7 µm give more efficiency at moderate pressure; sub-2 µm needs UHPLC. A 4.6 × 150 mm column is a common standard; 2.1 mm internal diameter saves solvent and suits LC-MS. Fit a guard column to extend column life.

GC columns

For capillary GC, choose the phase by polarity: 100 % dimethylpolysiloxane for non-polar analytes, 5 % phenyl as the general-purpose choice, mid-polarity cyanopropyl phases for pesticides and solvents, and polyethylene glycol (WAX) for alcohols, acids and flavours. A 30 m × 0.25 mm × 0.25 µm column is the usual starting point; a thicker film retains volatile compounds better.

Vials, filters and solvents

  • 2 ml autosampler vials come as screw (9 mm or 8-425), crimp or snap types; check what your autosampler accepts.
  • Use amber vials for light-sensitive samples and inserts or low-volume vials for small samples.
  • PTFE/silicone septa suit most methods; pure PTFE resists aggressive solvents but does not reseal after multiple injections.
  • Filter samples through 0.45 µm for HPLC and 0.2 µm for UHPLC or sub-2 µm columns.
  • Use HPLC- or LC-MS-grade solvents and ISO 3696 grade 1 water.

See our Laboratory Guide for syringe filter selection in depth.

Frequently asked questions

Which HPLC column should I start with?

For most small molecules, a C18 column of 4.6 × 150 mm with 3 or 5 µm particles. Switch to phenyl-hexyl or HILIC if selectivity or retention is not sufficient.

Why is my column back pressure rising?

Usually because particles or precipitated buffer block the inlet frit. Filter samples and mobile phases, use a guard column, and flush buffers out with water before switching to high organic.

Screw, crimp or snap vials?

Screw caps are easy and reliable, crimp caps give the best seal for volatile samples and long sequences, and snap caps are fast but seal less tightly. The autosampler decides first.

C18, C8 or phenyl: which phase?

C18 gives the most retention and is the default. C8 retains less, which shortens run times for hydrophobic analytes. Phenyl phases add π–π selectivity for aromatic compounds.

Which GC column dimensions are standard?

30 m × 0.25 mm internal diameter × 0.25 µm film suits most methods. Use a thicker film for very volatile analytes and a narrower bore or shorter column for faster runs.

Which syringe filter should I use before HPLC?

0.45 µm for columns with 3 µm particles or larger, 0.2 µm for UHPLC and sub-2 µm particles. PTFE suits organic solvents, PES and nylon aqueous samples, and regenerated cellulose covers both with low binding.

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Official sources