Chromatography coupled-column

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 12.12 Coupled SEC-RPLC separation of Plioflex rubber stock (a) SEC (b) RPLC ti ace of fraction 1, Wingstay 100 (Eive-peak pattern is representative of diarylphenylenedi-amine isomers) (c) RPLC ti ace of fraction 2, mixed disulfide and MBTS (2,2 -thiobis (ben-zothiazole)). Obtained under the same conditions as given for Eigure 12.11. Reprinted from Journal of Chromatography, 149, E. L. Johnson et al, Coupled column chromatography employing exclusion and a reversed phase. A potential general approach to sequential analysis , pp. 571-585, copyright 1978, with permission from Elsevier Science.

Instead, the idea of Coupled-Column Chromatography was employed (1. Here, this means the manual coll don of fractions from one chromatograph and their reinjection into another. Coll tion of GPC fractions and their analysis by other instruments or re-injection has often been utilized qualitatively in GPC. However, precise quantitative analysis is much less often reported (6). 

Rizzi, A. M. and Plank, C., Coupled column chromatography in chiral separations systems employing P-cyclodextrin phases for chiral separation, /. Chromatogr., 557, 199, 1991. 

Rojkovicova, T., Hrobonova, K., Lehotay, J., Cizmarik, J. (2003a). Coupled column chromatography for separation and determination of enantiomers of phenylcarbamic acid derivatives in serum. Pharmazie 58, 108-110. 

Stalcup, A.M., Faulkner, J.R., Jr, Tang, Y., Armstrong, D.W., Levy, L.W., Regalao, E. (1991). Determination of the enantiomericpurity of scopolamine isolated from plant extract using achiral/chiral coupled column chromatography. Biomed. Chromatogr. 5, 3-7. 

Walhagen, A., Edholm, L.E. (1989). Coupled-column chromatography on immobilized protein phases for direct separation and determination of drug enantiomers in plasma. J. Chromatogr. 473, 371-379. 

The idea of chromatographic CF is the use of timely chromatographic apparatus and technique for this purpose. Basically, it is the application towards copolymer investigation of what is known among chromatographers as multi-dimensional or coupled column chromatography. 

For the investigation of a butadiene-styrene rubber, a set of three SEC columns in series was used 500 x 8 mm, d0 = 150 nm 500 x mm, d0 = 25 nm 800 x 8 mm, d0 = 4 nm, all three with dP = 10 pm. The flow rate was 1 ml/min. The injection amounted to 200 pi of a 2 % solution from which the carbon black had been removed. Although the additives of interest were separated from the polymer, they were still covered by an intense band from process oil. Hence, coupled-column chromatography with reversed-phase separation of SEC eluates became neccessary. 10 pi of the latter were injected into a C 8 column (250 x 2.2 mm dP = 10 pm) and analyzed at 0.5 ml/min flow rate through a water/acetonitrile gradient (rising from 20% B by 6%/ml). Here, UV detection was performed at 254 nm. The peaks of the additives could be clearly separated from the process oil band. The technique also proved useful for checking... 

Direct analysis of the enantiomers in biological fluids is very important because it reduces both analysis time and sample preparation time. Indeed, when there is risk of the quick racemization of the enantiomer, direct analysis is essential. It has been observed that CD-based CSPs employ mobile phases that are generally compatible with biological samples, hence can be used for the direct analysis of the enantiomers in biological fluids [67,80]. Stalcup et al. [58] employed coupled column chromatography to isolate scopolamine from a plant extract and found that the extent of racemization depends on the isolation... 

Multidimensional (or coupled) column chromatography is a technique in which fractions from a separation system are selectively transferred to one or more secondary separating systems to increase resolution and sensitivity, and/or to reduce analysis time. The application of secondary columns is illustrated schematically in Figure 8.1. The smaller the AtT value applied, then the greater is the resolution and number of runs needed to check a certain portion of the sample (5). 

B.-M. Eriksson, B.-A. Persson and M. Wikstrom, Determination of urinary vanillyl-mandelic acid by direct injection and coupled-column chromatography with electrochemical detection , J. Chromatogr. 527 11-19 (1990). 

Multidimensional chromatography has been called column switching, coupled-column chromatography, recycle chromatography, and mode sequencing, among other terms. 

In coupled-column chromatography, two analytical columns are applied. A peak of interest is heartcut from the first dimension of LC and transferred to the second dimension of LC, often via a trapping column enabling intermediate concentration and mobile-phase switching. The power of coupled-column LC in significantly enhancing the selectivity of the LC separation and the reduction of interferences was demonstrated by Edlund et al. [17] already in 1989 for the analysis of... 

TSP LC-MS in combination with coupled-column chromatography was used to separate and determine drag enantiomers of terbutaline (225 Da) in human plasma [76]. The (-)terbutaline enantiomer is pharmacologically active. The method was developed for single-dose pharmacokinetic studies to determine the plasma... 

Boos, K.-S. Rudolphi, A. Vielhauer, S. Walfort, A. Lubda, D. Eisenbeiss, F. Alkyl-Diol Silica (ADS) Restricted Access Precolumn Packings for Direct Injection and Coupled-Column Chromatography of Biofiuids, Fresenius J. Anal. Chem. 352, 684-690 (1995). 

A number of alternative techniques have been developed to tackle the general elution problem, such as flow and temperature programming, and especially column switching techniques. Coupled column chromatography involves the use of three and sometimes four different stationary phases. The sample is introduced to the primary column for a preliminary separation and then the various polar fractions are switched to the appropriate secondary columns and then to the detector. Coupled column chromatography provides enhanced resolution, and as isocratic elution is used the technique is particularly useful for the routine assay of samples with a wide range of capacity factor values. Further details on these various techniques may be found in a review by Koenigbauer and Majors [96]. 

D. Haupt, Separation of (R)- and (S)-Naproxen using micellular chromatography and a,-acid glycoprotein column application to chiral monitoring in human liver microsomes by coupled column chromatography. J. Biochem. Biophys., Methods, 24 4(1992)273. 

Determination of the Enantiomeric Purity of Scopolamine Isolated From Plant Extract Using Achiral/Chiral Coupled Column Chromatography, Biomed. Chromatogr., 5(1991)3. 

Two-Dimensional Planar Chromatography and Coupled-Column Chromatography... 

M. Josefsson and B. Norlander, Coupled-column chromatography on a Chiral-AGP phase for determination of amlodipine enantiomers in human plasma An HPLC assay with electrochemical detection, J. Pharm. Biomed. Anal, 1996, 15, 267-277. 

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