Adjusting Column Length During Gas Chromatography

Kade L. Shepherd & Kevin B. Thurbide from the University of Calgary in Canada developed a novel method for externally adjusting the column length during gas chromatography (GC). Their findings were published in Chromatographia (1).

Female scientist in a white lab coat putting vial with a sample for an analysis on a gas chromatograph in biomedical lab | Image Credit: © BGStock72 - stock.adobe.com

The technique involves controlled dehydration of a water stationary phase off a capillary column wall made of stainless steel. The solution is then removed by the carrier gas. By halting dehydration (via adding water to the system) at specified times, partial column coating lengths are created. For example, dehydrating half of the water coating away results in half of the coated column remaining. This would then act analogous to a half column length in separations. The scientists concluded that direct and effective reduction in analyte retention time stems from shortening a column’s length.

Different column adjustable lengths were demonstrated as part of the experiment, from ¾ to 1/10 of a full column. These experiments allowed proper stability in maintaining new column lengths to be realized, since analyte retention times only varied by around 1% relative standard deviation (RSD) for most of the examined lengths and temperatures. Further, the scientists concluded that column length could be predictably adjusted using system dehydration time, with changes happening in minutes. The method itself shows promise, specifically for adjusting column length in situ to accommodate various samples during GC operation.

Reference

(1) Shepherd, K. L.; Thurbide, K. B. A Method to Externally Adjust the Column Length in Gas Chromatography Using a Water Stationary Phase. Chromatographia 2023. DOI: https://doi.org/10.1007/s10337-023-04299-4