Determination of Partial Solubility Parameters of Lactose by Gas-Solid Chromatography

On the basis of the Snyder/Karger-Hansen interaction model, where ΔEA=Vi(δid δjd + δin δjn), the partial solubility parameters of a solid used as the stationary phase may be determined through gas-solid chromatography by null-injection of solutes with known solubility parameters. Using n-decane, acetonitrile, and 1-pro-panol as molecular probes, the values found for unhydrated lactose were 9.6, 12.8, 11.3, and 19.5 (cal1/2/cm3/2) for δd, δp, δn, and δt, respectively; relative standard errors were better than 3%. The choice and the minimum number of the best molecular probes were determined by optimization of the experimental matrix according to the D-criterion, which permits considerable reduction of experimental time yet enhances total precision.