LCGC UST
|Articles|October 1, 1999

LCGC North America

  • October 1999
  • Volume 17
  • Issue 10
  • Pages: 914–922

Optimizing Separations Using Coupled Columns and Window Diagramming

Author(s)Dean Rood

In this month's "GC Connections," guest columnist Dean Rood writes about optimizing separations using combinations of two columns connected in a series. These coupled column systems produce peak separations that are a combination of separations achieved on each column individually. He describes the geographical window diagramming approach to determining the optimal combination of column lengths for several separations and column combinations and compares the results with those obtained using mixed stationary-phase chemistry.


Related to this article

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 insertion distance for methanol and methylene chloride in GC analysis and confirming that insertion depth strongly affects response and reproducibility.