The non-modulated transfer of total effluent for serially coupled columns in gas chromatography

The non-modulated transfer (NMT) of the total effluent of the separation of polychlorinated biphenyls (PCBs) on two columns coupled in series has been studied. A non-polar poly(5%-phenyl-95%-methyl)siloxane column (40 m × 100 μm × 0.1 μm) and a polar 70%-cyanopropyl-polysilphenylene-siloxane column (4 m × 0.1 mm × 0.1 μm) were used as 1D and 2D columns, respectively. The effluents from both the 1D column and the 1D + 2D column series were monitored independently by two FIDs. Data from the 1D and 1D + 2D integration reports were used to evaluate the NMT experiment. 1D retention times, tR,i,D1, were directly accessible from 1D integration report while 2D retention times, tR,i,B, were calculated for all corresponding peak pairs from 1D and 1D + 2D integration reports as a difference tR,i,D2=tR,i,D1+D2−tR,i,D1. Search for corresponding peaks of PCB congeners in the 1D and 1D + 2D chromatograms is elucidated in detail on standard PCB samples and on PCB congeners present in the technical formulation Arochlor 1242. Both retention times (tR,i,D1 and tR,i,D2) as well as peak widths at half height (wh,i) and peak heights (hi) obtained from integration reports were used to construct 2D and 3D images for PCB NMT separations on serially coupled columns. The performance of the NMT procedure is illustrated by the separation of (i) standard PCB solutions, (ii) a mixture of the 209 PCBs, and (iii) a mixture of Arochlor 1242 and hydrocarbons on the DB-5 + BPX-70 column series.