Separation of m-Xylene and p-Xylene by Gas Chromatography

Abstract

CONSIDERABLE interest has recently been centred on the difficult separation of m-xylene and p-xylene by gas chromatography both from the point of view of the analysis of mixtures containing these isomers and the assessment of the performance of high efficiency columns. Martin and James¹ predicted some years ago that it should be possible to achieve a separation using benzyldiphenyl as a stationary phase with a high-efficiency column and this was recently demonstrated by Zlatkis². Similar partial separations have been described^3–5 with other stationary phases in long packed columns and by using long capillary columns⁶. Langer⁷ has described the use of tetrahalophthalic esters as stationary phases which cause the meta isomer to be eluted before the para—the reverse of the usual order. (In an earlier paper⁸, the relative retention volumes of p-xylene and m-xylene were incorrectly quoted in the reverse order for both n-hexatriacontane and benzyldiphenyl.)