Chromatographic classification

Euerby, M. R. and Petersson, P., Chromatographic Classification and Comparison of Commercially Available Reversed-phase Liquid Chromatographic Columns Using Principal Component Analysis, /. Chromatogr. A, 994 13—36, 2003. 

M. Euerby, A. McKeown, and R Petersson, Chromatographic classification and comparison of commercially available perfluorinated stationary phases for reversed-phase liquid chromatography using principal component analysis,/. Sep. 

Peracid Classification. Peracids can be broadly classified into organic and inorganic peracids, based on standard nomenclature. The limited number of inorganic peracids has required no subclassification scheme (4). However, the tremendous number of new organic peracids developed (85) has resulted in proposals for classification. Eor example, a classification scheme based on Hquid chromatography retention times and critical miceUization constants (CMC) of the parent acids has been proposed (89). The parent acids are used because of the instabiHty of the peracids under chromatographic and miceUization measurement conditions. This classification scheme is shown in Table 1. 

Fig. 1. Classification of chromatographic systems where gsc is gas—soHd chromatography glc, gas—Hquid chromatography sec, size-exclusion chromatography Isc, Hquid—soHd chromatography Uc, Hquid—Hquid chromatography iec, ion-exchange chromatography tic, thin-layer chromatography ...

Each of the PLgel individual pore sizes is produced hy suspension polymerization, which yields a fairly diverse range of particle sizes. For optimum performance in a chromatographic column the particle size distribution of the beads should be narrow this is achieved by air classification after the cross-linked beads have been washed and dried thoroughly. Similarly, for consistent column performance, the particle size distribution is critical and is another quality control aspect where both the median particle size and the width of the distribution are specified. The efficiency of the packed column is extremely sensitive to the median particle size, as predicted by the van Deemter equation (4), whereas the width of the particle size distribution can affect column operating pressure and packed bed stability. 

Saturated solutions of some reagents (T) 829 Schoniger oxygen flask see Oxygen flask Schwarzenbach classification 53 Screened indicators 268 Sebacic acid 469 Secondary pH standards 831 Selective ion meters 567 Selectivity coefficient, 559 in EDTA titrations, 312 in fluorimetry, 733 of analytical methods, 12 Selenium, D. of as element, (g) 465 Semi-log graph paper 572 Sensitivity (fl) 834, (fu) 732 Separation coefficient 163, 196 Separations by chromatographic methods, 13, 208. 233, 249... 

Seleetion of basic parameters of chromatographic process (stationary phase, proper pure solvents according to Snyder s classification, and vapor phase)... 

Snyder s classification of solvent properties is important in the selection of the chromatographic conditions and the optimization of the chromatographic processes. 

The solvent triangle classification method of Snyder Is the most cosDBon approach to solvent characterization used by chromatographers (510,517). The solvent polarity index, P, and solvent selectivity factors, X), which characterize the relative importemce of orientation and proton donor/acceptor interactions to the total polarity, were based on Rohrscbneider s compilation of experimental gas-liquid distribution constants for a number of test solutes in 75 common, volatile solvents. Snyder chose the solutes nitromethane, ethanol and dloxane as probes for a solvent s capacity for orientation, proton acceptor and proton donor capacity, respectively. The influence of solute molecular size, solute/solvent dispersion interactions, and solute/solvent induction interactions as a result of solvent polarizability were subtracted from the experimental distribution constants first multiplying the experimental distribution constant by the solvent molar volume and thm referencing this quantity to the value calculated for a hypothetical n-alkane with a molar volume identical to the test solute. Each value was then corrected empirically to give a value of zero for the polar distribution constant of the test solutes for saturated hydrocarbon solvents. These residual, values were supposed to arise from inductive and... 

The first classification is based on the nature of the detector response. Table 4.7 ranks several chromatographic detectors as specific and nonspecific. A nonspecific or universal detector responds to all solutes present in the mobile phase and this performance makes it a... 

Figure 4.10 Classification of liquid chromatographic methods depending on the polarity of the stationary and mobile phases. After Schaffer el at. [537]. Reproduced by permission of Metrohm AG, Herisau, Switzerland...

E Ruckenstein, V Lesins. Classification of liquid chromatographic methods based on the interaction forces The niche of potential barrier chromatography. In A Mizrahi, ed. Advances in Biotechnological Processes, Vol 8 Downstream Processes Equipment and Techniques. New York Alan R. Liss, 1988, pp 241-314. 

Mottran, H. R., S. N. Dudd, G. J. Lawrence, A. W. Stott, and R. P. Evershed (1999), New chromatographic, mass spectrometric and stable isotope approaches to the classification of degraded animal fats preserved in archaeological pottery,. Chro-matogr. A 833, 209-221. 

The three major classifications, with instrument names in parentheses, are spectroscopy (spectrometer), chromatography (chromatograph), and electroanalytical chemistry (no specific name). 

A. Cichelli and G.P. Pertesana, High-performance liquid chromatographic analysis of chlorophylls, pheophytins and carotenoids in virgin olive oils chemometric approach to variety classification. J. Chromatogr.A 1046 (2004) 141-146. 

Differential scanning calorimetry (DSC) is a common technique for the classification of individual phase transitions in liquid-crystalline materials and has been applied for the phase characterization of alkyl-modified chromatographic surfaces. Hansen and Callis [187] applied DSC to investigate phase changes in Cig and C22... 

In this section a variety of analytical separations reported in the literature are reviewed to show the wide structural diversity of eluite which can be separated by RPC and to assist the reader in becoming similar with the use of this fluid chromatographic technique. The descriptions are ar-ranged according to the matrix in which an analyte is found or the area of - h istry in which the samples are generally encountered. Thus theophylline, for example, is regarded as a nucleotide and, for the most part, its analysis in food samples is found with appropriate cross references. On the other hand, the separations of pharmaceuticals found in serum, urine, and pharmaceutical samples are cited separately. It is hoped that this method of classification may serve the purposes of those wh e analytical interests are incidental to their primary research pursuits. 

Basis of Classification of Chromatographic Methods Classification is based on the phenomenon involving the process of either partition or adsorption. 

L.R. Snyder, Classification of the solvent properties of common liquids. Journal of Chromatographic Science, 16 (1978) 223-234. 

---