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News|Articles|June 25, 2026

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  • June 2026
  • Volume 22
  • Issue 2
  • Pages: 23–25

Can You Use a Polyethylene Glycol (PEG) Phase for GC–MS?

Author(s)Chris English

Practical GC in gas chromatography: learn how PEG column bleed affects MS sensitivity, and when polar analytes still quantify reliably.

One of the most common stationary phases for gas chromatography (GC) is the polyethylene glycol (PEG) or “wax” columns. They are highly polar when compared to polydimethylsiloxane (PDMS) phases, such as a 5-type column
(5% diphenyl/95% dimethyl polysiloxane). The carbon-carbon–oxygen backbone is highly selective for alcohols, glycols, aldehydes, and ethers, offering unique selectivity unavailable in other phases. While many analysts avoid using a mass spectrometer (MS) with a PEG phase, this article will explore the differences in sensitivity, selectivity, reproducibility,
and bleed compared with a traditional PDMS-based column.

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Figure 2. Split injection used to measure triplicate test of MTBE, hexane, o-xylene, and 1-methylnaphthalene comparing different solvents (methanol, methylene chloride) and column insertion distances starting with 0.5 mm, 5.0 mm, 10.0 mm, 15 mm, and 20.0 mm. Methanol had the best performance at the 5.0 mm insertion distance and methylene chloride looked slightly better at the 0.5 mm. We would still recommend not going below the 5.0 mm manufacturer recommended insertion distance.
Revisiting Column Insertion Distance
Revisiting insertion distance for methanol and methylene chloride in GC analysis and confirming that insertion depth strongly affects response and reproducibility.
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