Naphthalene solute retention

FIGURE 2.19 Influence of temperature on solute retention. Column ProntoSIL C18ACE, 125x4mm. Mobile phase MeOH/20mM phosphate buffer pH=7, 65/35 v/v. Samples 1, Uracil 2, propranolol 3, butylpa-raben 4, dipropylphthalate 5, naphthalene 6, acenaphthene 7, amitriptyline. 

Solute retention as a function of pressure has been determined experimentally for a wide number of solutes over a range of temperatures and pressures.(1,23-25) The tcend in retention of a solute with pressure can be predicted within the limitations of our assumptions using eq. 11. The calculations are then compared with experimental data for the retention of naphthalene and biphenyl at various temperatures and pressures were obtained with supercritical CC. ... 

Figure 4.8 illustrates both effects for a capillary column test mixture. At 90°C, dodecane is eluted last at around 11 min. As the temperature increases in 10° increments, all of the peaks retention times decrease, and the entire separation takes only 3.6 min at 120°C. The solutes retention times decrease by about half for every 15-20°C increase in colmnn temperature. However, the last two peaks merge at 100-110°C, and naphthalene becomes the last peak at 120°C. Thus, careful attention must be paid to unambiguous peak identification during a separation optimization that includes the column temperature. 

To demonstrate the effect in more detail a series of experiments was carried out similar to that of volume overload, but in this case, the sample mass was increased in small increments. The retention distance of the front and the back of each peak was measured at the nominal points of inflection (0.6065 of the peak height) and the curves relating the retention data produced to the mass of sample added are shown in Figure 7. In Figure 7 the change in retention time with sample load is more obvious the maximum effect was to reduce the retention time of anthracene and the minimum effect was to the overloaded solute itself, benzene. Despite the reduction in retention time, the band width of anthracene is still little effected by the overloaded benzene. There is, however, a significant increase in the width of the naphthalene peak which... 

The effect of temperature on retention time was investigated by Scott and Reese (3), who measured the retention volume of the solutes o-dinitro-benzene, 2-ethoxy naphthalene and p-chlorophenatole over a range of temperatures. The chromatographic conditions used are as follows,... 

The progress of this reaction may be followed by quenching aliquots of the reaction solution in acidic aqueous ammonium sulfate followed by extraction with ether and analysis of the ethereal extract by gas chromatography. With 1.2-m. gas chromatography column packed with silicone fluid. No. 710, on Chromosorb P and heated to 215°, the retention times of naphthalene and 1-bromonaphthalene were 1.9 minutes and 6.7 minutes, respectively. The submitters employed a 30-cm. gas chromatography column packed with Porpak P for this analysis. 

Figure 3.14 Variation of retention with the binary mobile phase composition for methanol-water mixtures on an ODS column. Solutes naphthalene ( ), anisole (o) and phenol (x). Thin lines eqn. (3.38) for k< 50 thick lines eqn.(3.45) for 1 < fc<10. The diverging straight lines suggest an increase of the slope parameter S (eqn.3.45) with increasing capacity factors Figure taken from ref. [322]. Reprinted with permission.

Figure 3.33 Retention (In ft) as a function of (a) pressure, (b) mobile phase density and (c) the logarithm of the mobile phase density in SFC at three different temperatures. Mobile phase carbon dioxide. Stationary phase ODS. Solute naphthalene. Figure taken from ref. [390]. Reprinted with permission. Experimental data from ref. [391].

Only one research group has illustrated the reversed phase retention behavior of solutes on zirconia-silica modified surfaces. In the study by Melo et al. on PMOS gamma-irradiated modified surfaces, the reversed phase retention behavior of a test mixture containing acetone, benzonitrile, benzene, toluene, and naphthalene was evaluated. The authors illustrated good resolution of the five-component text mixture as shown in Fig. 7. Retention, however, decreased after the stationary phase was washed with 5000 column volumes of base (pH 10). Despite the base washing, uniform peak shape was maintained, with only a slight reduction in resolution as discussed in Alkaline Stability above. 

Homogeneous-solution alkali naphthalenes (MNaph) reductions of 1-halo-1-methyl-2.2-diphc-nylcyclopropanes in aprotic solvents occur with retention of conliguration up to 51V< (Table 7.6) [96.110.152], l-Bromo- and l-chloro-I-methyl-2.2-biphenylenecyclopropanes behave similarly 196,1 I0. ... 

Known solid solution forming systems include naphthalene-theonaphthalene thiophene-benzene hexadecane-octadecane and m-chloronitrobenzene-w-fluoronitrobenzene. Further advantages of melt crystallization are the smaller volume of the liquid phase compared to the vapor phase of a substance. A smaller volume leads towards less space or less construction work, which means less capital costs. These advantages are sometimes lost if the process of crystallization and remelting is very slow therefore, the retention time in the apparatus is high. 

Figure 4.10. Plot of the retention factor as a function of the volume fraction (% v/v) of organic solvent in reversed-phase chromatography. Stationary phase is an octadecylsiloxane-bonded silica sorbent with methanol-water as the mobile phase. Solute identification 1 = naphthalene 2 = bromobenzene 3 = acetophenone 4 = 2-phenylethanol and 5 = benzamide.

The relative response of an analyte is influenced by two factors (equations 10 and 11) the relative retention of the solute (aj and the fractional coverage of the adsorbent exerted by the probe (0 ). A system with naphthalene-2-sulfonate as the probe is shown in Figure 10, where the dotted lines give the estimated relative response for cationic and anionic solutes [19, 57]. There is an increase from zero to a maximum value in the range 0-1, and the relative response then decreases and approaches an almost constant level. In order to achieve high detection sensitivity, optimization of the retention is more important than a high absorptivity of the probe. 

Only one research group has illustrated the RP retention behavior of solutes on zirconia-silica modified surfaces. In the study by Melo et al. on PMOS gamma-irradiated modified surfaces, the RP retention behavior of a test mixture containing acetone, benzonitrile, benzene, toluene, and naphthalene was evaluated. The authors... 

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