Coupled column

Various studies have compared the thermally coupled arrangement in Fig. 5.166 with a conventional arrangement using simple columns on a stand-alone basis. These studies show that the thermally coupled arrangement in Fig. 5.166 typically requires 30 percent less energy than a conventional arrangement using simple columns. The fully thermally coupled column in Fig. 5.166 also... 

Column pipe coupling Guide spider Line Shalt Line Shalt coupling Column pipe... 

Coupling Columns or Using Mixed-Bed Columns to Extend the Molecular Weight Range... 

Zorbax PSM Bimodal and Trimodal columns are packed with mixed pore-size packing to achieve linear size separations over a broad molecular weight range (Table 3.3). Zorbax PSM Bimodal columns are packed with PSM 60 and PSM 1000 particles, and Trimodal columns contain PSM 60, PSM 300, and PSM 3000 particles (Fig. 3.4). Carefully selecting and mixing different pore-size particles in columns provide much better linearity than coupling columns that are each packed with single pore-size particles. 

Figure 1.5 Representation of a coupled column system consisting of a primary column and two secondary columns (reproduced with permission from reference (30)).

Most developments in the past two decades, however, have involved coupled column systems which are much more amenable to automation and more readily permit quantitative measurements, and such systems form the subject of this present book. A review on two-dimensional GC was published (43) in 1978 (and recently updated (29)), and the development by Liu and Phillips in 1991 of comprehensive 2D GC marked a particular advance (33). The fundamentals of HPLC-GC coupling have been set out (37) with great thoroughness by Grob. Other work on a number of other aspects of multidimensional chromatography have also been extensively reviewed (44,45). 

Figure 4.1 Schematic diagram of a coupled column system. The first column (ID) is connected to the second column (2D) tlirough the interface or valve system. The interface can be a diiect coupling, a live T-union, a complex multiport valve, or a thermal or cryogenic modulation system. The stimulus can be the switching of the valve, abalancing pressure to divert flow towards 2D, an added flow that is used in pressure tuning, or the drive mechanism for the modulator. The line to detector 1 will normally be a non-retaining section of column. In a two-oven system, ID and 2D will be in different ovens the dotted line indicates separately heated zones.

LC-LC coupling systems are also employed to perform separations requiring very large plate numbers. However, it has been demonstrated (see equation (5.20) that for coupled columns peak capacity increases linearly with the square root of n... 

E. A. Hogendoom and P. van Zoonen, Coupled-column reversed-phase liquid cliro-matogr-aphy in envuonmental analysis , J. Chromatogr. 703 149-166 (1995). 

G. S. Rule, A. V. Moi dehai and J. Henion, Determination of carbofuran by on-line immunoaffinity cliromatography with coupled-column liquid chromatography/mass spectrometiy . Aim/. Chem. 66 230-235 (1994). 

J. Cai and J. Henion, Quantitative multi-residue determination of /3-agonists in bovine urine using on-line immunoaffinity extr action-coupled column packed capillary liquid cliromatogr aphy-tandem mass spectr ometry , 7. Chromatogr. 691 357-370 (1997). 

J. C. Giddings, Plate height of nonuniform cliromatographic columns. Gas compression effects, coupled columns and analogous systems . Anal. Chem. 35 353-356 (1963). 

Figure 8.1 Coupled column liquid clrromatographic system in which compounds are passed from the primary column to secondary columns in a time At,.

E. E. Johnson, R. Gloor and R. E. Majors, Coupled column chromatography employing exclusion and a reversed phase. A potential general approach to sequential analysis , J. Chromatogr. 149 571-585 (1978). 

Figure 11.1 (a) Schematic representation of a coupled-column LC system for sameridine... 

Figure 11.4 Chromatograms of plasma samples on a silica-chiralcel OJ coupled column system (a) plasma spiked with oxprenolol (internal standard) (b) plasma spiked with 040 p-g/ml metyrapone and 0.39 p-g/ml metyrapol (racemate) (c) plasma sample obtained after oral administration of 750 mg metaiypone. Peaks are as follows 1, metyrapone 2, metyrapol enantiomers 3, oxprenolol. Reprinted from Journal of Chromatography, 665, J. A. Chiarotto and I. W. Wainer, Determination of metyrapone and the enantiomers of its chfral metabolite metyrapol in human plasma and urine using coupled achfral-chfral liquid cltro-matography, pp. 147-154, copyright 1995, with permission from Elsevier Science.

E. Eklund, C. Norsten-Hoog and T. Arvidsson, Determination of free concentration of sameridine in blood plasma by ultr afiltration and coupled-column liquid chr omatogra-phy ,7. Chromatogr. B10 195-200(1998). 

L. B. Nilsson, High sensitivity determination of the remoxipride hydroquinone metabolite NCQ-344 in plasma by coupled column reversed-phase liquid cliromatography and electi ochemical detection , Biomed. Chromatogr. 12 65-68 (1998). 

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