Retention data for

Appllca.tlons. The first widely appHcable Ic separation of enantiomeric metallocene compounds was demonstrated on P-CD bonded-phase columns. Thirteen enantiomeric derivatives of ferrocene, mthenocene, and osmocene were resolved (7). Retention data for several of these compounds are listed in Table 2, and Figure 2a shows the Ic separation of three metallocene enantiomeric pairs. P-Cyclodextrin bonded phases were used to resolve several racemic and diastereomeric 2,2-binaphthyldiyl crown ethers (9). These compounds do not contain a chiral carbon but stiU exist as enantiomers because of the staggered position of adjacent naphthyl rings, and a high degree of chiral recognition was attained for most of these compounds (9). 

Table 2. Retention Data for Racemic Compounds Separated on a p-Cyclodextrin Stationary Phase ...

Retention data for the -chloroalkanes was available over a limited temperature range of 76°C to 88°C on a n-C30 alkane stationary phase. The same procedure is used values for Log(V r(T)) for the solutes n-chlorobutane, n-chloropentane, n-... 

The column was 25 cm long, 4.6 mm I.D. and packed with Partisil 10. It is seen that linear curves were obtained for three different solutes and two different moderators in n-heptane. Scott and Beesley [14] obtained retention data for the two enantiomers, (S) and (R) 4-benzyl-2-oxazolidinone. The column chosen was 25 cm long, 4.6 mm I.D. packed with 5 mm silica particles bonded with the stationary phase Vancomycin (Chirobiotic V provided by Advanced Separations Technology Inc., Whippany, New Jersey). This stationary phase is a macrocyclic glycopeptide Vancomycin that has a molecular weight of 1449.22, and an elemental composition of 54.69% carbon. 

Prinsloo SM, De Beer P143R. 1985. Gas chromatographic relative retention data for pesticides on nine packed columns I. Organophosphorus pesticides, using flame photometric detection. J Assoc Off Anal Chem 68 1100-1108. 

Also, since it relies on acciirate retention data for each solute in all chrosatograBs, peak labelling is required. 

Hafkenscheid, T.L., Tomlinson, E. (1983a) Isocratic chromatographic retention data for estimating aqueous solubilities of acidic, basic and neutral drugs. Inti. J. Pharm. 16, 1-21. 

Opperhuizen, A., Sinnige, T.L., van der Steen, J.M.D., Hutzinger O. (1987) Differences between retentions of various classes of aromatic hydrocarbons in reversed-phase high-performance liquid chromatography. Implications of using retention data for characterizing hydrophobicity. J. Chromatogr. 388, 51-64. 

Quinones and Hydroqulnones. In the analysis of quin-ones and hydroqulnones, the use of two different dual detector systems was required. The retention data for hydroqulnones shows the normal behavior of hydroxyl groups associating with the solvent, THF. Thus octyl quinone and hydroquinone elute almost together. Similarly dioctylquinone and octyl hydroquinone elute together (Figure 7). The UV/RI response ratio for benzoquinone is 3.75. Hydroquinone and dioctylquinone show similar disparities in the UV/RI responses. This information provides a very good method for detecting impurities in dioctyl hydroquinone. 

Possible difficulties in obtaining accurate retention data for physicochemical measurements should be recognized, however. The evaluation of to, the elution time of an "unretained peak (274) is often connected with systematic error and the measurement of the retention time of asymmetrical peaks may not be accurate. Moreover, no satisfactory methods are available for the precise evaluation of the phase ratio in the column. Consequently, the measurement of the equflibrium constant proper is beset with difficulties as discussed in Section VII.B. 

Cluster analysis (numerical toxonomic aggregation) is applied to arrange phases according to their chromatographic behaviour. A set of retention data for 16 monofimctional benzenes, 110 difunctional benzenes and 15 trifunctional benzenes was subjected to analysis. Three groups of stationary phases can be distinguished polar, non-polar, and polyfluorinated. A linear relationship between the retention data of two stationary phases of the same class can be worked out. This linear relationship fits the model... 

The mass chromatographic technique obviously has a wide scope of applications in the identification of volatile compounds. Its main limitation is the lack of retention data for all possible compounds. This is not... 

Hafkenscheid, T.L. and E. Tomlinson. 1983. Isocratic Chromatographic Retention Data for Estimating Aqueous Solubilities of Acid in Basic and Neutral Drugs. Int. J. Pharm. 16, 1-20. 

Table 13.7 Comparison of retention data for an environmental sample using different ultrafiltration methods...

Table 13.8 Comparison of laboratory and environmental ultrafiltration retention data for 137Cs...

Solute retention as a function of temperature at constant pressure is seen to be dependent on the partial molar enthalpy of solute transfer between the mobile and stationary phases, the neat capacity of the supercritical fluid mobile phase and the volume expansivity of the fluid. The model was compared to chromatographic retention data for solutes in n-pentane and CO2 as the fluid mobile phase and was seen to fit the data well. 

There are several compilations of chromatographic data that may be of use in setting up a method of analysis. The ASTM has published retention data for GC,6 LC,7 and SEC.8... 

McReynolds9 has published GC retention data for 400 compounds on 77 stationary phases at two temperatures. These data are of particular value because they were obtained under the same conditions by the same person and are therefore self-consistent. For TLC data, see the references provided at the end of Chapter 10. 

Other workers [35] have described several methods for the silylation of different stereoisomers of menthol and separated them on a column coated with SE-30. They recommend n-butyl boronates for the GC analysis of menthoglycol and neomentho-glycol and HFB esters for sensitive analysis at the nanogram level. Retention data for some derivatives of these substances are listed in Table 5.3. 

The experimental results with T-CD indicate (Table II) that the retention of substances examinated is not perceptibly affected by inclusion due to the large cavity of the cyclodextrin (14) Therefore, the retention data for all the p-isomers of dialkylbenzenes are lowest in contrast to the highest values for these derivatives on P-CD Among the disubstituted alkylbenzenes the o-isomers are retained most, owing to their more voluminous special... 

Table 12. Retention data for some volatile hypnotic Cctrbcwax System GA...

Reference Solution. Prepare an aqueous solution containing 0,2 mg/ml of each of ethanol, methanol, isopropyl alcohol, and propMiol, and inject 1 jiil on to the column. The retention data for these compounds are listed in Table 14,... 

OV-17 is phenylmethyl silicone, a useful, moderately polar, silicone phase with a high maximum operating temperature (350°). It is more oxygen-sensitive than most silicone phases and is available in capillary columns. A considerable amount of retention data for drugs on this phase has been published. 

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