To improve productivity with the lowest cost, many labs are optimizing their current GC methods rather than purchasing new instruments. When looking to optimize column dimensions, it is important to consider column phase ratio (β) to ensure that selectivity will remain the same. For a chromatographic column, phase ratio Φ is defined as the ratio between the volume of the stationary phase Vst and the void volume of the column V0, and it is an important parameter characterizing the HPLC process. The new phase ratio variation method is described which represents a convenient way for the determination of gas-liquid partition coefficients for practical purposes, utilizing equilibrium headspace-gas chromatography (EHS-GC). Document Type: Technical Notes Industries: Phase ratio Φ for an HPLC column is a common parameter being defined as the ratio between the volume of the stationary phase V(st) and the void volume of the column V0.

The ratio of the volume of the mobile phase to that of the stationary phase in a column: \[\beta = \frac{V_{0}}{V_{\text{s}}}\] In the case of open-tubular columns the geometric internal volume of the tube (\(V_{\text{c}}\)) is to be substituted for \(V_{0}\).