Column Selection Guides

Column selection during method development often reflects personal preferences or prior experience.1,4,6 Nevertheless, some general guidelines can be suggested based on consensus of experienced chromatographers. Note that these recommendations focus on RPLC. 

Manufacturer Sorbent Surface Area (m2/g) Pore Size A Notes 

This chapter provides an overview of essential column concepts, including a general description, types, packing, modern trends, and selection guide. While 

HPLC Columns Theory, Technology, and Practice, Wiley-VCH, New York, 1997. 

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TABLE 4.11 Recommended Column Selection Guide for High-Performance Gel-Filtration Chromatography... 

Table 9.1.1. Column selection guide for stationary phases used in capillary columns...

While samples such as these have obviously been the focus for much GC X GC work in the past, the technology still remains to be demonstrated for many other sample types. It is likely that in the near future, as many more applications are studied, a general theory-or at least a guide to column selection for GC X GC applications-will reveal a logical approach to selection of phases that embodies the principles of orthogonality of separation. 

Column selection remains the most important factor in successful enantiomeric separations. The CSPs most likely to be effective in SFC are those that have been employed under normal phase conditions in LC. In fact, the tremendous body of knowledge that has been accumulated for LC can also guide column selection in SFC [66]. The likelihood of success with a particular CSP can generally be gauged after one or two injections [67]. If no evidence of separation is observed, another CSP should be investigated. 

Trying to determine which column is ideal for a specific analysis can be difficult with over 1000 different columns on the market [74]. A proper choice implies a definition of parameters such as column material, stationary phase (polarity), i.d., film thickness and column length. Guides to column selection are available [74,75]. The most important consideration is the stationary phase. When selecting an i.d., sample concentration and instrumentation must be considered. If the concentration of the sample exceeds the column s capacity, then loss of resolution, poor reproducibility and peak distortion will result. Film thickness has a direct effect on retention and the elution temperature for each sample compound. Longer columns provide more resolving probe, increase analysis times and cost. 

Many excellent reviews on the development, instrumentation and applications of LC-MS can be found in the literature [560-563]. Niessen [440] has recently reviewed interface technology and application of mass analysers in LC-MS. Column selection and operating conditions for LC-MS have been reviewed [564]. A guide to LC-MS has recently appeared [565]. Voress [535] has described electrospray instrumentation, Niessen [562] reviewed API, and others [566,567] have reviewed LC-PB-MS. For thermospray ionisation in MS, see refs [568,569]. Nielen and Buytenhuys [570] have discussed the potentials of LC-ESI-ToFMS and LC-MALDI-ToFMS. Miniaturisation (reduction of column i.d.) in LC-MS was recently critically evaluated [571]. LC-MS/MS was also reviewed [572]. Various books on LC-MS have appeared [164,433,434,573-575], some dealing specifically with selected ionisation modes, such as CF-FAB-MS [576] or API-MS [577],... 

P. Sandra, G. Vanhoenacker, F. Lynen, L. Li and M. Schelfaut, Consideration on column selection and operating conditions for LC/MS, Guide to LC/MS, LCGC Europe, Advanstar Communications, Chester UK, 8-21, December 2001. 

Application Guide for Chiral Column Selection Crownpak-Chiralcel-Chiralpak. Chiral HPLC Column for Optical Resolution. 2nd Ed.. Daicel Chemical Industries. Ltd.. Tokyo. 

Application Guide for Chiral Column Selection, Second Edition, Chiral Technologies Inc., Exton PA, 1995, p. 39... 

Notable attempts have been made toward a systematic classification of stationary phases in GC. The column classification system conceived by Rohrschneider [80], and further developed by McReynolds [81], does provide a valuable guide in the column selection process. Most commercial phases have now been characterized. More quantitative and elaborate approaches toward the characterization of liquid phases in GC involve solubility parameters and other thermodynamic considerations... 

Figure 6.47 Simplified guide to column selection (a) for organic-soluble samples (b) for water-soluble samples.

Afloqualone enantiomers were resolved on CSP composed of an immobilized (+)-18-crown-6 tetracarboxyhc add on 3-aminopropylsila-nized silica-gel (98JC(A805)85) and on a Chiralpak AS column (see chromatograms in Application Guide for Chiral Column Selection, Daicel Internet Home Page http //www.daicel.co.jp/chiral/)... 

A Selection Guide to DEXTM Columns Stable derivatized cyclodextrin stationary phases for high resolution analyses of optical and positional isomers. In Chiral Cyclodextrin Capillary GC Columns. Sigma-Aldrich Co. Available at http // vww.sigmaaldrich.eom/etc/medialib/docs/Supelco/Bulletin/6504.Par.0001.File.tmp/ 6504.pdf. 

The aforementioned discussion was general in nature and also included conventional contactors such as tray and packed columns. In the case of three-phase (G-L-S) reactions, such conventional contactors are not used. The stirred reactor is the workhorse of the fine chemicals industry. The gas-inducing reactor can be considered as an alternative to stirred reactors when a pure gas is used. However, this reactor has several drawbacks (Chapter 9). In view of this, the venturi loop reactor has been widely used as a safe and energy-efficient alternative to the conventional stirred reactor. Table 3.3 summarizes the preceding discussion in the form of a multiphase reactor selection guide. 

Guides to column and stationary phase selection Guides to column installation Guides to derivatization Troubleshooting guides... 

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