The use of high-speed multicapillary column in comprehensive two-dimensional gas chromatography with flow modulation

Abstract

The possibility to use multicapillary gas-chromatography column (MCC) as the second-dimension column in comprehensive two-dimensional gas chromatography (GC×GC) has been demonstrated. Dependences of the efficiency on the carrier gas volumetric flow rate were studied for capillary columns (CC) HP-5 and ZB-WAX of length 5m and multicapillary columns of length 0.25m with stationary phases OV-73 and Carbowax 20M. For standard capillary columns, the maximum efficiency is reached at a flow rate below 2mL/min. In the GC×GC mode, a capillary column is operated at a flow rate strongly exceeding the optimal value. Therewith, the efficiency of standard capillary column decreases several-fold, to 1570 theoretical plates for HP-5 and 1000 theoretical plates for ZB-WAX. In the case of multicapillary columns that are used in this paper, the maximum efficiency is reached at the carrier gas velocities above 60mL/min. This allows MCC to be used as the second-dimension column in GC×GC at the optimal flow rate, thus reaching a maximum efficiency of 5900 theoretical plates for MCC with the OV-73 stationary phase and 2800 theoretical plates with Carbowax 20M. The GC×GC separation of aliphatic and aromatic compounds was used to demonstrate that high efficiency of MCC enhances peak resolution in the second dimension as compared to standard capillary column. MCC was shown to be superior in separation of the components with close retention times and substantially differing concentrations.