Led by Pascal Cardinael and fellows from the University of Rouen-Normandy (Rouen, France), a new study published in the Journal of Chromatography Open explores new stationary phases for during high-temperature gas chromatography (HTGC) analysis (1).
MONT-SAINT-AIGNAN, NORMANDY, FRANCE - JULY 4, 2007, University of Rouen Normandy, "UFR Lettres et Sciences humaines", Faculty of Literature and Human Sciences, outside view of the amphitheatre | Image Credit: © Pvince73 - stock.adobe.com
High-temperature gas chromatography (HTGC) is a routine technique for analyzing high boiling compounds, which are eluted from a column with oven cycling up to > 400 ºC, while analytes are measured using flame ionization detection (FID) (2). One of the most important components for this type of analysis is the column and the thermal stability of the stationary phase coated inside. While efforts have been made to create high-temperature stationary phases that can withstand temperatures above 380 ºC, commercial high-temperature stationary phase availability is limited. This is mostly due to the difficulty of obtaining materials that are stable at high temperatures while remaining as liquid stationary phases for HTGC.
In this study, the researchers synthesized a series of thermoresistant polysiloxanes containing silarylene units and macrocyclic silicon phthalocyanine (Pc) units (PS-1–PS-6). The Pc was linked to polymer chains through siloxane central group, which have two covalent bonds with two nitrogen atoms of the macrocycle and two covalent bonds with the polymer chain. The sol–gel process (where solid nanoparticles dispersed in a liquid [a sol] agglomerate together to form a continuous three-dimensional network extending throughout the liquid [a gel]) was used to create polymeric chains with a random arrangement of monomers and OH-terminated chains (3). Thermogravimetric analyses showed that the polymers were stable at high temperatures, exhibiting a weight loss of 10% between 384 and 442 °C during heating.
When coated as GC stationary phases, polymers PS-1, PS-2 and PS-5 showed good film-forming ability. The PS-1 and PS-5-prepared columns had 3300 and 3800 plates m−1, respectively, as determined with pentadecane at 130 °C for fused silica capillary columns with an internal diameter of 250 µm, a film thickness of 0.25 µm and a length of 10 m. Polarity was estimated as moderate while stationary phases were shown achieving very good separation of polycyclic aromatic hydrocarbons (PAHs) and essential oils. Additionally, the columns displayed excellent high temperature stability with very low bleeding (17.0 pA at 420 °C).
Repeated injections of high boiling analytes showed PS-1 to be the most stable stationary phase at very high temperatures. This stems from the smallest decrease of retention times (9.2 s) being observed after 50 successive injections (temperature program from 40 °C (hold 3 min) at 7 °C/min to 420 °C (hold 2 min). It was also demonstrated that PS-1 was more stable that pre-existing commercial high-temperature columns. Additionally, they displayed notable selectivity for analytes with a wide range of polarity, including n-alkanes, PAHs and essential oils. This suggests that Pc-based stationary phases hold great potential for HTGC applications. Additionally, these stationary phases can enable researchers to analyze the polar sections of bio-oils obtained through the pyrolysis of plant or plastic samples.
(1) Ţînţaş, M-L.; Peulon-Agasse, V.; Piparo, M.; et al. New Silicon Phthalocyanine-Containing Polysiloxanes as Stationary Phases for High-Temperature Gas Chromatography Analysis. J. Chromatogr. Open 2025, 7, 100221. DOI: 10.1016/j.jcoa.2025.100221
(2) Sutton, P. A.; Rowland, S. J. High Temperature Gas Chromatography–Time-of-Flight-Mass Spectrometry (HTGC–ToF-MS) for High-Boiling Compounds. J. Chromatogr. A 2012, 1243, 69–80. DOI: 10.1016/j.chroma.2012.04.044
(3) The Sol-Gel Process. Aerogel.org 2025. https://www.aerogel.org/?p=992 (accesse 2025-5-29)
