Chromatographic behavior

The first observation of the enantioselective properties of an albumin was made in 1958 (28) when it was discovered that the affinity for L-tryptophan exceeded that of the D-enantiomer by a factor of approximately 100. This led to more studies in 1973 of the separation of DL-tryptophan [54-12-6] C22H22N2O2, on BSA immobilized to Sepharose (29). After extensive investigation of the chromatographic behavior of numerous racemic compounds under different mobile-phase conditions, a BSA-SILICA hplc column (Resolvosil-R-BSA, Macherey-Nagel GmvH, Duren, Germany) was... 

Method of Moments The first step in the analysis of chromatographic systems is often a characterization of the column response to sm l pulse injections of a solute under trace conditions in the Henry s law limit. For such conditions, the statistical moments of the response peak are used to characterize the chromatographic behavior. Such an approach is generally preferable to other descriptions of peak properties which are specific to Gaussian behavior, since the statisfical moments are directly correlated to eqmlibrium and dispersion parameters. Useful references are Schneider and Smith [AJChP J., 14, 762 (1968)], Suzuki and Smith [Chem. Eng. ScL, 26, 221 (1971)], and Carbonell et al. [Chem. Eng. Sci., 9, 115 (1975) 16, 221 (1978)]. 

A precise mastery of the chromatographic process also requires that the relative humidity be controlled. There are sufficient examples demonstrating that reproducible development is only possible if temperature and relative humidity are maintained constant. The influence of the latter on chromatographic behavior can be investigated using the Vario KS chamber (Fig. 59). When the relative humidity IS altered it is possible that not only the zone behavior will be changed but also the order of the zones on the chromatogram (Fig. 60). 

Although the mechanism of SEC is in principle nonadsorptive, effects derived from different matrices can be observed. As a result, quite different chromatographic behaviors of one particular protein can be obtained depending on the type of sorbent used. 

Macaudiere and co-workers performed a comparison of LC and SFC on a polymer based-CSP (Chiralpak OT) [64]. The chromatographic behavior of this CSP seemed to be quite different in SFC than in LC, although satisfactory separations were achieved with both techniques. The chiral recognition mechanisms may be altered by the nature (hexane-based or CO,-based) of the eluent. 

Derivitization Chemical reaction of a sample that yields a product that is more volatile and stable and that has improved gas chromatographic behavior over the original substance. See Appendix 3 for derivatives found useful in GC/MS. 

The effects of various pore-size distributions, including Gaussian, rectangular distributions, and continuous power-law, coupled with an assumption of cylindrical pores and mass transfer resistance on chromatographic behavior, have been developed by Goto and McCoy [139]. This study utilized the method of moments to determine the effects of the various distributions on mean retention and band spreading in size exclusion chromatography. 

Because trls has only meager buffering action at pH 6.1, fluctuations In the pH of Ion exchanger and solutions may occur and may result In abnormal chromatographic behavior. Buffered conditions may be obtained by substituting bls-trls which has a pK of about 6.5, and virtually Identical behavior results If Developer A Is constituted with 0.03 M bls-trls-HCl 0.03 M NaCl 0.01% KCN at pH 6.2. 

The development and reports of methods for colorless chlorophyll derivative (RCCs, FCCs, and NCCs) analysis are relatively recent and the structures of the compounds are being elucidated by deduction from their chromatographic behaviors, spectral characteristics (UV-Vis absorbance spectra), mass spectrometry, and nuclear magnetic resonance analysis. The main obstacle is that these compounds do not accumulate in appreciable quantities in situ and, moreover, there are no standards for them. The determination of the enzymatic activities of red chlorophyll catabolite reductase (RCCR) and pheophorbide a monoxygenase (PAO) also helps to monitor the appearance of colorless derivatives since they are the key enzymes responsible for the loss of green color. ... 

The identification of a known carotenoid should be based, at least, on the information obtained from the following criteria chromatographic behavior in two... 

The mobile phase should not produce chemical transformations of the separated components because it can modify the chromatographic behavior of the system. Solvents having weak reversible bonds with the solute are recommended. 

This consists in spotting the separation mixture at intervals on a chromatographic plate and then applying the selected solvents in the center of each spot by means of a thin capillary. The spots migrate radially, and different chromatographic behavior of spotted rnixmre can be observed [16,59]. 

A review on TLC and PLC of amino adds, peptides, and proteins is presented in the works by Bhushan [24,25]. Chromatographic behavior of 24 amino acids on silica gel layers impregnated tiraryl phosphate and tri-n-butylamine in a two-component mobile phase (propanol water) of varying ratios has been studied by Sharma and coworkers [26], The effect of impregnation, mobile phase composition, and the effect of solubility on hRf of amino acids were discussed. The mechanism of migration was explained in terms of adsorption on impregnated silica gel G and the polarity of the mobile phase used. 

The different organic modifiers used to derive the most suitable mobile phases lead to different parameters namely isocratic logfe and extrapolated logkw. The extrapolation method has no reality in terms of chromatographic behavior of solutes. However, mainly by correlation with log Pod (Eqs. 2 and 3) several studies have demonstrated the interest of these extrapolated retention factors as predictors of the lipophilicity of solutes. 

R. M. Lopes Marques, P.J. Schoenmakers, C.B. Lucasius and L.M.C. Buydens, Modelling chromatographic behavior as a function of pH and solvent composition in RPLC. Chromatographia, 36 (1993) 83-95. 

Huisman, T. H. J. and Dozy, A. M., Studies on the heterogeneity of hemoglobin. IV. Chromatographic behavior of different human hemoglobins on anion-exchange cellulose (DEAE-cellulose), /. Chromatogr., 7, 180, 1962. 

Roush, D. J., Gill, D. S., and Willson, R. C., Anion-exchange chromatographic behavior of recombinant rat cytochrome b5. Thermodynamic driving forces and temperature dependence of the stoichiometric displacement parameter Z, /. Chromatogr., 653, 207, 1993. 

Herman, D. P, Field, L. R., and Abbott, S., The size-exclusion chromatographic behavior of synthetic water-soluble polymers on diol bonded phase supports, /. Chromatogr. Sci., 19, 470, 1981. 

Lu, X. M., Benedek, K., and Karger, B. L., Conformational effects in the high-performance liquid chromatography of proteins. Further studies of the re-versed-phase chromatographic behavior of ribonuclease, ]. Chromatogr., 359, 19, 1986. 

Based on the data from animal studies, diisopropyl methylphosphonate is principally excreted in the urine as the metabolite IMPA (Hart 1976 Ivie 1980). Chromatographic behavior of urinary metabolites does not change after the urine is treated with glucuronidase and sulfatase, so there is no conjugation of diisopropyl methylphosphonate or IMPA by microsomal enzymes (Hart 1976). There was minimal excretion of diisopropyl methylphosphonate metabolites in bile (Hart 1976) or in the milk of a lactating cow (<1%) (Palmer et al. 1979). 

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