Prototype of an Interface for Hyphenating Distillation with Gas Chromatography and Mass Spectrometry

Abstract

Chemical analysis of complex matrices-containing hundreds of compounds-is challenging. Two-dimensional separation techniques provide an e cient way to reduce complexity of mixtures analyzed by mass spectrometry (MS). For example, gasoline is a mixture of numerous compounds, which can be fractionated by distillation techniques. However, coupling conventional distillation with other separations as well as MS is not straightforward. We have established an automatic system for online coupling of simple microscale distillation with gas chromatography (GC) and electron ionization MS. e developed system incorporates an interface between the distillation condenser and the injector of a fused silica capillary GC column. Development of this multidimensional separation (distillation-GC-MS) was preceded by a series of preliminary o -line experiments. In the developed technique, the components with di erent boiling points are fractionated and instantly analyzed by GC-MS. e obtained data sets illustrate dynamics of the distillation process. An important advantage of the distillation-GC-MS technique is that raw samples can directly be analyzed without removal of the non-volatile matrix residues that could contaminate the GC injection port and the column. Distilling the samples immediately before the injection to the GC column may reduce possible matrix e ects-especially in the early phase of separation, when molecules with di erent volatilities co-migrate. It can also reduce losses of highly volatile components (during fraction collection and transfer).e two separation steps are partly orthogonal, what can slightly increase selectivity of the entire analysis.

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